goodgrouper
tryingtobeabettergrouper
I had the good fortune of getting down to the Phoenix benchrest match this past weekend a day early so I could do some practicing. So I decided to setup my Oehler 35 chronograph and test my temperature/powder setting chart for accuracy at the roughly 1600 foot elevation of the Ben Avery range and the temperature of 80 degrees.
After confirming the data, I happened to walk past my buddy Larry L.'s loading bench and saw he had a gold labeled powder bottle sitting on his table. I had to see if my eyes had deceived me. They hadn't. Larry was in possession of about half a pound of the new IMR8208xbr powder. So I went over to talk to him about it. After chatting a minute or two, he suggested we chrono some of it and make a comparison to N133. I had some '07 N133 in my hopper and was throwing about 28.2 grains so Larry got out his scale and weighed out 28.2 grains of the gold label powder. I put it into my cases between some Wolf MSR primers and some Bruno 68 oo Bt bullets. I had five rounds of each and commenced to shoot them over the chrono.
Now, before I give the results, I had better back up a bit. I went down to this match with two barrels that were on their lasts legs. My freshest barrel was a Bartlein that had about 1550 rounds through it and the other barrel was a Krieger with 1700+ rounds through it. So I figured I would shoot the Bartlein in the match and shoot the Krieger for my powder testing. The Krieger still seems to shoot quite well but it's not near as good as it used to be. However, the first group with the IMR8208xbr load was quite surprising. I never went downrange to measure it but it was certainly in the low ones and four of the five were around a mid zero! This group was the best group the barrel shot all day and it was good enough to make me forget about the fact that the chronograph said it was only going 3022 feet per second! The same charge of N133 (28.2) went through the chrono at 3245 fps. That's a difference of over 200 fps!! Wow.
Now Larry said that he had been shooting 31.1 grains of the gold label stuff through his gun and it really shot well with that load so I had him throw me five more charges at that weight into my cases. I was amazed to see that 31.1 grains came about half way up the neck of my ppc Lapua brass! It is definitely packing tighter in the case than N133 does. I can't get 31 grains of N133 in there even with an 8" drop tube. XBR easily fits and would probably be able to go as high as 31.8 grains or so.
Anyway, I seated the Bruno's and went to the line. The heavier charge shot 3388 fps and there was no pressure. That's quite a jump of velocity. The group wasn't all that great but that is not the powder's fault. I have never had good groups with oo Bt bullets pushed over 3300 fps in three different barrels I've tried them in so it was no surprise here. But for a different bullet, I think you could easily attain 3450 or better and probably see no pressure signs.
I was quite impressed with the new powder. It seems to have been specifically designed to fill up a Lapua brass to the neck half-way mark with an above 30 grain load yielding great velocity with substantially less peak pressure. And it was noticeably cleaner burning than N133 too.
Come January, I hope to get my hands on my very own gold label bottle and do some more testing..............
In the meanwhile, thanks to Larry for letting me use some of your pixie dust.
After confirming the data, I happened to walk past my buddy Larry L.'s loading bench and saw he had a gold labeled powder bottle sitting on his table. I had to see if my eyes had deceived me. They hadn't. Larry was in possession of about half a pound of the new IMR8208xbr powder. So I went over to talk to him about it. After chatting a minute or two, he suggested we chrono some of it and make a comparison to N133. I had some '07 N133 in my hopper and was throwing about 28.2 grains so Larry got out his scale and weighed out 28.2 grains of the gold label powder. I put it into my cases between some Wolf MSR primers and some Bruno 68 oo Bt bullets. I had five rounds of each and commenced to shoot them over the chrono.
Now, before I give the results, I had better back up a bit. I went down to this match with two barrels that were on their lasts legs. My freshest barrel was a Bartlein that had about 1550 rounds through it and the other barrel was a Krieger with 1700+ rounds through it. So I figured I would shoot the Bartlein in the match and shoot the Krieger for my powder testing. The Krieger still seems to shoot quite well but it's not near as good as it used to be. However, the first group with the IMR8208xbr load was quite surprising. I never went downrange to measure it but it was certainly in the low ones and four of the five were around a mid zero! This group was the best group the barrel shot all day and it was good enough to make me forget about the fact that the chronograph said it was only going 3022 feet per second! The same charge of N133 (28.2) went through the chrono at 3245 fps. That's a difference of over 200 fps!! Wow.
Now Larry said that he had been shooting 31.1 grains of the gold label stuff through his gun and it really shot well with that load so I had him throw me five more charges at that weight into my cases. I was amazed to see that 31.1 grains came about half way up the neck of my ppc Lapua brass! It is definitely packing tighter in the case than N133 does. I can't get 31 grains of N133 in there even with an 8" drop tube. XBR easily fits and would probably be able to go as high as 31.8 grains or so.
Anyway, I seated the Bruno's and went to the line. The heavier charge shot 3388 fps and there was no pressure. That's quite a jump of velocity. The group wasn't all that great but that is not the powder's fault. I have never had good groups with oo Bt bullets pushed over 3300 fps in three different barrels I've tried them in so it was no surprise here. But for a different bullet, I think you could easily attain 3450 or better and probably see no pressure signs.
I was quite impressed with the new powder. It seems to have been specifically designed to fill up a Lapua brass to the neck half-way mark with an above 30 grain load yielding great velocity with substantially less peak pressure. And it was noticeably cleaner burning than N133 too.
Come January, I hope to get my hands on my very own gold label bottle and do some more testing..............
In the meanwhile, thanks to Larry for letting me use some of your pixie dust.
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