Bolt not locking back after last round fired

[High Exposure 5,676]

The .223 loading is? I thought the 5.56 loading with the bonded bullet was the preferred ammo for LE work?

We don't use barrier blind ammo for most jobs, especially on a SWAT team where we spend most of our time in and around buildings rather than cars. The T223L performs reasonably well through intermediate barriers like auto glass in a pinch, just keep shooting

 

According to Dr. Gary Roberts:

In those situations where intermediate barrier penetration is not a critical requirement, for example LE urban entries or long range shots in open conditions, then OTM, JHP, and standard JSP loads can offer acceptable performance. For 1/7 twist barrels, the Hornady 75 gr OTM, Nosler 77 gr OTM, and Sierra 77 gr SMK OTM are all good choices. The experimental BH loaded 100 gr OTM exhibits impressive fragmentation, even at relatively low velocities, however while capable of shooting out to 600, it is optimized for 200 and under. If stuck with 1/9 twist barrels, the heavy 70+ gr loads are not universally accurate in all rifles and the 69 gr SMK OTM, the 68 gr Hornady OTM, the Winchester 64 gr JSP (RA223R2), the Federal 64 gr TRU (T223L) JSP, Hornady 60 gr JSP, are likely to run accurately in the majority of 1/9 twist rifles. Again it is critical to keep in mind that the above loads fail to offer adequate penetration through intermediate barriers.

The barrier "blind" loads are a mix of 5.56 and .223 bonded offerings.

 

 

 

IMI is not rejects. It's military ammo. It's better than US Military ammo.

The reason US ammo is "XM" is because it is illegal to sell US Military surplus ammo (Thanks Clinton!!!).

The "X" does NOT denote rejected ammo.

It's just made specifically for the civilian market. If it was all rejects, then Lake City would have double digit failure rate in their production. They produce way too much XM ammo for it to be rejects. Heck, Lake City doesn't even make ANY M193 anymore (Israel does), so there is no way there XM193 is exclusively rejects.

A small portion of the ammo was probably made from pulldown components that failed mil spec for minor reasons. But certainly not the majority of it.

There was a time when Lake City was producing hardly any XM855 for the civilian market back in the early 2000s and a lot of the "XM855PD" did indeed look like it had a high percentage of rejects. Those days are long past.

In my experience the days of bad ammo are from from long past. I am increasingly reluctant to take the word of ammo manufacturers at face value. Yes, "X" lots may in the words of ATK be:

 

All our Xm193 ammunition is manufactured by LCAAP and is first

production run, the XM193 is a 5.56 cartridge and is not interchangeable

with the 223. The Xm855 is also first production run made by LCAAP in

5.56 and is load with a steel penetrating bullet.

But that sounds like some serious corporate doublespeak by a manufacturer that has some product that is in great demand but doesn't quote meet the spec. They may be first production run but that doesn't mean that it simply didn't meet the original spec the rounds were destined to be manufactured to when they rolled off the assembly line, so they became "civilian market" specific ammo. It is all semantics.

 

Also, I don't trust anything from the Isreali Military. Not their equipment, not the ammo, and certainly not their TTPs.

[raz-0 1,259]

IMI is the Isreali Milsurp ammo right? Generally it is labeled as "XM" in this instance "XM855". The "X" denotes it was a rejected lot. I wouldn't trust that to trouble shoot a BCM. That just me though.

 

http://www.thegunzone.com/556xm.html

 

The XM thing is a federal thing, and no it doesn't mean it was rejected. It means it was overrun. I.e. it is not contract ammo and does not have to be pulled down and sold as components to be sold. 

 

PD is another matter. I haven't seen PD stuff in FOREVER, and when I had, there were some people having some odd issues with it. Last time I saw any was maybe 2004? Like I said, a while. 

[mipafox 438]

 

  

 

 

What's wrong with .223?

 

I use Fed TRU 62gr Hi-Shok SP (http://le.atk.com/ammunition/federal/rifle/details.aspx?id=684) which is a .223 offering for all my guns set up for social purposes - including HD. It is also the standard issued round for many LE agencies and SWAT teams - mine included - and is regularly in the top choices of available rounds out there by the better known ballistics guys.

Your gun isn't short-stroking on full-power military 5.56.

 

If it was, I would strongly suggest NOT betting your life on .223 ammo.

[mipafox 438]

In my experience the days of bad ammo are from from long past. I am increasingly reluctant to take the word of ammo manufacturers at face value. Yes, "X" lots may in the words of ATK be:

 

 

But that sounds like some serious corporate doublespeak by a manufacturer that has some product that is in great demand but doesn't quote meet the spec. They may be first production run but that doesn't mean that it simply didn't meet the original spec the rounds were destined to be manufactured to when they rolled off the assembly line, so they became "civilian market" specific ammo. It is all semantics.

 

Also, I don't trust anything from the Isreali Military. Not their equipment, not the ammo, and certainly not their TTPs.

Do you know how old that comment is? Lake City doesn't even make any M193.

 

Despite the fact that the comment is so old, I think the guy made it clear he didn't even know exactly what he was talking about. There have been dozens of comments from Winchester (back when they ran it), Federal, ATK, and Lake City on what XM ammo is and is not. Not all of the answers have been 100% consistent, but most of them have been pretty close to what I said:

 

1. The ammo is not rejects - that's impossible, they make way too much of it for it all to be rejects.

2. XM193 can't be all rejects - Lake City doesn't make any M193 anymore. They have no military contracts for 55 grain ammo.

3. Some of it may contain pull-downs from off-spec production that wasn't accepted by the military.

[High Exposure 5,676]

 

 

Your gun isn't short-stroking on full-power military 5.56.

If it was, I would strongly suggest NOT betting your life on .223 ammo.

I see what you are saying now and I agree. Also, I wouldn't bet my life on a gun that was short stroking anything. But that's a gun issue, not an ammo one.

 

As for the ATK reps response, that was about 3 years ago. When I say rejects, I mean it was found to be lacking in some way from the mil spec: Cosmetic, shape, power, not annealed, not crimped, primer not staked/boxed etc.... It may be made that way on purpose, it may function fine, but it wouldn't pass mil-spec inspection.

[Old School 611]

[mipafox 438]

As for the ATK reps response, that was about 3 years ago. When I say rejects, I mean it was found to be lacking in some way from the mil spec: Cosmetic, shape, power, not annealed, not crimped, primer not staked/boxed etc.... It may be made that way on purpose, it may function fine, but it wouldn't pass mil-spec inspection.

I understand. No, XM ammo is not rejects, or ammo that was found lacking in some way, and most of it would probably pass mil-spec inspection. It may contain pull-down components, and some of it might not pass mil-spec inspection. But it is not ammo that was set aside for missing spec.

[High Exposure 5,676]

Interesting but I am still suspect.

 

I believe, and my research points to, it is purposefully built to not meet the spec, making it cheaper to produce while allowing premium prices on the "Civilian" market for "Military" ammo by naming it XM855, since they can't call it M855. It's a shell game.

 

Caveat: There are some loads that are purposefully labelled "X" such as XM556FBIT3.

 

I just realized that I am very jaded by the commercial ammunition industries practices after witnessing decline into the the poor quality of ammo we currently have over the last 5 years or so... If this was what was available 10-15 years ago everyone would be screaming their heads off. As it stands now, we eat their shit and ask for seconds while thanking them... But I digress...

[Sig226GuyNJ 128]

The buffer did not have any markings on it and I don't have a scale to weigh it either. Would it be correct to assume this is a commerical buffer and not milspec? I was unable to measure the spring due to my son crying, but will try and get to that tonight.

[MidwestPX 172]

The buffer did not have any markings on it and I don't have a scale to weigh it either. Would it be correct to assume this is a commerical buffer and not milspec? I was unable to measure the spring due to my son crying, but will try and get to that tonight.

Commercial vs. milspec refers to the diameter of the receiver extension, not the buffer weight. My guess would be it's a carbine weight.

[Displaced Texan 11,779]

OP,

If you need a carbine buffer I have one I'll give you.

 

Let me know if it will help.

[Sig226GuyNJ 128]

Commercial vs. milspec refers to the diameter of the receiver extension, not the buffer weight. My guess would be it's a carbine weight.

Do you think the weight of the buffer would have any effect as far as short stroking? Or do you think the spring is more of a factor?

 

OP,

If you need a carbine buffer I have one I'll give you.

 

Let me know if it will help.

Wow. Thank you for your offer sir. Before I take you up on it, I would like to pinpoint what the exact issue is, so I don't take something that I don't need. Again, much appreciated sir.

[MidwestPX 172]

The buffer weight can most certainly affect cycling and mimic short stroking.

[Displaced Texan 11,779]

Midwest PX is absolutely correct, too heavy of a buffer can cause cycling issues and shirt stroking.

 

My offer stands, if you need it, please let me know.

[checko 180]

If its a carbine buffer as suspected it shouldnt affect it much. I'd look at your gas system (gas port, gas key etc)

[Sig226GuyNJ 128]

The buffer weight can most certainly affect cycling and mimic short stroking.

Makes sense.

 

Midwest PX is absolutely correct, too heavy of a buffer can cause cycling issues and shirt stroking.

 

My offer stands, if you need it, please let me know.

Thank you!

 

If its a carbine buffer as suspected it shouldnt affect it much. I'd look at your gas system (gas port, gas key etc)

Gas port looks fine and keys look properly staked. I will take pic and post up to see if you guys think otherwise. Thanks everyone!

[pbkid6974 1]

What length gas system was the original m&p upper? I have a bcm midlength and h buffer and I've never had a problem cycling anything. Even cheap steel case ammo. My gun eats everything. Maybe you need a bolt catch spring? I doubt that's the issue but you should change it out anyway just in case.  

[raz-0 1,259]

I see what you are saying now and I agree. Also, I wouldn't bet my life on a gun that was short stroking anything. But that's a gun issue, not an ammo one.

 

As for the ATK reps response, that was about 3 years ago. When I say rejects, I mean it was found to be lacking in some way from the mil spec: Cosmetic, shape, power, not annealed, not crimped, primer not staked/boxed etc.... It may be made that way on purpose, it may function fine, but it wouldn't pass mil-spec inspection.

 

I've gone through thousands of rounds of the stuff and never found one that was not annealed, staked, crimped or anything other than very slightly tarnished bullets or brass.  Since to sell it can't be military contract ammo, it is just "overrun" I.e. planned usage of the facility to make commercial ammo. I also suspect that they may not perform the mil-spec accuracy checks and power checks at the same intervals they would for contract ammo. SInce in every regard including price it appears to be the exact same stuff as in american eagle boxes,  I would suggest it is as reliable as any high volume, lower priced commercial blasting ammo. 

 

BAck when they had the PD boxes, people got some funky stuff. I even got some seriously dented and banged up ammo out of that. 

[ChrisJM981 924]

I had the same problem. For me it was the buffer spring. I had a DPMS spring in there. Bought one of these: http://www.jprifles.com/buy.php?item=JPS-OSC

 

Problem solved.

 

Oh and no more rattling.

[raz-0 1,259]

I had the same problem. For me it was the buffer spring. I had a DPMS spring in there. Bought one of these: http://www.jprifles.com/buy.php?item=JPS-OSC

 

Problem solved.

 

Oh and no more rattling.

 

Just FYI, the JP springs are very nice, but they are increased spring rate over standard. Maybe 10%, not sure. I had a build that had some issues, JP springs made it stop working 100%. Not that the springs are bad, jsut that they can confuse diagnostics if you aren't aware they are a different spring rate, which I was not at the time. 

[Sig226GuyNJ 128]

Ok, so this is really embarrassing to admit but I'll admit it anyway. I found out why my bolt was not locking back.....

 

Not enough lube! Yep. What an amateur I am...

[Sig226GuyNJ 128]

Odd, is it well lubed?

I guess my idea of well lubed is not enough..

[checko 180]

I guess my idea of well lubed is not enough..

Run it hard and wet. That's what I always say.

[Displaced Texan 11,779]

Glad you figured it out. Don't be afraid to lube the snot out of it.

I have become very fond of Mobil 1 synthetic oil (0W-40) lately as a weapons lube.

[Sig226GuyNJ 128]

Glad you figured it out. Don't be afraid to lube the snot out of it.

I have become very fond of Mobil 1 synthetic oil (0W-40) lately as a weapons lube.

 

Jeff, would you like your buffer and spring back?

[Displaced Texan 11,779]

No sir, keep it. It may grow into another rifle.

[Sig226GuyNJ 128]

No sir, keep it. It may grow into another rifle.

Much appreciated it sir!

[Displaced Texan 11,779]

You won't be thanking me when it grows into another AR. You, and your checkbook will be cussing me.

 

Lol

[Sig226GuyNJ 128]

One more question for the experts. While troubleshooting my AR, I put in a different stock on. Still using the same buffer and spring. However, the buffer now slides a bit up and down inside the tube. My old stock had something in it to prevent this from happening. What is it? And where can I buy one?

[checko 180]

What stock is it?