June 22nd, 2019

The Most Incredible Accuracy in History — But It’s Not a Record

Gary Ocock Rail Gun Unlimited Target Visalia CA 6 PPC IBS NBRSA
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:

Gary Ocock Rail Gun Unlimited Target Visalia CA 6 PPC IBS NBRSA

Gary Ocock Rail Gun Unlimited Target Visalia CA 6 PPC IBS NBRSA
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.

Gary Ocock Rail Gun Unlimited Target Visalia CA 6 PPC IBS NBRSA

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.

Permalink - Articles, Bullets, Brass, Ammo, Competition, Shooting Skills 7 Comments »
June 22nd, 2019

Reloading Basics: Neck Tension, Expander Balls, and Bushings

Case Loading Neck Tension Sierra Bullets Paul Box

by Sierra Bullets Ballistic Technician Paul Box
One thing that plays a major role in building an accuracy load is neck tension. I think a lot of reloaders pretty much take this for granted and don’t give that enough thought.

So, how much neck tension is enough?

Thru the years and shooting both a wide variety of calibers and burn rates of powder, I’ve had the best accuracy overall with .002″ of neck tension. Naturally you will run into a rifle now and then that will do its best with something different like .001″ or even .003″, but .002″ has worked very well for me. So how do we control the neck tension? Let’s take a look at that.

First of all, if you’re running a standard sizing die with an expander ball, just pull your decapping rod assembly out of your die and measure the expander ball. What I prefer is to have an expander ball that [can give] you .002″ in neck tension [meaning the inside neck diameter is about .002″ smaller than the bullet diameter after passing the expander through]. If you want to take the expander ball down in diameter, just chuck up your decapping rod assembly in a drill and turn it down with some emery cloth. When you have the diameter you need, polish it with three ought or four ought steel wool. This will give it a mirror finish and less drag coming through your case neck after sizing.

Tips for Dies With Interchangeable Neck Bushings
If you’re using a bushing die, I measure across the neck of eight or ten loaded rounds, then take an average on these and go .003″ under that measurement. There are other methods to determine bushing size, but this system has worked well for me.

Case Loading Neck Tension Sierra Bullets Paul Box

Proper Annealing Can Deliver More Uniform Neck Tension
Another thing I want to mention is annealing. When brass is the correct softness, it will take a “set” coming out of the sizing die far better than brass that has become to hard. When brass has been work hardened to a point, it will be more springy when it comes out of a sizing die and neck tension will vary. Have you ever noticed how some bullets seated harder than others? That is why.

Case Loading Neck Tension Sierra Bullets Paul Box

Paying closer attention to neck tension will give you both better accuracy and more consistent groups.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 7 Comments »