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Post by mosigdude on Jun 5, 2016 13:17:58 GMT -8
I picked up a 20" 1/8 Twist BHW barrel in 260 Rem a few months ago and finally got around to completing the build. This is my first 308-platform build so I kept it pretty simple with a set of Aero receivers, a black rain trigger that I had sitting around, a BTE adjustable gas block and all the other parts were pretty basic including an unknown-brand FF Tube for the front.
Brass is all formed from once-fired RP 308 Match without a lot of prep into them other than sizing them to 7mm-08 and then 260 Rem as a final step. I had a canister of IMR4350 sitting around that I didn't have much use for since most of my rifles that would use this powder show a distinct preference for H4350 so I decided to burn this up, picked a load several grains below max and loaded up my barrel break-in loads with this charge under a Sierra 120gr BTHP MatchKing.
I spent the first wave of loads getting the optics and rifle together on paper, adjusting the bas block for proper function and just settling into the rifle. Although I wasn't trying especially hard, considering there was no workup whatsoever on this load, I noticed I was shooting pretty tiny groups at 100 so I put the last 3 rounds of the break-in to the test and let the new build eat at 200 yds. I'm getting 0.53" on the measurement. Thank you BHW for another great build!
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Post by peabody on Jun 5, 2016 19:49:37 GMT -8
That is a most-impressive group! I have a great fetish for the 6.5 calibers and have toyed with the idea of a build on the AR10-class platform. Seeing results like yours doesn't help keep my wallet safe, though. Looking forward to more data on your system...
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Post by GLSHOOTER on Jun 6, 2016 6:03:15 GMT -8
I feel like Sulu, "Oh My"
Greg
Just a suggestion. Put the calipers on the outside of the holes and that will give you a much better reading across the board after doing the math.
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Post by mosigdude on Jun 6, 2016 9:26:09 GMT -8
I actually started with them on the inside of one hole and outside of the furthest and then locked the calipers down for the same effect. I just moved the calipers to the center of the holes for visual effect.
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Post by GLSHOOTER on Jun 6, 2016 9:41:40 GMT -8
I actually started with them on the inside of one hole and outside of the furthest and then locked the calipers down for the same effect. I just moved the calipers to the center of the holes for visual effect. Camera angles can really screw up perception on measuring groups. Some claims,not you by any means, always seem abit overly optimistic. I saw one last week that was a three shoter claiming XXX but you could clearly see where instead of the two bullet size that you could fit two bullets in between the furthest two. Not as small as claimed. On neat thing is you can take groups and blow them up on your monitor and measure them. I do that a lot..LOL Greg |
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Post by mosigdude on Jun 6, 2016 17:10:28 GMT -8
I have seen some of the same 'out there' claims, complete with accompanied pictures to refute them. I almost have to believe a little of it is accidental ignorance and just not measuring right. I keep mine honest, I try to post pictures of the good ones and talk about the bad ones in print... after all, no one wants a pic of an ugly group, but I genuinely believe there's value in knowing the details of the best and worst alike.  |
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Post by GLSHOOTER on Jun 6, 2016 18:10:39 GMT -8
I have seen some of the same 'out there' claims, complete with accompanied pictures to refute them. I almost have to believe a little of it is accidental ignorance and just not measuring right. I keep mine honest, I try to post pictures of the good ones and talk about the bad ones in print... after all, no one wants a pic of an ugly group, but I genuinely believe there's value in knowing the details of the best and worst alike. Yep. Some ignorance but lots of smoke and mirrors. The barrels that ALWAYS are sub-MOA but you never see a group or the guys on work ups that have consistent 0.4 and 0.6 groups across a grain and a half of powder. Then you notice they are at 74 yards. No group pictures. They post speeds that are consistently higher than identical bore and capacity cases can reach safely yet they never have pressure signs and have never blown a primer. Of course they conveniently forget to mention case life. Yiu find huge velocities posted and find those are shot out of 26" barrels with loads that were too hot to handle with NOMEX gloves before they were shot. I've spent half a century watching and studying the snake oil salesmen of the gun world. It will never change and only the light of a calipers, a camera and a pressure gauge will blow away the smoke. Greg |
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Post by ChiefPlumber on Jun 24, 2016 8:04:02 GMT -8
No need for calipers...unless you're just into the fractionals. Given the target background, it's clear to me this is an ~0.50" group(assuming 1" squares). Great shooting. I've an Aero M5 set I'm still deciding on caliber. I'm waffling between .260 and .308 There is still an outside chance of a .338.
Regards,
CP
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