Alright, so had my first real baffle strike today and trying to diagnose so I can prevent it from happening again.  Happened with my just out of jail Aero Lahar-30K on a 300BLK Sig Rattler utilizing Plan A.

Happened about 150rds into the shooting session. I’d checked the suppressor a few times at earlier round counts and didn’t notice any signs of a bullet striking the baffles at that point.  Around the 150rd mark, I was shooting at silhouettes at the 100y line and noticed my shot impact the ground only about 25y from my firing position.

Stopped what I was doing, pulled the can, and was greeted with a pile of what looked like crumbled lead and jacket material.

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So I’m at a bit of a loss.  Alignment seemed to check out via my eyeball.  I also checked alignment with a rod and it looked fine, so I’m thinking it’s not an alignment issue.  The Rattler with such a short barrel got me thinking that stability might be an issue, but I was shooting 125gr supers, so I’d think the 1:5 twist should have no problem with stabilization.  Could it be the ammo?  1:5 twist is pretty fast, so could the projectile have shred its jacket immediately upon exiting the muzzle?

With the amount of material in the can, I’m thinking there’s no way an intact projectile contacted the blast baffle with the minimal damage I’m seeing, so in my head that leaves only the ammo.  

Blast baffle.  Impact marks in two spots opposite each other.  The impacts deformed the baffle material enough that the bore is no longer perfectly round.  The one marked with an X is the more severe side.

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Looks like something hit the last baffle in the clip cutout, causing some deformation and a small crack.

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Also looks like the muzzle cap took hits from a bunch of fragments.  The worst spot is directly opposite the largest mark in the blast baffle.

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Thoughts?

I don’t see how an intact projectile yawing so badly it strikes opposite edges of the blast baffle would cause such light damage, which has me leaning towards an ammo/projectile fragmenting issue.  Is it typical to see so much projectile material in the can after a bore alignment related baffle strike?

What brand ammo?
Here is a thread where someone had a similar problem

https://www.ar15.com/forums/AR-15/-ARCHIVED-THREAD-7-5-300BLK-1-5-twist-yay-or-nay-/121-773024/?page=2

The Rattler barrels are so short, minus the chamber length, leaves much less actual rifled length left. I've read, one wants a rifled length to at least equal the twist, so 5" of rifled length for 1:5 for stability. That said, no personal experience, so hopefully, others can clarify, confirm, or expound upon this.

AAC (PSA) 125gr

Were your bullet holes perfectly round on your target?

You could always try shooting into a sand or dirt mound and recovering the bullet to see if your jacket is shedding. I believe stacking a few water jugs behind each other would work too

Its an (extremely) old wives’ tale from what I can find. Rate, not length, seems to be the thing that matters for imparting the desired RPM, in combination with velocity. Its kind of like saying a round travels at 2,200 feet per second*. It doesn’t have to travel 2,200 feet to accelerate to that. For rifled length to meaningfully impact RPM, the bullets would have to be skidding across the rifling, and I’ve never seen proper ammo show evidence of that on recovered jacketed projectiles. Keep in mind that the bullet isn’t hitting the rifling at 2,200 fps….It is only beginning to accelerate.

1:5 spinning supers apart is a hot debate, and this thread might be proof that it can be a problem. Might be a fun experiment to launch a few mags at close paper without the can.

Edit: *Randomly chosen number

That thread was me with all the problems of jackets shredding etc. My symptoms look just like the OP’s. The 1/5 is spinning the bullets apart.

Looks like it spun apart. Was the barrel particularly hot? Supposedly that can exacerbate the issue. A bullet coming out of a 1-5 twist barrel at around 2000fps is spinning as fast as a bullet coming out of a 1-10 twist at about 4000fps.

I was shooting at steel when this occurred, so unknown.

The first 30ish rounds of the day were spent zeroing at 50y on a paper target and those all looked fine.  That was also using Barnes 110gr for all but the first few sighters.

I may need to try this thing out on paper without the can using the AAC ammo.

I may have to try that to see if I can get some confirmation.

Yeah, it was fairly hot.  It was at the end of a few mags shooting offhand from different positions/barricades, so figure 70-80 rounds in a few minutes.

Not going to be able to do it for a couple weeks, but I’ll do some close range paper tests to see if the bullets are shredding at the muzzle.

My hunch was bullet spun apart.  Someone check my math here.

1:5 twist, bullet makes 1 rev every 5in.
2000fps velocity is 24,000 in/sec
24000/5 = 4800 revs/sec

That bullet is really spinning at 288,000 rpm??

There’s a blog called 196,000 Revolutions Per Minute that used to write some neat stuff there, and on TFB back when more articles were a real read. I don’t think they’ve written in the linked blog in 8 years, but I do remember the first time I read about RPMs and thought it was such a freaking wild number.

Your math is right, but I seriously doubt a 125gr bullet is hitting 2000fps out of a 5.5" barrel without seeing popped primers/bulged cases.

I didn’t chrono any of the 125gr out of the Rattler, but Barnes 110gr is averaging about 1925fps out of this gun.  If I had to swag, I’d say 1750-1800fps.

There were a couple major errors in my post that you quoted, that I just fixed. I think you understand what I meant, but I didn’t want to put out bad info.

Good to know, thank you. FWIW, I *think* it was have been Garin (Kudu22) from Surefire in reference to why they opened the bore of the Socom SB and why one should choose it over the RC for sub 10" barrels. Less than 10 inches minus the chamber leaving possibly less rifled barrel than the twist rate.

If the full rotation rule were true, pistols would never stabilize bullets.

Yeah, I was tracking what you were trying to put down.

Stop shooting aac/psa through your cans. It's been documented enough times that aac/psa ammo is not really jiving with cans.

You spent a lot of money on your rattler and your can. Up your ammo game. If you need to shoot stuff without a can and confirm, do it. Just stop buying that junk.

The worst part is I've read psa will not help you with your suppressor warranty if you shoot aac ammo through it.

Do you have any links to these issues?

Not doubting, I just like reading through things myself.  I was an early adopter with this ammo and it’s far from the only 300BLK ammo I have, so if I have to move on it’s not the end of the world.

That said, if this is an RPM issue, I’m potentially going to have issues with cheap jacketed projectiles regardless of who manufactured them.  I need to figure that question out without jumping on the “PSA BAD” bandwagon, otherwise I’m just going to end up right back here with a different manufacturer’s ammo.

From what I can figure out, it seems copper solids don’t have the same issues, so I’m good with my Barnes defensive loads there.  I’m not shooting $1/rd+ premium ammo for training, though, so if I need to step up to a heavier super load, decreasing velocity (and as a byproduct, RPMs) may be something I have to explore.

My local PSA has a rental range. The shelves in the store have AAC ammo. The rental range does not…….

Though, it sounds like a twist problem, of the type usually involving .22-250 or similar.

There's a guy on reddit that tracks fucked up suppressors. This is 6 months old.

https://www.reddit.com/r/NFA/comments/16cyhe0/aac_77g_through_suppressor/

Google also pops up some stuff:
https://www.google.com/search?ie=UTF-8&client=ms-android-att-us-rvc3&source=android-browser&q=aac+jacket+ammo+suppressor

This has been a known issue for a while, unfortunately. Since psa doesn't want to seem to help anyone or fix the problem, I don't really care what the issue it. It's just garbage ammo to me. I'm sure some dude in a ban state shooting a 16" 1:8 loves it.

Oooof.  None of that is good.  Most all the reports I’m seeing are issues with 55gr .224 projectiles, but I wouldn’t be shocked to see the issue extending to other FMJ projectiles they produce.  It’s enough that I’ll likely relegate this ammo to non-suppressed plinking.

Still going to test it out and see if I can duplicate the issue sans suppressor.  If this shit is blowing up cans like that, it needs to be documented so people can be made aware.

Thankfully I don’t have any other AAC ammo and never really planned on purchasing any.

Now I’ve just got to hope Aero will fix this.  I honestly think it would be fine to continue using, but I’d rather be safe before I have a complete blowout from some defect I can’t see.  Them being new in the suppressor game has me wondering, so I guess we’ll see.

Either way, I’m gonna test it.  I’ll get her hot running a bunch of drills and then fire a bunch of rounds into a cardboard target at varying ranges to see if it’s an instability or jacket separation issue.

The two links I provided earlier show this is well documented. There's literally a guy on reddit who keeps a spread sheet; it's public.

Sorry you're having issues, but don't shoot budget ammo out of a 3 thousand dollar rifle. Keep in mind PSA is still very new to making ammo commercially. It sounds like a lot of you guys are the test dummies and PSA doesn't really care what happens to ya'll.

Consider this a lucky lesson learned. Aero will fix this for you.

This right here tell us everything we need to know about their ammo.

Good enough to sell to consumers, but not good enough for their rentals?

Yeah, I thought it strange, considering every time I look at the shelves the AAC is (artificially or not) priced, well, competitively. Maybe the profit margin is better if they send it out the door instead of downrange. I’d be open to an explanation, but it seems strange.

I can't get it through distribution (just like all their other psa stuff).

Cut out the middle man (distro), and you get more freedoms with your margin. I'm glad that psa is making ammo that is more budget friendly, but put some sort of disclaimer about suppressed shooting.

It’s not a “budget ammo” issue.  There’s plenty of FMJ loads out there that fall into the same price range that don’t do shit like this.  I highly doubt your plinking loads are all $1+/round premium ammo, so attitudes like that give false impressions to those newer to this realm.  I’ve got tens of thousands of rounds of “budget” ball ammo through a bunch of different high dollar guns (with cans) without a single issue.  I’ve shot a couple thousand S&B FMJ .300BLK loads through suppressed high end guns with nary an issue and both AAC and S&B can be found for essentially the same price per round.

ETA:  Just to clarify, I’m not advocating shady “reloaded” ammo manufacturers or anything of the like (FM, etc).  I’m talking about other factory new ammo in the same price range.  Federal, LC/Winchester, S&B, Fiocchi, PMC, etc.

I’ll also add, this issue could have more to do with the rifle setup than the specific ammo manufacturer.  Others have reported similar issues out of 1:5 twist barrels with ammo that isn’t from PSA, so while it may be easy to point the finger at the ammo, there doesn’t appear to be much specific evidence suggesting one or the other in my case.  Further testing will hopefully shed some light on this.

As an aside, the posts about AAC ammo are certainly concerning, so I’m not trying to outright dismiss what you’re saying.  Enough that I’m not going to shoot any more through my suppressed guns and I’m not going to be buying any more unless something publicly changes significantly.  Trying to remove reports of ammo failures looks 10x worse than just letting threads like that run their course and addressing the issues publicly.

Here are three more links I found. I don't know about you, but the 5 links I provided are enough to not recommend this to my customers.

https://www.reddit.com/r/NFA/comments/15e0740/psa_aac_300bo_jacket_separation/

https://www.reddit.com/r/300BLK/comments/18qr6t8/jacket_squib_from_psaaac_125gr/

https://palmettostatearmory.com/forum/t/aac-208gr-a-max-300-blk-problems/22052


7 mos ago, 2 mos ago, 15 mos ago; respectively.

What other commercially available loads are tearing up 1:5 guns? I haven't heard of any recently.

There’s a link near the top of this thread with the OP posting just below about different projectiles having similar issues.  It’s a bit hard to follow with no usernames, TBH.  Appears to only be in relation to heavy subs, so maybe not the best example.

The other reports I found yesterday may or may not be recent, didn’t really look at the dates.  

Bottom line, I want to make sure this is an ammo issue.  At this point, it may very well be this specific ammo.  It may even be likely.  I still want to make sure that’s the case before I send another frag’d projectile into a can because I didn’t do my due diligence.  I’ve got other light supersonic factory loads that I can run through the gun side by side and compare, so it’ll be easy enough to sort out.

If it is the ammo, sounds like I’m going to have a fun time getting a refund.  Yippee.

I think the ammo is just generally suspect. I also think that its simply the lightest-jacket super you’ve shot thus far. Do you also have any varmint bullet supers of similar or greater expected velocity to shoot alongside? This isn’t the first time I’ve heard of problems with very fast twists that appear to be designed to accommodate solid copper* subs. One of the manufacturers of said ammo happens to recommend barrels of such twist.

*in case you’re not a nerd: copper is less dense than lead, so similar weight projectiles are longer. Longer (rather than simply heavier) bullets require faster twists.

I’ve got some factory 110 VMAX as well as some other FMJ, so I’ll test it out and see.

I don’t have a ton of rounds down range with 5 twist barrels, so this is certainly newer territory for me.  If this is looking like an issue across the board, I’ll have to look into heavier super projectiles to bring velocities down or just ditch the MCXs altogether since they’re stuck with that twist.  A gun that I can’t economically train with is useless to me.

110 VMax is exactly what popped into my head, along with a couple others, as most likely to be demonstrative.

Could be a liability thing. If it is your rental gun and you manufactured that ammo, and something blows up and hurts somebody, pretty hard to say you're not the one to blame.

I recently bought some of that AAC 300 BO subs to try out. After reading this now l don't know if l want to. Had no idea their ammo was causing issues.

Subs are twisting roughly half the rotational speed that supers are. So, this particular issue may not be a problem for subs. Of course, that doesn’t eliminate other ammo related problems that could be present.

I've occasionally heard of expanding subs opening up inside the suppressor when fired from ultra-fast barrels, but I've never heard of a sub spinning itself apart.

New thread here:  https://www.ar15.com/forums/ar-15/Don-t-shoot-PSA-AAC-300BLK-125gr-FMJ-supers-through-your-can-/16-785995/?page=1

Bottom line, it was the ammo.

color me shocked. glad you got it figured it out.

Do you have a 1:7 or 1:8 twist blackout to test the same ammo through?  I’m wondering if the ammo problem is jacket thickness not being able to handle the 1:5 twist.

Not at the moment.  I’ve got a barrel off being cut down, so I will in a few weeks.

They’ve since added some boxes at the rental counter.