Finally "Broke" an AR

[Clint]

Dropping to an A5H0 should help, but may not be enough to make it fully reliable.

We'd probably still touch up the port to 093 to avoid any future issues.

The rifle started life with a 20" barrel, hence the A5H2 buffer. I swapped it for an 18" with a new bcg some time ago, and round count has been pretty low on it since then.

Should I drop back to an A5H0 or H1 first? I have a plethora of steel weights on hand.

Andy

[hotbiggun42]

My first AR was a oly arms car15 bought it in 1994. Shot about 1000rds through it in one day until it began having failure to feed and extraction issues. I had no idea i needed to oil the bcg.
Went back to shooting my Mak 90s.

[AndyLate]

To continue beating the dead horse, this rifle functioned normally when oiled with all (brass case) factory .223 and 5.56 I tried, plus some mild-ish reloads. Functioned normally meaning ejection direction and distance similar to my 16" mid and optimum gassed ARs, last round bolt hold open, etc.

When I took it to the range without lube after a thorough cleaning, it functioned normally until I changed to some Hornady 55 gr soft point 223 and the bolt consistently failed to return to battery with a live round about 1/2 out of the magazine.

I messed around for a couple rounds, tried a different magazine with no change, then swapped to another gun. The second rifle fired the remaining 10 rounds or so of that ammunition without issue.

Maybe the ammo was a little weak, I don't know. I do know that I will put an oil bottle back in my range bag.

Andy

[vicious_cb]

To continue beating the dead horse, this rifle functioned normally when oiled with all (brass case) factory .223 and 5.56 I tried, plus some mild-ish reloads. Functioned normally meaning ejection direction and distance similar to my 16" mid and optimum gassed ARs, last round bolt hold open, etc.

When I took it to the range without lube after a thorough cleaning, it functioned normally until I changed to some Hornady 55 gr soft point 223 and the bolt consistently failed to return to battery with a live round about 1/2 out of the magazine.

I messed around for a couple rounds, tried a different magazine with no change, then swapped to another gun. The second rifle fired the remaining 10 rounds or so of that ammunition without issue.

Maybe the ammo was a little weak, I don't know. I do know that I will put an oil bottle back in my range bag.

Andy

Congrats you've inadvertently found the sweet spot that race gunners are constantly tuning their guns for, the ragged edge of functionality and softness. Now you can go out, put on a silky shirt and shoot a dozen A-zones at 3 yards really fast.

[AndyLate]

Congrats you've inadvertently found the sweet spot that race gunners are constantly tuning their guns for, the ragged edge of functionality and softness. Now you can go out, put on a silky shirt and shoot a dozen A-zones at 3 yards really fast.

I can't even shoot fast at 3 yards tho.

Andy

[Todd.K]

Maybe the ammo was a little weak, I don't know. I do know that I will put an oil bottle back in my range bag.

One interesting thing with longer gas systems and less dwell time is that “weak” cycling ammo doesn’t always mean lower velocity. Powder burn rate affects pressure at a rifle gas port that you would never notice in a carbine.

[BufordTJustice]

One interesting thing with longer gas systems and less dwell time is that “weak” cycling ammo doesn’t always mean lower velocity. Powder burn rate affects pressure at a rifle gas port that you would never notice in a carbine.

That is actually very interesting. Can you elaborate?


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[Todd.K]

Sure, M855 military ammo has a gas port pressure requirement that I’ve seen, they do that to ensure function.

PMC used the wrong powder in their Bronze M193 back in 2000 something. Ran fine in carbines, choked hard in rifles.
https://www.m4carbine.net/showthread...C-ammo-problem

Hornady Superformance is basically the opposite. Look at the pressure curve chart they have where the pressure goes up faster, a regular faster powder would also go up faster but then drop off faster after the peak. So it could have similar velocity (area under the curve) as the standard load but lower pressure at port.
https://www.hornady.com/support/supe...rated-firearms

[BufordTJustice]

Sure, M855 military ammo has a gas port pressure requirement that I’ve seen, they do that to ensure function.

PMC used the wrong powder in their Bronze M193 back in 2000 something. Ran fine in carbines, choked hard in rifles.
https://www.m4carbine.net/showthread...C-ammo-problem

Hornady Superformance is basically the opposite. Look at the pressure curve chart they have where the pressure goes up faster, a regular faster powder would also go up faster but then drop off faster after the peak. So it could have similar velocity (area under the curve) as the standard load but lower pressure at port.
https://www.hornady.com/support/supe...rated-firearms

Understood. Thank you.

I've used Superformance for several years now (55gr 5.56 GMX) in my 16" intermediate and 11.5" suppressed SBR. Idefinitely moved up one buffer weight compared to nato pressure 55gr.

Pressure under the curve. Interesting.


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