Originally Posted by Marine sniper
3200 from a 300 UM, sounds prety warm! I did not think they were that much more than a 300 Weatherby. I get just over 3000 ft from 80 grs. of 7828 25.5 in barrel and I am killing my brass to do it.
.120 off the lands ? Hmm,. I have always thought you "had" to put the Bergers right in the lands to get them to shoot. What is this "new" Berger 210 ?
What did the BC work out to be?
The load is warm for sure but the primers keep going back in. H1000 is quite a bit slower than IMR7828 and IMR7828 has a pretty quick pressure curve comparatively. That could explain why your brass is hammered.
I have always jammed Bergers into the lands myself but the last few guns I've worked on seemed to shoot fine with the bullets seated to fit the magazines. They are jumping more than I would like but it seems they can be tuned for it.
The new Bergers are being made with more exacting tolerances and many guys are reporting bearing surface variations are being held to less than .002" just like what I've seen so far. No more bullet segregating!
I only had took one of my chronographs to the range today so I can't say exactly yet what the bc was but it was absolutely dead calm this morning at 5:30 so I got a pretty good read for backfiguring the bc and it came out at .725. This is quite a bit higher than the rated .631 and even the old rating of .64. I will more accurately figure the bc with two chronos next time but I can say for sure that it was certainly over .67 and .725 matched the drops perfectly. This barrel is very smooth and seems to produce crazy bc's but more testing is in order.