Its been normal for a new barrel to make a velocity increase usually from 50 to have had as many as 150 shots on it when I see it occur. Have seen speed go up 100fps on occasion but about 50fps seems more the norm.
More DRT bang flops than any other caliber I own with the 7RM. Running 140 AB at 3300fps from 26" barrel sendero, .075 off the lands with RL26. None of the issues described above and accounted for 100's of deer size animals. 2nd target overlay of 1st target included.
With Hornady making 7 wsm brass that opens new window for my old flat top savage 7wsm, if anyone has time please run QL for me with RL 23. Thank You!!!
7WSM
140 Accubond
24" Barrel
OAL 2.83
Fed GM215M primer
Run with RL 23 please.
I'm excited to build a load for this thing......
Looks like as long as you keep speeds under 3000 with H4350 you are below 60kpsi. Keep in mind that Optimum barrel time for 22" barrel in this speed range with H4350 is 1.12 ms or in this instance 2934fps which will give approx 56kpsi. Let magnetospeed guide you.
Cartridge : .243 Win.
Bullet ...
90 Accubond is 1.11 length with about .140 plastic tip. If you ONLY going to shoot tipped bullets you will be fine with a 9 twist.
Any longer bullets or bullets of same length without plastic tip and you will need to be tad faster twist is what I have found.
The 90 AB and the 95BT are both longer (1.110 to 1.115"" approx)and I have never gotten them to shoot great in a 10 twist. The 90BT is shorter (1.071") and should shoot very well in the 10 twist. The 90BT is stable to near 0 degrees in a 10 twist...
+1!
I had older Norma made Nosler brass for 7RM that averaged 216-218 grains. Also a old bucket full of Norma headstamp that weighs in same range.
Then buy new batch of Nosler expecting the same quality as past and Nosler brass weighed 256 grains. BIG change went down. Now just buy Norma and...
IMR or H4198 look for speed at 2,100 start at 47 grains. However I have found AA 2015 to be more accurate but look speed at 2,100 start at 54 grains.
With either powder just work to chrono speed of 2100 and you be gtg.
Yes new barrels will speed up but in this case powder choice may be attributing as well.
IMR4831 can show swings in speeds depending on load, cartridge bullet weight, primer etc. lots of variables but on average across different calibers I see IMR4831 change speed along the lines of 1.5 fps per...