140's at 2850fps from 22" AR10 safe? Plus dual Load development and data.

[1jonathan1994]

I have and Aero/JP 6.5 Creedmore. 22" with XL gas. When i first built it it was 3/4 to 1moa with factory 140's running about 2650fps. Now 400rounds later its shooting the same ammos well over 1 moa at around and over 2700fps. So I am getting into reloading and want to make sure im on the right track and not about the blow myself up.

FIrst the Berger 140Hybrid load. Top row was near the coldest. Bottom right was hottest. In between not shown.

And the 500yd target

H4350. CCI primer. Hornady brass. 140 Berger Hybrids loaded 2.835" (magazine length). about 0.110" - 0.120" jump. 500yds, 60F, Left to right wind and bad mirage.
grains - fps - impact point from bottom of target
39gr 2505 chrono @ 100yds
39.5 oops shot the camera tripod down. used windage (in) for elevation (mil)...
40.0 2576 10.7
40.3 2585 8.7
40.6 2608 12.8
40.9 2629 13.7
41.2 2654 16.3 low node?
41.5 2671 16.5 low node
41.8 2676 16.9 low node
42.1 2697 13.4
42.4 2724 18.2
42.5 2735 14.3
42.8 2739 16.9 high node
43.0 2777 17 high node
43.2 2790 18.6 high node
43.5 2815 23.8 !!!! from a 22" barrel. Is this not too fast to be safe????
43.7 oops 23.8 All cases came out of the gun with an easy pull of the charging handle. I had the gas turned off.

Now the Hornady brass. Top row cold. Bottom right hottest.

Hornady 500yd target

H4350. CCI primer. Hornady brass. 140 ELD-M's loaded 2.835" (magazine length). about 0.025" - 0.030" jump. 500yds, 60F, Shifting breeze.
grains - fps - impact point from bottom of target
39.4 2573 chrono
39.7 2585 chrono
40 2602 chrono
40.3 2637 9.4
40.6 2640 11.7
40.9 2655 8 low node?
41.2 2663 8.8 low node
41.5 2695 9.9 low node
41.8 2693 9.6 low node
42.1 2733 12.7
42.4 2744 10.1
42.7 2757 12.4 high node
43.0 2785 13.5 high node
43.3 2778 14.3 high node
43.6 2819 12.1 high node
43.9 2845 15.4 all brass removed with an easy pull of the charging handle. GAs turned off.

and the plot of powder vs velocity and vertical height on target

Its obvious both bullets have a low node around 2675fps and 41.6 grains of H4350. I guess I should load up 3 rounds each of 41.2, 41.4, 41.6 , 41.8 , and 42gr for round two. HOWEVER, the thought of a 2775fps node from a 22" gas gun is both intriguing and scary at the same time. Should I even look for a high node around 43grains or is that just too high? Looks like the Hornady 140eldm's might show more promise on the high side than the Bergers. the Bergers made a nice grouping at 42.8 - 43.2gr, but thats not a very wide powder range.

 

[jwolf]

Are these velocities measured at 100 yds? I have an Ar10 in .260 Rem and I can get no where near those velocities and I measure at 10 ft. I have bad swipes and pressure signs way before that. Also is it normal practice to tune with the gas off? Asking because I've only been loading for gas guns for a while and know nothing about it albeit I've been reloading bolt guns and pistols for 40 plus years. My Armalite is wrecking brass. Have added adjustable gas but haven't had much luck in changing anything. I to am reloading H4350 and am about to think it may be a tad slow for a gas gun.

 

[padom]

yea thats hot for a 22" semi and those primers look flat. My 22" Rock Cut Rifled 6.5cm semi is shooting 140 ELD's with 42.2g H4350 at 2730.

 

[jwolf]

My gun is 24" and I can't get anywhere near that fps measured at 10 ft if I want to use the brass again. I would think that shutting the gas off would aggrevate the pressure issues. I've never heard of shutting the gas off to test, as turning it back on would change everything. I must be not understanding something right or did no one reply back when this was posted for a reason?

 

[jwolf]

Correction my gun is also 22". Shooting 140gr Amax in new Rem. brass, BR primer with 40.5 H4350 I get avg. 2565 fps Es 19 fps I'm seeing swipes. No primer flattening. Tried playing with gas adjustment but couldn't really tell any difference. In comparision my LRP with a 26" tube same load in lapua brass make 2717 fps and I load it up to 41.5 grs. @ 2782 fps before I get just the slightest increased bolt lift. Both guns are 1 in 8 twist again fps is measured at 10 ft.

 

[Niles Coyote]

Same barrel and Gas length JP barrel, 41.3 (H4350 under a 140 ELD in Hornady brass) is the middle of my node. When new is was running it at 2710, now with 700 rounds through it I an down in the 2670 area. When I tried running the hotter node it lead to more trouble than it was worth...

 

[lennyo3034]

That is way hot for a gas gun. My 24" barrel pushes them at 2720 with 41.2 grains of H4350. I started to see cycling issues and pressure signs at 42.0.