AA40 Frangible

[psalms144.1]

I just finished instructing day 1 of a 3 day rifle course to certify five other agents to carry M4s on duty. The POI went VERY slowly, because all five rifles were experiencing MULTITUDES of failures with this ammo. Most typically, the rifles are failing to feed with the rounds getting caught up 1/3-1/2 way into the chamber.

I'm beyond frustrated, as are my students, who are literally spending more time clearing feedway jams than shooting at this point. Of six rifles, one (a lightly used Colt M4A1) literally will not shoot two rounds in a row with this ammo. Four of the others are malfunctioning regularly. So far, only one rifle has avoided the curse. Four of the six rifles (including the one outlier that's working) are brand new out of the box FNs. All were stripped, cleaned, and lubed prior to starting shooting.

My immediate thought is, get new ammo (duh!). Unfortunately, this is the ONLY training ammo we have available, and we don't have anywhere near enough duty ammo on hand to meet the round count requirements (about another 1,000 rounds/shooter) for the rest of the course.

Having said all that, anyone have any luck getting this crap to run in M4s? If so, any advice?

Thanks!

[Lomshek]

I just finished instructing day 1 of a 3 day rifle course to certify five other agents to carry M4s on duty. The POI went VERY slowly, because all five rifles were experiencing MULTITUDES of failures with this ammo. Most typically, the rifles are failing to feed with the rounds getting caught up 1/3-1/2 way into the chamber.

I'm beyond frustrated, as are my students, who are literally spending more time clearing feedway jams than shooting at this point. Of six rifles, one (a lightly used Colt M4A1) literally will not shoot two rounds in a row with this ammo. Four of the others are malfunctioning regularly. So far, only one rifle has avoided the curse. Four of the six rifles (including the one outlier that's working) are brand new out of the box FNs. All were stripped, cleaned, and lubed prior to starting shooting.

My immediate thought is, get new ammo (duh!). Unfortunately, this is the ONLY training ammo we have available, and we don't have anywhere near enough duty ammo on hand to meet the round count requirements (about another 1,000 rounds/shooter) for the rest of the course.

Having said all that, anyone have any luck getting this crap to run in M4s? If so, any advice?

Thanks!

@psalms144.1

Maybe I can offer some ideas before lunch ends for you.

If the ammo meets dimensional spec (not something goofy like an out of spec case rim) then it may be over or under powered ammo affecting carrier velocity or travel.

Since these are almost all brand new rifles (and mags too perhaps) I'd test them with some known good ammo just in case first.

If you have a phone that'll do slow motion video filming the extraction and feeding cycle may help you to see what's happening. Have someone else shine a light into the ejection port and try different camera angles to see what's going on. Lacking that the difference in extraction between a known good load and your training ammo will tell you pretty quick if it's weak as weak ammo tends to just dribble out and good ammo get's chucked at least a few feet.

If the ammo is underpowered and failing to move the BCG all the way to the rear you can remove the weights from the buffers to create a super light buffer. I did that for a rifle when I was firing craptastic Wolf steel junk and it turned a short stroking rifle reliable.

All you need is a pin punch and maybe some pliers to pull the buffer bumper and out they go. Keep the weights organized by rifle in baggies or something!

If you go that route don't forget to replace the weights at the end of class!

[ST911]

What lot number?

That ammo is common DOD training round and should be cycling M4s in spec without issue. It isn't awesome ammo, but it works well enough.

Isolate variables and follow the bread crumbs, but I suspect you already have. Try your ammo, new ammo, your mags, different mags, recombine uppers and lowers, etc.

[psalms144.1]

@Lomshek - thanks, unfortunately any modifications to the rifles is a no go since they're .gov issued weapons.

@ST911 - lot number was WCC10F028004

Final count was six guns on the line. Two worked with the ammo flawlessly. Two had intermittent problems, but we could keep them limping along with frequent stops to clean and relube. Two were completely useless with the AA40 - one would literally not shoot more than 2 rounds without a malfunction.

The ammo is clearly VERY underpowered. Switching to AB49 ammo got both of the "broken" rifles working 100%. Unfortunately, that meant we had to burn up about 800 rounds of our VERY limited stash of AB49 in order to get two shooters through the last four hours of range time. If I wasn't running the course in NJ, I'd have run to the nearest gun store of big box and just bought 1,000 rounds of basic 5.56 ball and put in a voucher hoping for reimbursement...