Want to see the details?CLICK HERE to view full-screen photo.
Check out those five targets. The Aggregate (average) of all five targets is a tiny 0.0840 inches! These were shot by Gary Ocock at 100 yards in a California benchrest match on August 6, 2017. Though Gary’s 0.0840 Agg beats existing records, this was not a “sanctioned” match, so Gary’s killer Agg was NOT submitted for IBS or NBRSA records. So, sadly, the Agg won’t appear in the record books, but this remains a spectacular, verified feat of rifle accuracy, accomplished in competition.
Gary’s red railgun is arguably the Most Accurate Gun Ever Built. As far as we can determine, no one has ever shot a smaller 5-target Agg anywhere, at any time. FYI, the NBRSA Unlimited Class 5×5 Aggregate World Record is 0.1242″ shot by Jerry Lahr in 2012. Gary’s 0.0840″ Agg is much smaller.
The Unlimited Benchrest Record That Will Never Be (Official)
Report by Boyd Allen
Gary Ocock’s stunning unlimited Aggregate is beyond amazing. That’s an average of five, 5-shot groups of .0840. Shot under sanctioned match rules, but at an unsanctioned 100-yard fun match, this Aggregate is well under the current 100-yard official records of the IBS (.1386), and the NBRSA (.1242). The fourth of the five groups measured a minuscule .018, less than half the size of the existing NBRSA Unlimited record of .049 (also shot by Gary). Check it out:
When the top 15 shooters all post teen Aggs, conditions must be pretty favorable. However there were some light switchy winds — Gary said that he shot better in the left to right condition.
GUN SPECIFICATIONS
Ocock’s red Jay Young Unlimited Railgun features one major difference from Young’s typical Railgun designs. The bottom of the barrel block is integral with the top (moving part), of the gun. The barrel is Ocock’s usual 1:13.5″-twist Krieger chambered for the 6 PPC. The BAT Neuvo action* is unusual in that its lugs are horizontal at lock-up instead of the usual vertical. With horizontal lugs, both lugs maintain contact with their abutments when the action is cocked. In the more normal configuration when cocked the top lug is forced off of its seat by a combination of the angle of the trigger cocking piece interface, the pressure of the striker spring, and bolt clearance at the rear of the action.
LOAD SPECIFICATIONS
Gary shot this remarkable Agg with well-used brass, Vihtavuori N133 powder, and self-made 66gr BT bullets** seated at “jam”. This amazing Agg was shot on the second day of a 2-day Unlimited Benchrest match. On Day 1 Gary had experimented with various loads using both surplus IMR 8208 and Vihtavuori N133, but was not satisfied with the results. For his first group on Day 2, Gary tried a light load of N133. After seeing the result, however, he decided to go to the other extreme — a super stout N133 load — with the same powder. As you can see, Gary’s willingness to experiment paid off.
Notably, Gary used light neck tension. Ocock found that for these bullets and this barrel, light neck tension worked best (contrary to “normal” N133 benchrest practice). Ocock used a bushing that only produces .001″ difference between the diameters of sized and loaded case necks.
This video shows a line-up of Rail-Guns. One of Gary Ocock’s Rails appears at the 0:35 time-mark.
Comment on Ocock’s Achievement
Congratulations to Gary Ocock for superb shooting (and smart loading). Even though the match was not sanctioned (so the Agg will never be a record), Ocock has raised the bar very high, and given us a new standard of ultimate accuracy.
Though this 0.0840 Aggregate and 0.018 group will never go into the record group, they are still noteworthy. There’s virtually no doubt that they would have survived inspection by any record committee. Except for the lack of fixed backers, an IBS requirement (for detecting cross-fires), all other conditions were met for an officially-sanctioned match.
Ocock Did Set Single-Group IBS World Record with Red Railgun
Photo credit: Ben Zentner
Here is Gary with his Red Railgun at a Visalia event in October 2017. Ocock let the event’s youngest competitor, 12-year-old Gavin Lichtenwalter, shoot Gary’s new Railgun for the last three matches on Sunday afternoon. The day before, 10/21/17, Gary shot an IBS Heavy Benchrest World Record putting five shots in just 0.045 inches, as certified by the IBS record committee. Here is that group, as first measured at the range at 0.039 inches. Gary also holds the Unlimited 5-Shot NBRSA 100-Yard Record with an 0.049 inch single group shot on 10/17/2009.
*The new BAT Neuvo actions are the result of a collaboration between Dwight Scott, and Bruce Thom, featuring Dwight’s ideas and BAT’s proven manufacturing expertise.
** Ocock shot his own, boat-tail match bullets, made with George Ulrich-crafted dies using Hood cores. Although he said that it had been a while since he had weighed any, his best guess was that they weigh something around 66.5 grains.
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Here is a simple, low-cost way to get reliable readings of case headspace when you “bump” the shoulder back on your 6BR, .243 Win, or .308 Win brass. Credit Boyd Allen for this tip. First, you’ll need one .45 ACP case (.40 SW works too), with primer removed. Make sure the pistol case is trimmed square and that it is round. We recommend you first size it, trim it and chamfer. Next, take the .45 ACP (or .40 SW) case and slip it over the neck of a fired, unsized rifle case with the primer removed. Align the two cases between the jaws of your calipers and note the length from rim to rim (See photo below, with striped case).
OK, now you have the length for a fired rifle case BEFORE sizing. Next, take a full-length sized rifle case (without primer) and do the same thing, placing the pistol case over the neck of the FL-sized case (Bottom Photo). The difference between the two numbers is the amount of “bump” or set-back you are applying to the shoulder. Here the difference is .0015″. The amount of bump you need varies with your chamber and your load, but .0015-.002″ is a good initial setting. By using this simple tool, you can avoid bumping the shoulder too much. This will also help you set-up the depth of your full-length die to get the proper amount of bump each time.
Other Pistol Brass Types Work Too: Some folks have used this method but they prefer to work with 10mm or .40 SW brass rather than a .45 ACP, because slightly smaller-diameter pistol cases may conform to the shoulders of their sized rifle cases a bit better. That works fine — use whatever pistol brass case works best for your rifle brass. We got very repeatable results with .45 ACP brass but the method also works with 10mm or .40 SW brass. Just be sure the pistol brass has been sized, trimmed, chamfered, and de-burred.
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When he measures his loads or sorts bullets by weight, Forum Member Boyd Allen often employs his trusty RCBS 10-10 balance beam scale (although he does have handy digital scales as well). He finds that the balance beam scale works predictably, time after time, and it doesn’t suffer from the drift and calibration issues that plague some of the less expensive electronic scales on the market.
To make it easier to see the balance point, Boyd has adapted a magnifying glass with a mirror. This makes the end of his balance beam easier to view from his normal position on the bench. Boyd explains: “This set-up uses a cheap magnifier with positioning arms that was probably designed to hold and magnify small objects while soldering them. I think that it came from Harbor Freight many years ago. The mirror lets you look at the scale as if is was at eye level, and of course the magnifier makes the image easier to see.”
If you have a balance beam scale, we suggest you try this simple enhancement. We predict you’ll find the magnifier speeds up the process with enhanced assurance of your load weight.
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Want to see the details?CLICK HERE to view full-screen photo.
Here are five targets, each with FIVE shots in essentially one hole. This amazing feat of accuracy was accomplished six years ago. We are reprising our report because this five-target Aggregate arguably represents the most impressive feat of 100-yard accuracy in the history of marksmanship on this planet.
Check out those five targets. The Aggregate (average) of all five targets is a tiny 0.0840 inches! These were shot by Gary Ocock at 100 yards in a California benchrest match on August 6, 2017. Though Gary’s amazing 0.0840 Five-Target Agg beats existing records, this was not a “sanctioned” match, so Gary’s killer Agg will NOT be submitted for IBS or NBRSA records. So, sadly, the Agg won’t appear in the record books, but this remains a spectacular, verified feat of rifle accuracy, accomplished in competition.
The argument can be made that this is the Most Accurate Gun Ever Built. As far as we can determine, no one has ever shot a smaller 5-target Agg anywhere, at any time.
The Unlimited Benchrest Record That Will Never Be (Official)
Report by Boyd Allen
Gary Ocock’s stunning unlimited Aggregate is beyond amazing. That’s an average of five, 5-shot groups of .0840. Shot under sanctioned match rules, but at an unsanctioned 100-yard fun match, this Aggregate is well under the current 100-yard official records of the IBS (.1386), and the NBRSA (.1242). The fourth of the five groups measured a minuscule .018, less than half the size of the existing NBRSA Unlimited record of .049 (also shot by Gary). Check it out:
When the top 15 shooters all post teen Aggs, conditions must be pretty favorable. However there were some light switchy winds — Gary said that he shot better in the left to right condition.
GUN SPECIFICATIONS
Ocock’s red Jay Young Unlimited Railgun features one major difference from Young’s typical Railgun designs. The bottom of the barrel block is integral with the top (moving part), of the gun. The barrel is Ocock’s usual 1:13.5″-twist Krieger chambered for the 6 PPC. The BAT Neuvo action is unusual in that its lugs are horizontal at lock-up instead of the usual vertical. With horizontal lugs, both lugs maintain contact with their abutments when the action is cocked. In the more normal configuration when cocked the top lug is forced off of its seat by a combination of the angle of the trigger cocking piece interface, the pressure of the striker spring, and bolt clearance at the rear of the action.
LOAD SPECIFICATIONS
Gary shot this remarkable Agg with well-used brass, Vihtavuori N133 powder, and self-made 66gr BT bullets* seated at “jam”. This amazing Agg was shot on the second day of a 2-day Unlimited Benchrest match. On Day 1 Gary had experimented with various loads using both surplus IMR 8208 and Vihtavuori N133, but was not satisfied with the results. For his first group on Day 2, Gary tried a light load of N133. After seeing the result, however, he decided to go to the other extreme — a super stout N133 load — with the same powder. As you can see, Gary’s willingness to experiment paid off.
Notably, Gary used light neck tension. Ocock found that for these bullets and this barrel, light neck tension worked best (contrary to “normal” N133 benchrest practice). Ocock used a bushing that only produces .001″ difference between the diameters of sized and loaded case necks.
Comment on Ocock’s Achievement
Congratulations to Gary Ocock for superb shooting (and smart loading). Even though the match was not sanctioned (so the Agg will never be a record), Ocock has raised the bar very high, and given us a new standard of ultimate accuracy.
Though this 0.0840 Aggregate and 0.018 group will never go into the record group, they are still noteworthy. There’s virtually no doubt that they would have survived inspection by any record committee. Except for the lack of fixed backers, an IBS requirement (for detecting cross-fires), all other conditions were met for an officially-sanctioned match.
Boyd Allen notes: The reason that the match was not sanctioned was that the sanctioning bodies like to have a month’s notice when scheduling a sanctioned match and because the range had been down for modifications and this was the first match after that, there was some question as to whether the work required to have stationary backers could be finished in time for the match. Rather than promise what might not be deliverable, the decision was made to hold the match under all of the usual competition rules as a non-sanctioned “fun” match. None of this diminishes Gary’s performance.
* Gary Ocock shot his own, boat-tail match bullets, made with George Ulrich-crafted dies using Hood cores. Although he said that it had been a while since he had weighed any, his best guess was that they weigh something around 66.5 grains.
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TEN Shots in 0.303″ (0.289 MOA) at 100 Yards
Look at that target showing TEN shots at 100 yards, with eight (8) shots in the main cluster at the top. The ten-shot group measures .303″ (0.289 MOA), as calculated with OnTarget Software. Not bad for a handgun — a very nice bolt-action XP-100 pistol! What do you think, can your best-shooting rifle match the 10-shot accuracy of this XP-100 pistol?
Report by Boyd Allen
This story goes back a few seasons… this remarkable XP-100 pistol belongs to Dan Lutke, a Bay Area benchrest shooter who publishes the results for the Visalia matches to the competitors and the NBRSA. He has been an enthusiastic competitor for an number of years, at various ranges, notably Visalia and Sacramento. The action is a Remington XP-100, to which a Kelbly 2 oz. trigger has been fitted. On top is an old Japanese-made Tasco 36X scope (these were actually pretty darn good). The Hart barrel (a cast-off from Dan’s Unlimited rail gun) was shortened and re-chambered for the 6x45mm, a wildcat made by necking-up the .223 Remington parent case. The custom stock/chassis was CNC-machined by Joe Updike from 6061 Billet Aluminum to fit the XP-100 action and mount a target-style AR grip with bottom hand rest. The gun was bedded and assembled by Mel Iwatsubu. In his XP-100 pistol, Dan shoots 65gr custom boat-tails with Benchmark powder.
This diagram shows the most common 6x45mm wildcat, which is a necked-up version of the .223 Remington parent cartridge. NOTE: The dimensions for Dan Lutke’s benchrest version of this cartridge may be slightly different.
ACAD drawing by Peter Gnanapragasam CC by SA 3.0, via Wikimedia Commons. Title Added.
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Here is a simple, low-cost way to get reliable readings of case headspace when you “bump” the shoulder back on your 6BR, .243 Win, or .308 Win brass. Credit Boyd Allen for this tip. First, you’ll need one .45 acp case (.40 SW works too), with primer removed. Make sure the pistol case is trimmed square and that it is round. We recommend you first size it, trim it and chamfer. Next, take the .45 acp (or .40 SW) case and slip it over the neck of a fired, unsized rifle case with the primer removed. Align the two cases between the jaws of your calipers and note the length from rim to rim (See photo below, with striped case).
OK, now you have the length for a fired rifle case BEFORE sizing. Next, take a full-length sized rifle case (without primer) and do the same thing, placing the pistol case over the neck of the FL-sized case (Bottom Photo). The difference between the two numbers is the amount of “bump” or set-back you are applying to the shoulder. Here the difference is .0015″. The amount of bump you need varies with your chamber and your load, but .0015-.002″ is a good initial setting. By using this simple tool, you can avoid bumping the shoulder too much. This will also help you set-up the depth of your full-length die to get the proper amount of bump each time.
Other Pistol Brass Types Work Too: Some folks have used this method but they prefer to work with 10mm or .40 SW brass rather than a .45 acp, because slightly smaller-diameter pistol cases may conform to the shoulders of their sized rifle cases a bit better. That works fine — use whatever pistol brass case works best for your rifle brass. We got very repeatable results with .45 acp brass but the method also works with 10mm or .40 SW brass. Just be sure the pistol brass has been sized, trimmed, chamfered, and de-burred.
Share the post "Cheap Tricks: Measure Shoulder Bump Using a Pistol Case"
TEN Shots in 0.303″ (0.289 MOA) at 100 Yards
Look at that target showing TEN shots at 100 yards, with eight (8) shots in the main cluster at the top. The ten-shot group measures .303″ (0.289 MOA), as calculated with OnTarget Software. Not bad for a handgun — a very nice bolt-action XP-100 pistol! What do you think, can your best-shooting rifle match the 10-shot accuracy of this XP-100 pistol?
Report by Boyd Allen
This story goes back a few seasons… this remarkable XP-100 pistol belongs to Dan Lutke, a Bay Area benchrest shooter who publishes the results for the Visalia matches to the competitors and the NBRSA. He has been an enthusiastic competitor for an number of years, at various ranges, notably Visalia and Sacramento. The action is a Remington XP-100, to which a Kelbly 2 oz. trigger has been fitted. On top is an old Japanese-made Tasco 36X scope (these were actually pretty darn good). The Hart barrel (a cast-off from Dan’s Unlimited rail gun) was shortened and re-chambered for the 6x45mm, a wildcat made by necking-up the .223 Remington parent case. The custom stock/chassis was CNC-machined by Joe Updike from 6061 Billet Aluminum to fit the XP-100 action and mount a target-style AR grip with bottom hand rest. The gun was bedded and assembled by Mel Iwatsubu. In his XP-100 pistol, Dan shoots 65gr custom boat-tails with Benchmark powder.
This diagram shows the most common 6x45mm wildcat, which is a necked-up version of the .223 Remington parent cartridge. NOTE: The dimensions for Dan Lutke’s benchrest version of this cartridge may be slightly different.
ACAD drawing by Peter Gnanapragasam CC by SA 3.0, via Wikimedia Commons. Title Added.
Story tip from Boyd Allen. We welcome reader submissions.
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Want to see the details?CLICK HERE to view full-screen photo.
Check out those five targets. The Aggregate (average) of all five targets is a tiny 0.0840 inches! These were shot by Gary Ocock at 100 yards in a California benchrest match on August 6, 2017. Though Gary’s 0.0840 Agg beats existing records, this was not a “sanctioned” match, so Gary’s killer Agg will NOT be submitted for IBS or NBRSA records. So, sadly, the Agg won’t appear in the record books, but this remains a spectacular, verified feat of rifle accuracy, accomplished in competition.
Gary’s red railgun is arguably the Most Accurate Gun Ever Built. As far as we can determine, no one has ever shot a smaller 5-target Agg anywhere, at any time. FYI, the NBRSA Unlimited Class 5×5 Aggregate World Record is 0.1242″ shot by Jerry Lahr in 2012. Gary’s 0.0840″ Agg is much smaller.
The Unlimited Benchrest Record That Will Never Be (Official)
Report by Boyd Allen
Gary Ocock’s stunning unlimited Aggregate is beyond amazing. That’s an average of five, 5-shot groups of .0840. Shot under sanctioned match rules, but at an unsanctioned 100-yard fun match, this Aggregate is well under the current 100-yard official records of the IBS (.1386), and the NBRSA (.1242). The fourth of the five groups measured a minuscule .018, less than half the size of the existing NBRSA Unlimited record of .049 (also shot by Gary). Check it out:
When the top 15 shooters all post teen Aggs, conditions must be pretty favorable. However there were some light switchy winds — Gary said that he shot better in the left to right condition.
GUN SPECIFICATIONS
Ocock’s red Jay Young Unlimited Railgun features one major difference from Young’s typical Railgun designs. The bottom of the barrel block is integral with the top (moving part), of the gun. The barrel is Ocock’s usual 1:13.5″-twist Krieger chambered for the 6 PPC. The BAT Neuvo action* is unusual in that its lugs are horizontal at lock-up instead of the usual vertical. With horizontal lugs, both lugs maintain contact with their abutments when the action is cocked. In the more normal configuration when cocked the top lug is forced off of its seat by a combination of the angle of the trigger cocking piece interface, the pressure of the striker spring, and bolt clearance at the rear of the action.
LOAD SPECIFICATIONS
Gary shot this remarkable Agg with well-used brass, Vihtavuori N133 powder, and self-made 66gr BT bullets** seated at “jam”. This amazing Agg was shot on the second day of a 2-day Unlimited Benchrest match. On Day 1 Gary had experimented with various loads using both surplus IMR 8208 and Vihtavuori N133, but was not satisfied with the results. For his first group on Day 2, Gary tried a light load of N133. After seeing the result, however, he decided to go to the other extreme — a super stout N133 load — with the same powder. As you can see, Gary’s willingness to experiment paid off.
Notably, Gary used light neck tension. Ocock found that for these bullets and this barrel, light neck tension worked best (contrary to “normal” N133 benchrest practice). Ocock used a bushing that only produces .001″ difference between the diameters of sized and loaded case necks.
This video shows a line-up of Rail-Guns. One of Gary Ocock’s Rails appears at the 0:35 time-mark.
Comment on Ocock’s Achievement
Congratulations to Gary Ocock for superb shooting (and smart loading). Even though the match was not sanctioned (so the Agg will never be a record), Ocock has raised the bar very high, and given us a new standard of ultimate accuracy.
Though this 0.0840 Aggregate and 0.018 group will never go into the record group, they are still noteworthy. There’s virtually no doubt that they would have survived inspection by any record committee. Except for the lack of fixed backers, an IBS requirement (for detecting cross-fires), all other conditions were met for an officially-sanctioned match.
Ocock Did Set Single-Group IBS World Record with Red Railgun
Photo credit: Ben Zentner
Here is Gary with his Red Railgun at a Visalia event in October 2017. Ocock let the event’s youngest competitor, 12-year-old Gavin Lichtenwalter, shoot Gary’s new Railgun for the last three matches on Sunday afternoon. The day before, 10/21/17, Gary shot an IBS Heavy Benchrest World Record putting five shots in just 0.045 inches, as certified by the IBS record committee. Here is that group, as first measured at the range at 0.039 inches.
*The new BAT Neuvo actions are the result of a collaboration between Dwight Scott, and Bruce Thom, featuring Dwight’s ideas and BAT’s proven manufacturing expertise.
** Ocock shot his own, boat-tail match bullets, made with George Ulrich-crafted dies using Hood cores. Although he said that it had been a while since he had weighed any, his best guess was that they weigh something around 66.5 grains.
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When he measures his loads or sorts bullets by weight, Forum Member Boyd Allen often employs his trusty RCBS 10-10 balance beam scale (although he does have handy digital scales as well). He finds that the balance beam scale works predictably, time after time, and it doesn’t suffer from the drift and calibration issues that plague some of the less expensive electronic scales on the market.
To make it easier to see the balance point, Boyd has adapted a magnifying glass with a mirror. This makes the end of his balance beam easier to view from his normal position on the bench. Boyd explains: “This set-up uses a cheap magnifier with positioning arms that was probably designed to hold and magnify small objects while soldering them. I think that it came from Harbor Freight many years ago. The mirror lets you look at the scale as if is was at eye level, and of course the magnifier makes the image easier to see.”
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Want to see the details?CLICK HERE to view full-screen photo.
Five targets, each with FIVE shots in essentially one hole. The events of this story happened two years ago. We are reprising our report because this five-target Aggregate arguably represents the most impressive feat of 100-yard accuracy in the history of marksmanship on this planet.
Check out those five targets. The Aggregate (average) of all five targets is a tiny 0.0840 inches! These were shot by Gary Ocock at 100 yards in a California benchrest match on August 6, 2017. Though Gary’s 0.0840 Agg beats existing records, this was not a “sanctioned” match, so Gary’s killer Agg will NOT be submitted for IBS or NBRSA records. So, sadly, the Agg won’t appear in the record books, but this remains a spectacular, verified feat of rifle accuracy, accomplished in competition.
The argument can be made that this is the Most Accurate Gun Ever Built. As far as we can determine, no one has ever shot a smaller 5-target Agg anywhere, at any time.
The Unlimited Benchrest Record That Will Never Be (Official)
Report by Boyd Allen
Gary Ocock’s stunning unlimited Aggregate is beyond amazing. That’s an average of five, 5-shot groups of .0840. Shot under sanctioned match rules, but at an unsanctioned 100-yard fun match, this Aggregate is well under the current 100-yard official records of the IBS (.1386), and the NBRSA (.1242). The fourth of the five groups measured a minuscule .018, less than half the size of the existing NBRSA Unlimited record of .049 (also shot by Gary). Check it out:
When the top 15 shooters all post teen Aggs, conditions must be pretty favorable. However there were some light switchy winds — Gary said that he shot better in the left to right condition.
GUN SPECIFICATIONS
Ocock’s red Jay Young Unlimited Railgun features one major difference from Young’s typical Railgun designs. The bottom of the barrel block is integral with the top (moving part), of the gun. The barrel is Ocock’s usual 1:13.5″-twist Krieger chambered for the 6 PPC. The BAT Neuvo action* is unusual in that its lugs are horizontal at lock-up instead of the usual vertical. With horizontal lugs, both lugs maintain contact with their abutments when the action is cocked. In the more normal configuration when cocked the top lug is forced off of its seat by a combination of the angle of the trigger cocking piece interface, the pressure of the striker spring, and bolt clearance at the rear of the action.
LOAD SPECIFICATIONS
Gary shot this remarkable Agg with well-used brass, Vihtavuori N133 powder, and self-made 66gr BT bullets** seated at “jam”. This amazing Agg was shot on the second day of a 2-day Unlimited Benchrest match. On Day 1 Gary had experimented with various loads using both surplus IMR 8208 and Vihtavuori N133, but was not satisfied with the results. For his first group on Day 2, Gary tried a light load of N133. After seeing the result, however, he decided to go to the other extreme — a super stout N133 load — with the same powder. As you can see, Gary’s willingness to experiment paid off.
Notably, Gary used light neck tension. Ocock found that for these bullets and this barrel, light neck tension worked best (contrary to “normal” N133 benchrest practice). Ocock used a bushing that only produces .001″ difference between the diameters of sized and loaded case necks.
Comment on Ocock’s Achievement
Congratulations to Gary Ocock for superb shooting (and smart loading). Even though the match was not sanctioned (so the Agg will never be a record), Ocock has raised the bar very high, and given us a new standard of ultimate accuracy.
Though this 0.0840 Aggregate and 0.018 group will never go into the record group, they are still noteworthy. There’s virtually no doubt that they would have survived inspection by any record committee. Except for the lack of fixed backers, an IBS requirement (for detecting cross-fires), all other conditions were met for an officially-sanctioned match.
*The new BAT Neuvo actions are the result of a collaboration between Dwight Scott, and Bruce Thom, featuring Dwight’s ideas and BAT’s proven manufacturing expertise.
** Ocock shot his own, boat-tail match bullets, made with George Ulrich-crafted dies using Hood cores. Although he said that it had been a while since he had weighed any, his best guess was that they weigh something around 66.5 grains.
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Here is a simple, low-cost way to get reliable readings of case headspace when you “bump” the shoulder back on your 6BR, .243 Win, or .308 Win brass. Credit Boyd Allen for this tip. First, you’ll need one .45 acp case, with primer removed. Make sure the .45 acp case is trimmed square and that it is round. We recommend you first run it through an expander, then size it, trim it and chamfer. Next, take the .45 acp case and slip it over the neck of a fired, unsized rifle case with the primer removed. Align the two cases between the jaws of your calipers and note the length from rim to rim (See photo below, with striped case).
OK, now you have the length for a fired rifle case BEFORE sizing. Next, take a full-length sized rifle case (without primer) and do the same thing, placing the .45 acp case over the neck of the FL-sized case (Bottom Photo). The difference between the two numbers is the amount of “bump” or set-back you are applying to the shoulder. Here the difference is .0015″. The amount of bump you need varies with your chamber and your load, but .0015-.002″ is a good initial setting. By using this simple tool, you can avoid bumping the shoulder too much. This will also help you set-up the depth of your full-length die to get the proper amount of bump each time.
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The way you drop powder in the case will affect your max powder volume and the load density. Look at the photo above. These photos show the SAME 30.6 grains of powder using four different fill methods. If you are working with a powder that is below max safe pressure at your current “full case” (with room left for the bullet), and you want to get more velocity with that powder, consider a different case-filling technique.
Most of us assume that if we weigh our powder carefully (down to the tenth of a grain or less) we can achieve a uniform powder fill from case to case in our handloads. Weighing does ensure that the weight of the propellant in each case is the same, but is the column of powder the same by volume each time? “Not necessarily” is the answer. An interesting experiment by our friend Boyd Allen demonstrates that the manner in which you place kernels in the case can make a significant difference in the height of the powder column within the brass case.
Using a Gempro 250 scale, Boyd measured exactly 30.6 grains of Vihtavuori N-133 powder. He then inserted this powder in the same cartridge case multiple times. (The case has a fired primer in place.) But here is the key — Boyd used various filling techniques. He did a slow fill, and a fast fill, and he also experimented with tapping and drop tubes. What Boyd discovered was that you can start with the exact same weight of powder (in fact the very same set of kernels), yet end up with vary different fill heights, depending on how you drop the kernels into the case. Look at the photos. Despite variations in lighting, the photos show the same 30.6 grains of powder, placed in the same cartridge, with four different methods.
Using funnels with long drop tubes packs kernels more tightly, creating a shorter powder column. That allows you to get more propellant (by weight) into the case.
Boyd Explains the Procedure Used for his Experiment.
EDITOR’s NOTE: So there is no misunderstanding, Boyd started with a weighed 30.6 grain charge. This identical charge was used for ALL four fills. After a fill the powder was dumped from the case into a pan which was then used for the next fill technique to be tried. So, the powder weight was constant. Indeed the exact same kernels (of constant weight and number) were used for each fill.
Boyd writes: “I used the same powder for all fills, 30.6 gr. on a GemPro 250 checked more than once. All fills employed the same RCBS green transparent plastic funnel. The fast drop with the funnel only overflowed when it was removed from the case neck, and 15 granules of powder fell on the white paper that the case was sitting on. The fast-funnel-only drop with tapping, was done with the funnel in place and the case and funnel in one hand, while tapping the case body with the index finger hard, many times (about 20 fast double taps). My idea here was to “max out” the potential of this tapping technique.
The slow drop with the funnel and 10″-long .22 cal. Harrell’s Precision drop tube, was done by holding the scale pan over the funnel and tapping the spout of the pan repeatedly on the inside of the funnel about 1/3 down from the top, with the scale pan tilted just enough so that the powder will just flow. Many taps were involved, again, to max out the technique.
Again, to be clear, after each case filling, the powder was poured from the case back into the scale pan carefully. You may notice the similarity between the fast drop with the drop tube, and the funnel only with tapping. Although I did not photograph it, fast tube drop and tapping (combined) improved on tapping alone, but only to about half as far down the neck as the slow with drop tube. Due to the endless possible permutations, I picked four and left it at that.
I believe that I can make the rough judgment that the scale pan funnel and drop tube technique, which involved a longer drop period, and probably less velocity at the top of the tube, left more room in the top of the case neck than the slow drop from the measure with the same drop tube. You have both pictures, so you can make the comparison.” — Boyd
Does Powder Column Height Variance Make a Difference?
Boyd’s experiment proves pretty conclusively that the method of dropping a given weight of powder can affect the height of the powder column in the case and the degree of powder compression (when a bullet is seated). He showed this to be true even when the exact same set of kernels (of constant weight) was used in repetitive loadings. This raises some interesting questions:
Check out those five targets. The Aggregate (average) of all five targets is a tiny 0.0840 inches! These were shot by Gary Ocock at 100 yards in a California benchrest match on August 6, 2017. Though Gary’s 0.0840 Agg beats existing records, this was not a “sanctioned” match, so Gary’s killer Agg was NOT submitted for IBS or NBRSA records. So, sadly, the Agg won’t appear in the record books, but this remains a spectacular, verified feat of rifle accuracy, accomplished in competition.
Check out those five targets. The Aggregate (average) of all five targets is a tiny 0.0840 inches! These were shot by Gary Ocock at 100 yards in a California benchrest match on August 6, 2017. Though Gary’s 0.0840 Agg beats existing records, this was not a “sanctioned” match, so Gary’s killer Agg will NOT be submitted for IBS or NBRSA records. So, sadly, the Agg won’t appear in the record books, but this remains a spectacular, verified feat of rifle accuracy, accomplished in competition.
