9mm blow up

[abunaitoo]

Had another 9mm blow up yesterday.
No one got hurt.
9mm AR
Not sure what caused this one.
Most of the time, the primer goes off before chambering.
This one has a firing pin hit to the primer.
Suppose to be factory ammo.
We've had a few of these happen from time to time.
Friend almost died when a tiny piece hit him in the side.
Went to the hospital and it had nicked his spleen.
Has no spleen now. Seems you cannot stitch a spleen.
He's doing fine now.
242136242137242138

[Winger Ed.]

Something is wrong with that weapon,
it looks like it is getting a slam fire when the firing pin isn't retracted, and the bolt isn't closed.

This function is not to be confused with something that is made to fire from and open bolt and has a fixed firing pin.
They have heavy bolts and real strong springs to push it into battery, and are designed to work like that.

Not that something wild would do that in a properly functioning weapon, but what do ya mean, "supposed to be factory" ammo?

[abunaitoo]

I know about slam fire.
Used to happen all the time on my MAS semi auto.
Heavy floating firing pin. Machined some weight off to make it lighter.
Problem solved.
Haven't seen a fixed firing pin rifle, in a semi auto, for a long, long time.
I kind of remember working on one once. Forget what it was, or what caliber.
Never worked on a 9mm AR, so I don't know if it has the same floating firing pin as the .223 AR.
Could be the cause.
Pistol primers have softer cup.
Owner said it was factory. Had a box of factory on the table. It looked like factory ammo. Box was more than half empty.
I didn't ask anymore about the ammo.
Didn't want to make it seem like I didn't believe him.
I always try NOT to make them feel like it's something they did wrong.
Don't want to come off like I know everything.
BUT.........I never assume anything. No matter what is said.
And keep it to myself. Less chance of offending someone I don't know.
Keeps me safe, and out of trouble.
As I said, we've had a few of these happen over the years.
Most are caused by the bolt hitting the primer when feeding.
This one has a clear primer hit. Plus the primer is backed out a little.
Owner didn't know if it chambered, and he pulled the trigger, or not.
All he remembered is it went bang, and jammed.

[Winger Ed.]

Just curious about the ammo. For that event, it wouldn't matter what they were.

Those primers were struck by the firing pin, and those rounds went off before they were fully chambered.
Cases won't look like that if it happened fully chambered without the barrel blowing apart.
Even then, there wouldn't be the bulges, they'd be fully ruptured, or more nearly shattered & shredded.

I'd take it all apart, strip down the bolt too, clean it well, and take a look.
It might just be too dirty for the firing pin to retract like it should

[trapper9260]

The shotgun my dad gave me that is a pump. It would after you shot the first round. Then when you pump it to put another one in the chamber .the 2nd one would at times go off. I was a use to it. But was thinking that if I let someone use it with me and not use to it something bad would go wrong.I had some one fix it. It was a bent spring. Now it is fine no problems. Just to give you a idea about how it happened not only to semi auto .

[Sig556r]

Pics#1 & #3 seem to indicate it wasn't fully chambered when the primer went off, which may mean that it fired while bolt is loading the round.
Good thing no one got hurt.

[skeet1]

Pics#1 & #3 seem to indicate it wasn't fully chambered when the primer went off, which may mean that it fired while bolt is loading the round.
Good thing no one got hurt.

I agree this rifle fired out of battery while the round was being chambered. possibly a stuck firing pin.


Ken

[phonejack]

I would check to see if the firing pin is jammed in the forward position. Either from a factory defect or lack of channel cleaning. It should freely slide in and out by shaking the bolt carrier.

[SSGOldfart]

Was this gun a factory built or homebuilt?

[popper]

OOB firing. Check FP, dirty channel or bent. Possible (not likely with factory ammo) large case. Factory box means nothing. I do NOT put reloads in factory box.

[DCP]

You might want to check the range out!
Be on the lookout for the Menehune.
Lots of strange things going on there.

[edp2k]

A 9 mm AR is a blow back operated gun.
In a 223 AR, which has a separate bolt and bolt carrier, the bolt must rotate sufficiently (in lockup/battery)
to allow the FP to protrude from the bolt face and reach the primer.
The 9 mm AR has a one piece bolt+carrier, and the only thing that keep it from firing out of battery
is how much the rear of the FP extends past the back of the bolt, and how far rearward the bolt can be and still allow the hammer
to touch the rear of the FP.

If the bolt is too far back, the hammer will hit the lower edge of the bolt before it can reach the FP.
With today's put-together-from-parts 9mm ARs, tolerance stack and just plain loose tolerances
can produce a parts tolerance stack up such that the bolt can be significantly (i.e. dangerously) out of battery (i.e. rearward) and
still allow the hammer to reach the FP.

combine the fact that a 9 mm AR is a blow back gun, and thus the chamber gets very cruddy, and people may not use sufficient lube and
then shoot 100's of rounds without cleaning or lubing, you have a recipe for the bolt to not return 100% to battery (forward) when the trigger is pulled.
if you have the aforementioned bad tolerance stack up, you get an out-of-battery firing event. boom.

if the FP is indeed not stuck forward, this is what happened.
One solution is to take 0.010" off the rear of the FP and then put an empty primed case in the chamber, put a small piece of 1/8 inch cardboard
in between the bolt and the breach face, pull the trigger, and see if you can get the primer to go off.
if it does, take off another 0.010" and try again.

[tomme boy]

Just about ALL 9mm AR9's will fire out of battery. Most all new ones are coming with a spring on the firing pin so it will not slam fire.

Find out which extractor it has. Seems to happen more with bolts that have the 1911 style extractor. The newer ones with the ar15 extractor it is not happening no where as often as the 1911. The round gets stuck in front of the extractor and the gun is fired and you get what is exactly shown.

[243winxb]

"A 9 mm AR is a blow back operated gun." As posted above, is the problem.

[Hick]

Brass looks surprisingly grungy to be factory

[flyingmonkey35]

sorry for your friend.

but as a guy who has had two guns blow up on me. I do not take this lightly.

unless you can completely I'd this issue as your fault.

send the gun back to the factory. if it's a custom built rifle send the complete bcg back to the factory.

DO NOT ignore this.

if this was your firearm your friend has a good cause to sue you for medical damages.

factory's can't fix problems if they don't know about them.

Sent from my SM-G960U using Tapatalk

[country gent]

On semi autos the drag of the cartridge coming out of the mag slows cushions the bolts closing. I suspect a heavy buffer spring and light mag drag contributed to this. even a sticky firing pin should reach the firing pin until its in battery. If part of this conversion is a firing pin spring Look at it for collapsed coils or breaks. Look at the firing pins nose for thinness, sharp edges and length. Check pin to be sure its free, straight and not binding.

[jj850]

Just about ALL 9mm AR9's will fire out of battery. Most all new ones are coming with a spring on the firing pin so it will not slam fire.

Find out which extractor it has. Seems to happen more with bolts that have the 1911 style extractor. The newer ones with the ar15 extractor it is not happening no where as often as the 1911. The round gets stuck in front of the extractor and the gun is fired and you get what is exactly shown.

help me if I am thinking about this wrong, but if the round is in front of the extractor how will the firing pin reach it

[abunaitoo]

Didn't know the guy.
Didn't get any information on the rifle.
He did shoot more after, and all was good.
When I went back, he was gone.
I did find some 9mm cases by where he was.
Cases very dirty. Lots of carbon all over.
When my friend got hit, he was over 3 feet away.
Tiny little hole that wouldn't stop bleeding.
He said he felt fine, but another friend took him to the hospital.
Good Thing. Might have saved his life.

[root]

Look like they came out of my lage max 10/31.

Get those every now and then due to it being open bolt slow fire.

That gun in the OP has a issue though.
I agee check the FP and channel.

Rich

[popper]

Original AK had that problem, they put a spring on the FP (US imports) to solve the problem.

[gwpercle]

" Another blow up ".... Time to change something .
Glad you OK but somethings not right .
Gary

[BigAlofPa.]

I find blown out 9mm casings at one of the shooting spots. Wish i could find out who is shooting them. Not sure if he is aware.

[edp2k]

Original AK had that problem, they put a spring on the FP (US imports) to solve the problem.

That is a slam fire, where the bolt locks up and the FP has enough inertia to move forward and fire the primer.
In the cases where this happens typically commercial primers are being used, which are harder than mil primers.
A FP spring can mitigate this problem.
Militaries typically don't want to employ a FP spring as the fore/aft movement of a spring-less FP (imparted by the soldier walking with the gun)
"self cleans" the FP channel and helps prevent FPs rusting/crudding-up in place.

That is very different that the scenario shown in the OPs pics, which definitely fired out-of-battery, thus is not a slam fire.

[Lloyd Smale]

ive got two 9mm ars and ill tell you what I think happened because it happened to me a number of times before I got my 4.5 inch gun worked out. There blow back guns. As soon as the primer ignites the charge the bolt starts back. If you don't have a heavy enough buffer or buffer spring the case can come back to far before the pressure has dropped and it will blow out the base of the case. Cure. run a 308 carbine buffer spring. At least a 5.5 oz buffer and NEVER put a reduced power hammer spring in one because the hammer spring is the first resistance the bolt has in its rearward trip. all three of these cures keep the bolt from coming back prematurely and the heavier buffer spring also helps the bolt come back into battery with more power. I also use a buffer spring cushion that goes on the back side of the buffer spring. It has a couple purposes. One is it keeps the bolt from coming back to far and breaking the bolt hold open if you have a colt mag gun that has a bolt hold open. It also shortens the stroke of your gun and helps the spring push the bolt back with even more speed. Id like to pretend to be the pro that discovered all of this but im not. I talked to a guy that does custom 9mm ars because I was having feeding problems and blown case problems like you. Since then ive put probably 2k threw the gun with a not a single case failure. Another good thing is a feed ramp. The barrel I got with my upper had about no forcing cone and most 9mm ars have no ramp (my cmmg does) . I was told to buy a faxom barrel because they had a more gradual forcing cone. 100 bucks later it didn't look a bit different. then I found where some are putting in a ramp. Its just a small piece that you inlet into your upper. think it cost like 20 bucks and is a 10 minute job and it made my gun feed like butter and chamber about any bullet I use. im sure it also lets your bolt go into battery much easier because the nose of the bullet isn't smacking into the forcing cone.

[Lloyd Smale]

9mm firing pins do have a spring.
That is a slam fire, where the bolt locks up and the FP has enough inertia to move forward and fire the primer.
In the cases where this happens typically commercial primers are being used, which are harder than mil primers.
A FP spring can mitigate this problem.
Militaries typically don't want to employ a FP spring as the fore/aft movement of a spring-less FP (imparted by the soldier walking with the gun)
"self cleans" the FP channel and helps prevent FPs rusting/crudding-up in place.

That is very different that the scenario shown in the OPs pics, which definitely fired out-of-battery, thus is not a slam fire.

[Elkins45]

My 9mm AR from PSA was a grenade waiting to happen. There wasn’t enough resistance to the bolt moving back under pressure. I had to add a heavier buffer and heavier spring to make it safe to shoot.

I think the 9mm AR is problematic in general. I’m probably going to get rid of mine.

[edp2k]

9mm firing pins do have a spring.

Of course colt-system 9mm ARs have a FP spring :)

if you read my post you will see it is in response to a comment regarding a so-called "original" AK which does not have a FP spring.
Also, to correct the term "original AK", which is a bit misleading, only a few AKs imported into the US for commercial sale had FP springs,
and those were later in the import game.

I recall that it was only very late polytech AKs that had the FP spring, after some experienced slam fires when using US made commercial ammo
which had relatively soft primers as compared to the foreign mil primers, and the large importer KFS (kengs) requested it, as he had some significant contacts in china.
All the AKs in use by foreign militaries and the vast majority of US imported AKs did not have a FP spring.

[nekshot]

I am all about having fun but these type of issues kinda common the way I am understanding this!!?? I feel real warm and fuzzy saying I don't have a blowback ar!

[M-Tecs]

ive got two 9mm ars and ill tell you what I think happened because it happened to me a number of times before I got my 4.5 inch gun worked out. There blow back guns. As soon as the primer ignites the charge the bolt starts back. If you don't have a heavy enough buffer or buffer spring the case can come back to far before the pressure has dropped and it will blow out the base of the case. Cure. run a 308 carbine buffer spring. At least a 5.5 oz buffer and NEVER put a reduced power hammer spring in one because the hammer spring is the first resistance the bolt has in its rearward trip. all three of these cures keep the bolt from coming back prematurely and the heavier buffer spring also helps the bolt come back into battery with more power. I also use a buffer spring cushion that goes on the back side of the buffer spring. It has a couple purposes. One is it keeps the bolt from coming back to far and breaking the bolt hold open if you have a colt mag gun that has a bolt hold open. It also shortens the stroke of your gun and helps the spring push the bolt back with even more speed. Id like to pretend to be the pro that discovered all of this but im not. I talked to a guy that does custom 9mm ars because I was having feeding problems and blown case problems like you. Since then ive put probably 2k threw the gun with a not a single case failure. Another good thing is a feed ramp. The barrel I got with my upper had about no forcing cone and most 9mm ars have no ramp (my cmmg does) . I was told to buy a faxom barrel because they had a more gradual forcing cone. 100 bucks later it didn't look a bit different. then I found where some are putting in a ramp. Its just a small piece that you inlet into your upper. think it cost like 20 bucks and is a 10 minute job and it made my gun feed like butter and chamber about any bullet I use. im sure it also lets your bolt go into battery much easier because the nose of the bullet isn't smacking into the forcing cone.

This would be my bet.

[tomme boy]

It was not the AK's that had a problem. It was the ndm-86 svd, and the SKS rifles. The SKS was because no one was cleaning the bolts and left the cosmo in them. Then they slam fired. And others did some bubba smithing on them to lighten the trigger. The spring that is used for the mag catch was the culprit. It lightened the trigger but also would make it go FA.

The SVD's from China were recalled to put a firing pin spring in them. Reason was they made this one in 308 win. And people running the commercial ammo were having it double triple and slam fire when closing the bolt. CDNN I think still has a recall on their web site for this rifle as this was where you got them from. So there are guns out there that never had it done. Reason for the ongoing recall

I don't ever recall the AK's being recalled for this or it ever added as a safety feature.

[FLINTNFIRE]

Its a blowback this is the issue , why is no working on a gas operated , I have owned a dozen sks and never has there been a issue of slam fire with any of them.

primers and firing pin springs are all good , but no firearm should be capable of firing till it is locked up , Yes I know there are a gross of builders parts and every one putting this and that together , and there is the issue , a little careless a little off put it in anyway , make it fit , lets fire it it is acceptable , on your own range by yourself maybe . oh it is someone elses spleen and insurance and all and there is a problem you have a accident and the other party ends up with a health issue . B.S.

[tomme boy]

The cmmg 9mm AR uses a modified bolt. It still has the regular(modified) bolt. It helps to lock it up so you don't get a OOB discharge. And it also keeps the firing pin shrouded till the bolt rotates and is closed before the hammer can hit the firing pin. Too bad it is patented because then everyone could use it.

[6bg6ga]

ive got two 9mm ars and ill tell you what I think happened because it happened to me a number of times before I got my 4.5 inch gun worked out. There blow back guns. As soon as the primer ignites the charge the bolt starts back. If you don't have a heavy enough buffer or buffer spring the case can come back to far before the pressure has dropped and it will blow out the base of the case. Cure. run a 308 carbine buffer spring. At least a 5.5 oz buffer and NEVER put a reduced power hammer spring in one because the hammer spring is the first resistance the bolt has in its rearward trip. all three of these cures keep the bolt from coming back prematurely and the heavier buffer spring also helps the bolt come back into battery with more power. I also use a buffer spring cushion that goes on the back side of the buffer spring. It has a couple purposes. One is it keeps the bolt from coming back to far and breaking the bolt hold open if you have a colt mag gun that has a bolt hold open. It also shortens the stroke of your gun and helps the spring push the bolt back with even more speed. Id like to pretend to be the pro that discovered all of this but im not. I talked to a guy that does custom 9mm ars because I was having feeding problems and blown case problems like you. Since then ive put probably 2k threw the gun with a not a single case failure. Another good thing is a feed ramp. The barrel I got with my upper had about no forcing cone and most 9mm ars have no ramp (my cmmg does) . I was told to buy a faxom barrel because they had a more gradual forcing cone. 100 bucks later it didn't look a bit different. then I found where some are putting in a ramp. Its just a small piece that you inlet into your upper. think it cost like 20 bucks and is a 10 minute job and it made my gun feed like butter and chamber about any bullet I use. im sure it also lets your bolt go into battery much easier because the nose of the bullet isn't smacking into the forcing cone.

sounds logical

[6bg6ga]

Brass looks surprisingly grungy to be factory

Grungy? Probably the result of going off without being 100% chambered.

[Lloyd Smale]

Yes and no. Yup the psa guns are basically starters. Minimum like I said is a 308 carbine spring, a heavy buffer and a extra power (or at least not a reduced power) hammer spring to hold the gun in battery a bit longer. Now my cmmg 16 inch 9mm has never one NOT ONCE missed a beat. Its probably the most reliable and forgiving ar I own and I own quite a few. Ive put every handload ive ever made for 9s in it. even that pointy 105 lee and it eats them all like candy. But then it was a 1000 dollar gun not a 500 dollar gun. Since I did those upgrades and put in that feed ramp on my psa gun its ran flawlessly too. I guess though id think it wouldn't cost them but a couple bucks more to do it right I the first place. Got mine running great now and id never part with it, even runs perfectly with cheap mags. It fits perfectly in a 10-22 take down case and its sits strapped to my roll bar over the rear tire well in the jeep. I painted over the ruger emblems and nobody would ever guess that little pack had a gun in it. ****?? it there with 5 30 round mags. I did here that the new version of psas 9mms have addressed some of these problems and do run better. But that said if you buy one youd better figure in about 75 bucks to get it running right. Before you give up look on psa web site. they sell that little feed ramp you fit into them. Heavy buffer (at least 5.5 oz) and even a standard length carbine spring will probably get you running perfectly.
My 9mm AR from PSA was a grenade waiting to happen. There wasn’t enough resistance to the bolt moving back under pressure. I had to add a heavier buffer and heavier spring to make it safe to shoot.

I think the 9mm AR is problematic in general. I’m probably going to get rid of mine.

[Lloyd Smale]

mine also has an actual feed ramp. that's the biggest thing that makes me shake my head with most blow back ars. No feed ramp what so ever. Just a bit of taper at the end of the barrel. I have to agree with you in that the cmmg bolt and barrel are the hands down best blow back ar system made. They just don't give them away though.

[243winxb]

Bullet set back from hitting a feed ramp on chambering may produce a kaboom, even in a low pressure 45 acp. This Hi-point 40 S&W Factory ammo at 35,000 PSI did kaboom.

The OPs photo shows a round not fully chambered when it fired. Was it going in or comming out of the chamber?

Blow back actions should not be made for 35,000 PSI cartridges. Imo.

[popper]

Wasn't slam fires that required the use of FP spring, they would go full auto.

[tomme boy]

PSA guns have a feed ramp on the bottom of the barrel now. At least mine does. Along with the cone all around the chamber. The feed ramp is not much but it is there.

I have mine sent back to PSA right now. The bolt is *****ed. I started to see wear on the outside of the bolt. It is nitrated so there should be NO wear. It is supposed to be the new wonder treatment for steel. Well it was wearing off all around the bolt. Then I checked the bottom of the bolt and it was ****ed up. There was a gouge in the receiver also.

https://www.ar15.com/media/mediaFiles/416992/Screenshot_20190514-055847-944688.png

[joatmon]

Dang!! And here I set just about ready to finish up my 9mm AR and now I see ABOUT ALL OF THIS! But now I can order the 308 buffer spring and heavy buffer.
Mighty glad I opened this topic. Aaron

[6bg6ga]

Recently shot my brothers 9mm AR build. It works flawlessly shoots anything and asks for more.

[Lloyd Smale]

holy ****! that sure got chewed up. I wouldn't be happy myself. I had a bit of wear on mine because the bolt was scraping on the ejector but a bit of filing on the ejector and readjusting it solve that. You don't happen to have a picture of that feed ramp on your barrel by chance?
PSA guns have a feed ramp on the bottom of the barrel now. At least mine does. Along with the cone all around the chamber. The feed ramp is not much but it is there.

I have mine sent back to PSA right now. The bolt is *****ed. I started to see wear on the outside of the bolt. It is nitrated so there should be NO wear. It is supposed to be the new wonder treatment for steel. Well it was wearing off all around the bolt. Then I checked the bottom of the bolt and it was ****ed up. There was a gouge in the receiver also.

https://www.ar15.com/media/mediaFiles/416992/Screenshot_20190514-055847-944688.png

[Lloyd Smale]

They been making blowback 9mms since before ww2. You can even get a blow back 10mm today. Blow back guns are no more unreliable then gas guns or locked breach guns. As a matter of fact some of the military guns that are considered to be the most reliable are guns like the Thompson that even fire open bolt. Ask some ww2 guys which gun was more reliable the Thompson or the m1 carbine that was gas operated. Mp5s are another. Even take a look around the internet doing a search for high point rifles and the #1 word you will hear is RELIABLE! Now some poor handloads that don't have enough neck tension or crimp sure can cause troubles in any gun. Take a 454 freedom arms pistol. A gun that's built like a swiss watch and load some full power stuff and us brass that doesn't have good neck tension or isn't crimped well and start shooting a cylinder. After each shot measure the overall length of the rounds remaining and you will find that without a good crimp you will get set back. Plenty enough to make pressures sky rocket.

So are we saying that a revolver should never be loaded past 38 spec pressures? Ive even seen rounds in a magnum bolt action gun get set back because of recoil. If blow back was actually dangerous do you think in this age of rem getting sued because people cant keep there finger off the trigger until they want there gun to go off that blow back guns would even be made? Nope. even gas guns can blow up if there not set up right or use sub standard ammo.

Actually if you look at a blow back Ar bolt youd see there much less that can fail. It doesn't have to rotate so its a one piece design. Doesn't need gas rings doesn't have a button and spring ejector, doesn't have a gas tube that can foul or need to be tuned for gas pressure. Doesn't need a gas block or gas block staking, Tuning is done with bolt weight, buffer and buffer spring. they don't have hot and DIRTY gasses channeled into the bolt. Things that some have switched to gas piston guns to get reliability. Same things you still have to do to tune a gas ar and they have to even be tuned for gas pressure. Once you learn the idiosyncrasy's of a 9mm ar there no harder to get to run right then any other ar. Ill say this. Ive got a 4.5 inch 9mm ar that I think runs just fine. You go and build yourself a 5 inch 556 or even a 7.5 in. My gun will run bullets from 120 to 147 loaded light or full power without change a thing. You take that little 7.5 or shorter 556 and run some 55s light and heavy and some 69s light and heavy and see if your gun runs them all without changing buffers springs gas pressure ect. Ive got a 100 bucks up against your 10 that my 9mm blow back ar has less hiccups then that little flame thrower you have. Did it come that way out of the box? NOPE it took some tuning and was a learning experience because tuning is different then a gas gun. That said my 16 in 300 bo need a heavier buffer to run right and took some grinding on the feed ramp to run cast bullets a 100 percent and even they is fussy which cast bullet it will feed (the 9mm feeds any cast bullet) My 8.5 inch 556 pistol took a heavier buffer and spring then the short pistol spring and 3.5 ounce buffer that came in the kit. It now runs a standard carbine spring and a 4.6 once buffer. Heck I still remember back in the day that guys would say just going to a carbine length gas system vs a rifle length original system made an ar unreliable.
Bullet set back from hitting a feed ramp on chambering may produce a kaboom, even in a low pressure 45 acp. This Hi-point 40 S&W Factory ammo at 35,000 PSI did kaboom.

The OPs photo shows a round not fully chambered when it fired. Was it going in or comming out of the chamber?

Blow back actions should not be made for 35,000 PSI cartridges. Imo.

[tomme boy]

Llyod, no I don't have a pic. PSA has it right now. Waiting to hear what they say. There was also a huge gouge in the rear of the receiver.

[243winxb]

Heavy springs and bolt that retard blow back , cause problems when they move forward. This is
more likely to cause slam fire or out of battery firings.

The 45 acp runs at 21,000 PSI, , less the the 22 lr at 24,000 PSI. COMPARING 9MM (35,000 PSI) + 10MM (37,500 PSI) hardly comes close..

Post #25 is a good example why i dont want a blow back carbine.

[Lloyd Smale]

Like I said if the dangers were real in this liability era were in they wouldn't be selling them. There have been open bolt and blow back 9mms since the 9mm was introduced. Problems come with guys that think they know more then the do. Just like the hack gunsmiths that adjust rem triggers. Now take a blow back 9mm ar and start doing back yard gunsmithing like putting a reduced tension hammer spring. Lighter buffer spring or buffer, Take the weight out of the bolt. Make sure you gun is nice and dirty so the firing pin sticks, feed it crappy handloads that don't pass a chamber drop test ect ect and you can make the do bad things. Set them up right and feed them right and keep them clean and they are as reliable and safe as any gun. Yup heavier springs cause problems when the bolt comes forward. Its why 9mm ars have a heavier buffer too. Twice as heavy as a 556. To slow the bolt down. Use a carbine buffer because you don't understand this and you will have trouble. I don't know if they address it with the new one or not but the problem that psa had wasn't using to heavy of a spring. It was using a heavy buffer with to light of a spring. they used a standard thickness carbine spring made lamer by cutting it to pistol length. This made it loose to much power and speed for the bolt going back into battery. Like I said the guys that know use full lenght ar10 carbine springs. Not only keeps more pressure on the bolt to delay it starting back but also gives that heavier bolt a better push back into battery. We can argue till the cows come home. Bottom line is im arguing with guys that haven't even tried it. Guys that are listening to what someone else heard for someone else who heard it from someone else. Like I said bring you gas impingement gun and a wad of money and first burp wins. You might win and you might not but before you even think about trying make sure your gun will run at least 500 rounds without cleaning and reoiling because mine sure will. Lots of guys claim that the gas impingement system is flawed and its why gas piston guns were made. Nothing like filling the inside of your bolt with carbon and gunk. ME? My gas impingement guns work just fine too. I know how to clean them

[Lloyd Smale]

by the way I found a cool use for my little 9. Found it fits perfectly in the little ruger 1022 take down case. Painted the ruger emblem black so it doesn't attract attention and stuck 4 30 round mags in the case with the gun and it sits perfectly on the wheel well between the roll bars feet in my jeep. Id bet about nobody would expect it was a gun let alone something with that kind of firepower in such a small package. Heck and you don't even have to put it together.

[tomme boy]

Lloyd. Supposed to have it back tomorrow. I will get a pic for you.

[Lloyd Smale]

thanks. Id like to hear what they had to say caused that extreme wear on the bolt too.
Lloyd. Supposed to have it back tomorrow. I will get a pic for you.

[dverna]

One reason I normally like to have another person with me when I am shooting is for safety. Stuff happens with any gun...even a bolt gun can have a case separation.

It is easy to think all is good. Especially when I have fired over 500k rounds without incident....but it only takes one bad event.

Reading posts like this are a good reminder for all of us.

[tomme boy]

Well the bolt showed up today. I just got another notification that the upper is shipped separate and will be here tomorrow.

Nothing in the box that said what happened.

[tomme boy]

Here is a pic. They replaced the upper receiver and bolt. Nothing was in either box to say what they actually did or what was the cause.

[jonp]

Pics#1 & #3 seem to indicate it wasn't fully chambered when the primer went off, which may mean that it fired while bolt is loading the round.
Good thing no one got hurt.

My guess, too but I don't have a pistol caliber AR

[Lloyd Smale]

is that cut in the lower part of the forcing cone what your calling a ramp? I did that to my first barrel with a Dremel and it did help a bit but made me nervous removing material that supported the case. That's when I bought the faxon barrel which was suppose to have a better forcing cone but I sure could tell the difference. It is a little more accurate but that might be just luck of the draw. there is a company that sells a barrel that has an actual ramp and a bolt cut to fit it https://taccom3g.com/product/5-25-9mm-ramped-barrel/. I just couldn't see buying a third barrel and another bolt when the 20 dollar add a ramp worked great. But if I was going to do a 9 today id buy a psa glock lower and a bare upper and go with the ramped barrel and bolt.
Here is a pic. They replaced the upper receiver and bolt. Nothing was in either box to say what they actually did or what was the cause.

[tomme boy]

Mine has fed everything so far.

[redneck1]

A popular misconception on blowback guns is that a heavier buffer spring will fix firing out of battery problems .

A simple fact is a heavier spring won't make any differance at all , if you'd like we can trot out the math , blowback guns rely on mass alone to delay bolt movement long enough for pressures to drop and not blow out the case .

The only purpose of a buffer / recoil spring is to return the bolt to battery to fire the next round .

I fully expect a few here to argue with me on that , before you do spend some time researching it .
I am no expert , but bolt mass is the entire reality with blowbacks.
Not mass and springs

Now there is one exception where a spring can make a differance , that is if the spring is short to hold the bolt into battery on a closed bolt gun .
A longer spring can fix this . A higher spring rate won't fix a short spring .

[Petander]

B&T APC9 bolt is heavy for a reason:

242673

[Lloyd Smale]

now answer me this. If I put a block of steel on a table and measure how much force it takes to get that block of steel moving and then repeat it with a big heavy spring behind it your saying that that spring has done nothing. Funny thing is that theres a company that specializes in 9mm ar15s. they build them and sell upgraded parts for them and even set them up to work a 100 percent with binary triggers. talk to them about what works and what doesn't. I did and the first thing they told me when I described my gun was to take out the reduced tension hammer spring and put a heavier (308 carbine) recoil spring. Now these guys have been there and done that. they KNOW what works. Even if it didn't (which it does) slow down the bolt from coming back the heavier spring surely adds velocity and power to the bolt return which would sure, by using common sense, tell me that theres a better chance that round is going to be shoved all the way into battery before my finger pulls the trigger.

There advice gets 9mm ars to run a 100 percent at the speeds you can manipulate a binary trigger. If you have some real world experience with 9mm ar15s then id sure would love to learn it. All I can say is mine has ran flawlessly since I took there advice and im sure since them ive put at least 2 or 3k though the gun.

My test for a new 1911 used to be oil the gun shoot a 100 rounds. Pull it apart clean it and run 500 through it without touching it. Clean it and do the same. If it passed that test id trust my life to it. Well this 9mm ar has easily topped that. Pretty good for a gun that is a defective design. Kind of like those unreliable glocks with there unsupported chambers. If you have any you should immediately ship them to me before one blows up and hurts you.

Lots of theory and to many gun design experts here and not much real world going to the range and making a gun go bang a few thousand times. Like I said bring your 556 and a wad of cash and we will do a shoot till somethings fails contest. Let me use my cmmg 16 inch 9mm and PLEASE bring your house title because that gun is the most reliable ar15 ive ever owned and came that way right out of the box. No moving ejector, rotating bolt with lugs that can break, no gas rings, plugged gas tube, gas block slipping out of position, no gas keys bolts to come loose, No bolt full of carbon inside, no lugs in the barrel that can plug up with grime of get a piece of brass stuck in them. No need to oil the locking lugs or bolt internals that's a magnet for fouling. light coat of oil on the outside of the bolt and when it gets filthy pull it out wipe it off put a light coat of oil on it as stuff it back in and keep going. Heck wipe it on your shirt and stick it back in. mine runs fine dry. Good luck when someone shooting back pulling your bolt apart to clean the fouling or digging out your gas key bolt that came loose and probably tore up the inside of your gun. Ill leave this one to the experts now. Other then hanging around to see how tomme's gun pans out. that is unless this thing fires out of battery and pokes my eye out.
A popular misconception on blowback guns is that a heavier buffer spring will fix firing out of battery problems .

A simple fact is a heavier spring won't make any differance at all , if you'd like we can trot out the math , blowback guns rely on mass alone to delay bolt movement long enough for pressures to drop and not blow out the case .

The only purpose of a buffer / recoil spring is to return the bolt to battery to fire the next round .

I fully expect a few here to argue with me on that , before you do spend some time researching it .
I am no expert , but bolt mass is the entire reality with blowbacks.
Not mass and springs

Now there is one exception where a spring can make a differance , that is if the spring is short to hold the bolt into battery on a closed bolt gun .
A longer spring can fix this . A higher spring rate won't fix a short spring .

[redneck1]

Eating lunch and I realized I forgot one thing in my post , if a gun is capable of firing out of battery , anything you do with recoil / buffer springs isn't fixing the problem . It may mask a few conditions
But it won't fix any of them .
If the hammer or striker can fall on the firing pin with the bolt out of battery that's a big problem .

[tomme boy]

I am in the same camp as Lloyd. Heavy bolt and buffer and a heavier recoil spring. The spring is the only thing that I have not got yet for mine.

Lloyd, took the gun out and the new bolt is starting to do the same thing after 50 rounds. PSA want the whole gun back. Just waiting on a shipping label from them. All those marks are impact marks by looking at the new bolt. I caught it soon enough this time. But what is actually doing it is the ????? The hammer looks like brand new. No sharp edges anywhere on it. It is happening on the left side of the bolt. Right at the ramp in front of the firing pin.

[Lloyd Smale]

are they marks possibly made from contact with the ejector? Do you have a pic of the new damage? Mine did that and I rounded the edges on the extractor and went on line and found how to adjust it. I couldn't blame psa for it though because I had a psa lower a different company upper and a different company yet bolt.
I am in the same camp as Lloyd. Heavy bolt and buffer and a heavier recoil spring. The spring is the only thing that I have not got yet for mine.

Lloyd, took the gun out and the new bolt is starting to do the same thing after 50 rounds. PSA want the whole gun back. Just waiting on a shipping label from them. All those marks are impact marks by looking at the new bolt. I caught it soon enough this time. But what is actually doing it is the ????? The hammer looks like brand new. No sharp edges anywhere on it. It is happening on the left side of the bolt. Right at the ramp in front of the firing pin.

[Lloyd Smale]

Again. What is your REAL WORLD experience with blow back guns. Did your corviar flip over, did your Remington rifle go off all by itself in the safe. Did someone smoking a cigarette a 1/2 mile away from you give you cancer? Did you have 2 glocks that blew up because they have an unsupported chamber and two more go off in the holster because they don't have a safety? Seems mine do one fine job of masking there problems. Do you have any real world advice to add here? Something you learned from actually shooting not the internet
Eating lunch and I realized I forgot one thing in my post , if a gun is capable of firing out of battery , anything you do with recoil / buffer springs isn't fixing the problem . It may mask a few conditions
But it won't fix any of them .
If the hammer or striker can fall on the firing pin with the bolt out of battery that's a big problem .

[toot]

I put all of my reloads in coffee cans or peanut butter jars. no confusion as to what they are. and put a piece of paper in them with load data.

[tomme boy]

Not the ejector. It rides in the cut out next to the marks.

242803

[Lloyd Smale]

please shoot me an pm and or post it here when psa figures out whats wrong. Looking at mine I just cant see what would case that damage. But like I said mine isn't a psa upper. But the wear must be coming from the lower rubbing somewhere.

[6bg6ga]

It would be nice if some of the posts were actually a product of personal experience instead of what someone read off the internet.

[Moleman-]

One of my uppers uses a PSA bolt, the others use a Spinta bolt. Made my own heavy 8 ounce buffers and barrels except I do have 1 AR-Stoner barrel that I recut the feed ramp on. Standard springs and no issues so far with hp, fmj/plated bullets or cast. I did have some feeding issues with a drop in magwell adapter, but ended up replacing them with dedicated lowers which seem to work much better for me.

[Shingle]

AR 9's will fire out of battery I had this happen with alum. case ammo several times due to the cases getting bent during loading then bolt cant close all the way and boom. I had it happen with 155gr. 9mm seated too long in just right carbine destroyed bolt both times . Most likely it is ammo related, thats where i would start.

[tomme boy]

Not all of them will. The new CMMG ones that use and actual bolt like a regular AR15 will not. Then there is a fellow over on ar15.com that makes direct impingement 9mm, 40, 45acp uppers. They use a regular bolt too.

Hammer follow on these will cause it too. But no one mentioned that.