AR and H4198


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ole farmerbuck
February 2, 2010, 08:52 PM
Anybody else using this powder for their AR? It's the most accurate of all of my powders but it wont cycle. Dont know why, i'm using up to and uncluding 22.5 grains. The cases that do eject are not going very far from me. Talking about accutate though, it is! 26.0 grains of H335, 27 or so of BLC-2 and everything else ejects fine. Any suggestions? More powder?

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Runningman
February 2, 2010, 09:14 PM
Don't know what bullet weight you are using but H4198 is to fast of burning powder for a gas operated ar-15. Its pressure curve is to fast. Hence it is not cycling correctly.

guntech59
February 2, 2010, 09:15 PM
Is your carrier key loose or your gas tube leaking?

The loads you tried should make it function well.

five.five-six
February 2, 2010, 09:17 PM
^ yes, could be not enough dwell time, what sized gas system is your AR? there is only so much time after the bullet passes the gas block and before it is out the muzzle for the gas to operate the action

ole farmerbuck
February 2, 2010, 09:28 PM
Don't know what bullet weight you are using but H4198 is to fast of burning powder for a gas operated ar-15. Its pressure curve is to fast. Hence it is not cycling correctly.
40 grain v-max.

ole farmerbuck
February 2, 2010, 09:29 PM
Is your carrier key loose or your gas tube leaking?

The loads you tried should make it function well.
All of the loads except for the 4198 wotk great.

ole farmerbuck
February 2, 2010, 09:31 PM
^ yes, could be not enough dwell time, what sized gas system is your AR? there is only so much time after the bullet passes the gas block and before it is out the muzzle for the gas to operate the action
I have no idea. Its whatever comes on a Bushmaster. I dont know much about these things.

ole farmerbuck
February 2, 2010, 09:39 PM
Every time i had to cycle it manualy, the bullet that was suppose to go in next had a discoloration to it. Just the bullet not the case. Like i said, all other powders work fine and none of them are max. By looking at Hodgdons site, it looks like it should be throwing the brass out good.

guntech59
February 2, 2010, 09:42 PM
All of the loads except for the 4198 wotk great.
I will defer to the more experienced guys then.

I wonder why Sierra would include this load in the #5 book (for 55gr bullets) if it wouldn't cycle the rifle.

Just rechecked the book....Sierra lists a load for IMR4198 not H4198.

That could be the problem.

five.five-six
February 2, 2010, 09:50 PM
20"A2? then it is rifle length gas system,

did you start off at 20.5 grains or just go straight to 22.5? lots of times max load in a bolt gun is too much for a gas gun

ole farmerbuck
February 2, 2010, 10:01 PM
I started at 21.5 and none would work. Went to 22.5 and a few worked but didnt throw the brass very good at all.

Hodgdon lists the H4198 and it has it on the can too. I can see no reason for it not working.

Bass Ackwardz
February 3, 2010, 12:33 AM
I'm not a big fan of H4198, but I use IMR4198 with great success. My AR eats them all day long.


Bass

ole farmerbuck
February 3, 2010, 05:36 AM
I'm not a big fan of H4198, but I use IMR4198 with great success. My AR eats them all day long.


Bass
But have you actually used H4198 in your AR? If so, would it eject? It sure looks to me like the loads should be plenty hot enough. I'd sure like to get this figured out since it was quite accurate. I'll call Hodgdons today and get their view.

243winxb
February 3, 2010, 07:06 AM
My Guess is 1. Measure the neck of a fired case. Has the neck expanded to its full normal diameter? If the neck has Not expanded fully, you have a low pressure condition. This is caused by light bullet pull because of bullet design? The full diameter bearing surface of the bullet is to short or the bullet is seated to long?? 2. The gas port , the hole drilled into the barrel, might not be at the best location or be the correct diameter for the lite bullets. I know on M16A1's the carbine compared to the rifle have much different gas port size and location. IMR 4198 runs fine in my 3 different auto with Sierra 50 or 55gr bullets. I do NOT like any of H's copies of the IMR's. There was another poster on here using IMR 4198, same problem, very strange. Just a guess.

ole farmerbuck
February 3, 2010, 07:45 AM
Thanks 243. All testing yesterday was with 40g bullets. All seated to about 2.250. Like i said, all other powders functioned fine. This was the most accurate so thats why it bothers me as to why it wont work. I'll measure a fired case today.

ole farmerbuck
February 3, 2010, 07:49 AM
Would using the Lee fcd help a little in pressure? According to Hodgdons, it should have plenty the way it is.

243winxb
February 3, 2010, 11:07 AM
The gas port pressure curve is a critical part of internal ballistics for cartridges used in gas operated firearms. Gas operated weapons are generally tailored to a narrow range of powder burning rates and characteristics. If the port pressure is too low the weapon will fail to function and if to high the weapon may function too forcefully or rapidly causing extraction or cycling problems. When using the fast H4198, the pressure peaks very fast and is done producing pressure sooner than your slow powders. With such a wide range of bullet weights from 40gr to 80gr, matching the gas port location and size is critical. If the gas port was moved closer to the chamber and drilled larger, H4198 would work. http://www.6mmbr.com/223Rem.html

ole farmerbuck
February 3, 2010, 11:18 AM
Ok. If i used regular sr primers instead of the cci #41's, would that help or should i just forget about it?

Walkalong
February 3, 2010, 11:27 AM
Primer isn't going to make the difference.

243winxb
February 3, 2010, 11:41 AM
should i just forget about it? Might be best. Going up in the powder charge might help, but your already at or near maximum, but maybe not for the 40gr Hornady??

rcmodel
February 3, 2010, 12:11 PM
22.5 is MAX according to Hodgdon.

I agree.

H or IMR 4198 is too fast burning to provide the correct gas port pressure with light bullets in some guns.

4198 was at it's best in the smaller capacity .222 Rem in bolt-action rifles.

It is not an ideal .223 powder with any bullet weight.

rc

ole farmerbuck
February 3, 2010, 01:29 PM
Yea you guys are probably right. I was sure hoping for a different answer since this stuff is so accurate. I'm not having the best of luck with h335. I have a good variety so i guess i'll move on.:mad:

five.five-six
February 3, 2010, 03:23 PM
Ok. If i used regular sr primers instead of the cci #41's, would that help or should i just forget about it?
Primer isn't going to make the difference.

in my ar's regular primers = slamfire every so often

Walkalong
February 3, 2010, 03:27 PM
Very good point. My point was they would not fix his problem. :)

critter
February 3, 2010, 05:44 PM
I use the same load in my super 14" Contender. I fully agree on the accuracy! It will do 3/8" at 100 yds in my TC. Good luck with your AR. Seems as if it should work.

five.five-six
February 3, 2010, 08:04 PM
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 ;)

shootinblanks
February 3, 2010, 09:33 PM
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:

ole farmerbuck
February 3, 2010, 10:11 PM
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.

ole farmerbuck
February 3, 2010, 10:12 PM
Rl 10x is working out pretty good too. I might try some rl 15 since i have it.

five.five-six
February 4, 2010, 07:41 PM
ok, rem 7 1/2's don't slamfire in your rifle... cci 400s do in 2 of mine..YMMV

counterclockwise
February 5, 2010, 02:57 PM
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.

GooseGestapo
February 5, 2010, 09:14 PM
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!

ole farmerbuck
February 5, 2010, 09:41 PM
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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