February 6th, 2010

Mock Demonstrates IMR 8208 XBR Accuracy and Wide Load Window

The new IMR 8208 XBR powder is quickly acquiring a reputation for accuracy and pressure stability over a very wide range of temperatures. In addition, it looks like 8208 XBR has a huge load window for accuracy, at least in the 6 PPC cartridge. Here are five successive targets shot by journalist James Mock. With loads range from 30.5 grains to 31.5 grains, Mock nailed five “zero” groups in a row. (These were all three-shot groups.) Mock nailed “zeroes” over a full grain load-weight spread. That’s very impressive, and it bodes well for those who want to spend less time “tuning” their loads.

IMR 8208 XBR powder

James observes: “[Here are] 5 consecutive ‘zeroes’ with charges from 30.5 to 31.5. I used a Krieger barrel (583 rounds) and a BAT Model B action. The bullets are from Del Bishop. I used both Wolf SR and Fed 205 primers.The combination that I used that day was really working. The Bishop 65 grain FB bullets were seated to just touch the lands in a barrel with 583 rounds.”

Permalink Competition, Reloading 2 Comments »
December 17th, 2009

Jackie Schmidt Tests New IMR 8208 XBR Powder — Results are Very Impressive

IMR 8208 XBR is a new powder to be released by Hodgdon in January, 2010. The powder is said to be extremely accurate, and Hodgdon believes it will set new standards for stability across a wide temperature range. We spoke to Chris Hodgdon last week and he confirmed that “the 8208 XBR is packaged and ready to go. We plan to start shipping in quantity starting January 4th”.

Schmidt Tests IMR 8208 XBR with 6 PPC Railgun
Is the new powder as good as early reports have suggested? Ace Benchrest shooter Jackie Schmidt recently tested IMR 8208 XBR with his 6PPC rail gun. The results were very impressive. (Test observer 333 Smitty said: “This was the best testing session I have ever witnessed — It looks like the new 8208 is a huge success!”)

IMR 8208 XBR test Schmidt

Shooting five, 5-shot groups, Jackie put together an .0976 Agg. His last two groups, both using weighed 8208 XBR loads, were in the zeros. (See target photo.) Jackie was shooting his Unlimited Rail with 65gr “Bartail” bullets, Fed 205 primers. The barrel was a 23.5″ straight-contour Kreiger with a 1:13.5″ twist. Conditions were “were really nice, just a gentle ebb and flow” with temps in the 50s and about 60% humidity.

Here is Jackie’s report, originally posted in the Benchrest Central Forum:

“I first started out with my ’08 Vihtavuori N133, just to see if the Rail was on its game. After a few 3-shot groups to find the window, I settled in on 30.4 grains with a 65gr Barts Boattail. I then nailed a nice 5-shot ‘zero’ that you can see on the far left, second row up. Average velocity was 3470 fps.

I then switched over to the 8208 XBR. I started with a load that Tom Libby recommended, 31.3 grains. While it did not nail a ‘zero’, you can see it shot pretty well. The average velocity for the five record shots was 3430 fps.

I then decided to drop the load down into another window, a flat 30.0 grains. The average velocity was 3320, and as you can see, the group opened up. I felt like I hit the condition just right on each shot. Maybe a little cool for this light of a load.

IMR 8208 XBR test Schmidt

We then decided to up the charge until it matched the velocity of the N133. This took 31.8 grains. With a slow trickle this was just about half-way up into the neck. The group was really nice, so I decided to try the load again, only weighing each charge. The results were the group you see on the far right. That is really probably about a .040″, pretty darned small. The average velocity on both groups was about 3470 fps.

I then decided to go back to the 31.3 grain charge, but weighing each charge this time. The results were another nice “zero”. The velocity was the same as before, but the total spread on this group was only 12 fps.”

IMR 8208 Also Shoots Well in Sporter Rifle
Jackie reports: “I then pulled out my Sporter, and put the 31.8 grain XBR load in. I shot a couple of 3-shot groups that were about .110, then shot a 5-shot group that was a ‘zero’ for the first four. But I missed the last condition, and opened it up to about a .180, straight to the right.”

IMR 8208 XBR test Schmidt

Observations and Conclusions
Jackie writes: “So, what did I find out? First, this stuff is more dense than N133. I can barely get the 30.4 grain N133 load in the case, but there is no problem at all getting the XBR in at darned near 32.0 grains. This shows that, by weight, XBR is slower than the ’08 N133.

The 8208 XBR also burned just as clean as N133. I could not tell the difference in the patches that came out after shooting N133 and the XBR. Also, this stuff meters VERY WELL. Much more consistant than N133. While I started weighing charges, I could count on the XBR out of my Hensler Measure to be within ± 0.1 grain. I simply cannot do this with N133.

An added note, the Rail Gun has a 23 1/2 inch barrel, the Sporter a 21 1/2. With the same load, I saw an average 70 to 80 fps slower velocity out of the shorter barrel. These two barrels are just about identical in the land and groove diameter, both .237 4-groove Kriegers[.] I guess this shows that some of the powder is still burning at 21 1/2 inches.

I showed that yes, at 52 degrees overcast and dreary, I made the stuff shoot pretty darned good. But, I do not have a clue what will happen when the weather changes. Only time will tell.

That about covers it. This new powder will shoot, and velocity is certainly not a problem. I had zero problems with any pressure signs, the handle on the Diamondback on the Rail and the Bat action on the Sporter lifted really easy on all loads, and the primers looked nice, with a generous radius still on the outside edge.”

General Comments — Can 8208 XBR Live Up to Expectations?

Jackie offered these general thoughts about IMR 8208 XBR and how it stacks up versus Vihtavuori N133:

“I have been shooting Benchrest since the mid ’90s, and I can’t think of a single product causing this much excitement, or generating this much hype. Just what are everyone’s expectations? Being able to arrive at a competitive tune, and have it stay there all day? Being able to shoot in the upper window without wrecking the brass? Being able to concentrate on the actual ‘shooting’ rather than worrying about the rifle going ‘vertical’ at any moment?

As of now, a few shooters have been able to test this new powder and found it to be capable of producing good velocity, and great groups. But, the realities of the ‘Competitive Arena’ can be very harsh. Nothing is more aggravating than trying to keep up with the pack when your rifle is locked into a .300 tune, and try as you do, nothing seems to work. We have all been there.

My expectations are that the new powder will be more stable in the perameters that govern that all important ‘Agging Capability’. By that I mean that if the rifle does get a little ragged, just a little tweek one way or another will get it back. Or even better, that the rifle will stay reasonably competitive over a day’s worth of aggregates without fear of getting so ragged that your entire day is ruined by two bullet holes worth of vertical.

This is a tough sell. But then, this is a tough game. I, for one, really hope that this new powder is more ‘user friendly’, so Benchrest can get back to being more about shooting, rather than chasing loads all day long.

N133 is probably the most used powder in 100-200 yard Benchrest today. It is also, at the same time, the biggest source of aggravation. If it is right, nothing can beat it. But, as we all know, if it isn’t quite right, the fun can go away real quick. One of the Holy Grails of Benchrest has always been how to make N133 shoot over an entire Aggregate.”

Photos Courtesy G.A. Villarreal, used with permission.

Permalink Bullets, Brass, Ammo, Gear Review, New Product 2 Comments »