AR and H4198

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My point was they would not fix his problem

yes. I understood that, just pointing out one more reason not to switch off 41s..... then again slamfires are fun....if I just knew when they were going to happen ;)
 
I have been reloading Rem 7 1/2 s and haven't had a slamm fire in 1000+. Ole farmer, BL-C2 has been a pretty decent powder in the DPMS AR, and of course Varget. I ll keep listening in on your questions, still learning:banghead:
 
I have been reloading Rem 7 1/2 s and haven't had a slamm fire in 1000+. Ole farmer, BL-C2 has been a pretty decent powder in the DPMS AR, and of course Varget. I ll keep listening in on your questions, still learning:banghead:
Yea i get pretty nice groups with blc-2. I have a lot of Varget and have only loaded a few loads with it and wasnt impressed. Its not like i tried working up a load though. Maybe i might spend a little time with it.
 
I ran some QuickLoad studies on the 40gn .223 situation. To mimic the pressure profile of say 55gn M193 load which runs the AR very well, you would need to stoke up the 40gn load load above SAMMI MAP up toward 60,000 psi chamber press (more like a NATO MAP limit) That would get you about 25,000 psi at the port in a 20" bbl. AR. But, the downside is that the 40 gn is moving faster at the port than the 55 gn for the same bbl length. So, the pressure pulse dwell at the port would be shortened for the 40 gn. More pressure, more speed, less dwell. Less pressure, less speed, more dwell. Maybe there is an auto-loader sweet spot in there somewhere.

As you run the 40 gn faster, you may begin to see a diminished accuracy. That is not unusual. Many handloaders have found that the accuracy sweet spot for a particular configuration is well below max. MAP allowed. Also for fast twist rigs, say 1:7, some those little fast mover boollits can spin apart after they leave the muzzle.
 
The 22.5gr load is too light for the AR. Remember, the throat on an AR is different than the .223 Saami spec chamber. That is what Hodgdon/Imr used to develope the data. It takes a bit more pressure to get the gas system to function. With a 49.5gr cast bullet, it took 19.8gr of IMR4198 to function, and by then the velocity too high for good accuracy.

I found that a 23.0gr load was minimum in my Bushmaster that I had back in the mid '90's. The one I have now with a 16.5"bbl takes 19.8gr. 24.5gr was max.- But, then the 14.5"bbl w/AK style muzzle brake was getting ~3,400fps. Accuracy was as you've seen, excellent.

My guns most favorite load was the 60gr Hornady PtSpt over 21.0gr of IMR4198 for 2,850fps. Killed deer light lightning, too!
 
I had thought about bumping it up another 1/2 grain just to see what happens but didnt. We'll see if the weather ever clears up.
 
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