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Disregarded9-side
09-15-2011, 17:40
My load is:
Once fired LC/WC 5.56 brass (left uncut, once fired)
LC 55gr FMJ projectiles
#41 primers
H335 power
COAL @ 2.2150"

So I've been working up a load for this bullet, all was well with ~100 rounds downrange loaded with 22.8-23.6grs. of H335 when I went to try out my max/target load for this project, which was 25grs H335. Some sources/manuals show a max load as high as 26.5grs.

All specs on these rounds are the exact same, except that I used exclusively Winchester brass for the 25grs.

At the range, I warmed up the rifle with 3 of the 25gr rounds having fired the lesser 23.6s before. All three chambered fired, cycled and ejected perfectly.

I then fired ~50ish rounds of the 23.6gr rounds, which also all worked perfectly and in a consistent manner.

When I went back and fired 8 more of the 25grs, none of them ejected or allowed the next round to feed. The BCG would have to be locked to the rear and the magazine removed (but never ripped, as there was never a half chambered live round). Most often the live round would be jammed against the feed ramps, and the spent casing, ruined, jammed by the bolt above the barrel in the chamber.
...should have taken pictures :/

The rifle has a M4 feed style 16" barrel with a 1:9 twist and carbine length DI operation, fed from the same problem free Magpul mags. It has a commercial spec buffer tube and spring that I feel are the only low quality area of the rifle, save for the 'blue' rifle extractor spring where it should have a carbine one.

I do a lot of handgun reloading, but this is only my forth project for my rifle.
Thanks much for any advice. D.

steve4102
09-15-2011, 20:35
If you are asking if your 25gr of 335 with 55gr bullets is to hot, duno, but I doubt it. What did the fired brass look like? After the jamming incident did you try any of the 23.6gr rounds, did they fire and function?

PCJim
09-15-2011, 22:03
I'd bet that your BCG was dry, very dry. ARs like to run wet. Spray it down real good with some Rem oil and I'll bet your problem gets cured.

Other potential reasons... I did note that Hodgdon lists 25.3gr as a max charge for a 55gr variant in both their online data as well on their one pound cans of H335.

The LC brass is probably 5.56 Nato where the Winchester is probably .223 commercial brass. The LC brass, being of military spec, will have somewhat less case volume and will generate more pressure for the same charge/COL. Otherwise, check your remaining unfired 25gr rounds for consistent COL, then pull a couple to recheck the charges. Could be that you mixed up the charges?

While it could be a gas timing issue, that seems unlikely if the lighter charged ammo ran the rifle just fine. This would seem more plausible if you had mixed up the charges and were firing the 25gr charges as the lighter charges, and the 23.6gr charges thinking that they were the 25gr charges.

I still think the BCG was too dry. :dunno:

Boxerglocker
09-15-2011, 23:03
I still think the BCG was too dry. :dunno:

:agree: I run my 55g TAC rifle loads through my DD M4 in rifle matches 60-80 rounds stages fast as I can. Keeping the BCG wet is a must. I prefer CLP and wipe it down prior to every match and thereafter.

wanderinwalker
09-16-2011, 19:31
I can't give advice about that particular malfunction, but I DO highly doubt your loads are "too hot to function". AR-15s will take some pretty stout loads and function well with them without indigestion. (Trust me, I shoot NRA Highpower where heavy doses of Varget and Reloder 15 throwing 69-80gr .223 bullets are normal...)

Did you attempt to fire any more rounds after your malfunction with any other ammo? I know the only load-development issues I've ever had were when I tried to run my AR lubed with a lighter oil (Rem Oil). I picked up some CLP right after and haven't had that issue since.

RustyFN
09-16-2011, 19:49
:agree: I run my 55g TAC rifle loads through my DD M4 in rifle matches 60-80 rounds stages fast as I can. Keeping the BCG wet is a must. I prefer CLP and wipe it down prior to every match and thereafter.

I use CLP on my BCG also, good stuff.

I shoot 55 grain FMJ-BT's with 25 grains of H-335 and they are not too hot.

Steve in PA
09-16-2011, 21:57
Nothing wrong with that load. I have shot literally thousands upon thousands of handload using mixed brass (to include Winchester), 55gr FMJ bullets and 25.0gr of H335.

Its not the load, the issue is with your rifle.

Disregarded9-side
09-17-2011, 01:35
What did the fired brass look like? After the jamming incident did you try any of the 23.6gr rounds, did they fire and function?

The primers and brass showed no signs of excessive pressure, and looked the same as the 23.6gr rounds.
I did shoot at least twenty more 23.6s after and in between 8-9 successive total failures with the 25s.

Its not the load, the issue is with your rifle.

Could a weak recoil buffer spring and/or an out of spec buffer tube be too weak, thusly holding the buffer and BCG back too long?
Extractor/spring issues?
My rifle eats everything with an appetite, loves M193.

PC: Really appreciate your reply. The Winchester brass is advertised to be to 5.56 specs. My COAL is consistent with the other loads.
I think you're all on to something when saying my BCG may have been too dry. While it's not bone dry or anything, I did lube it a little less than normal for some reason (intentionally). I just pulled it out and it's pretty dern dry, especially in places where it counts. This would account for the first three rounds functioning normally, and then the light lube dispersing...though I did shoot OTHER loads (23.6gr) through after and between without issue....

Either way, I'll lube her up real well and try to get out there tomorrow. Thanks to everyone for your replies,
Happy weekend.

Disregarded9-side
10-02-2011, 23:29
The rifle went through a good 30 or so of the 25gr H335s as well as another load today; I made sure it was as wet as an AR should be. I think y'all were right when saying it was simply too dry before--it was very dry when I cleaned it after that range sess.

So all is well with the world, and I deem this thread successful...thanks for pointing to the most obvious solution. As a shooter without too many shooting buddies it means more. Probably saved me money. Cheers.
D.

Boxerglocker
10-02-2011, 23:43
Good to hear that a resolution to you problem was uncovered.

PCJim
10-03-2011, 20:16
Good to hear that a resolution to you problem was uncovered.

Me too!