S&W M&P15 Keyholing
- Thread starter Gatehouse
- Start date
Yup, if these have been Nitrided you should get around 20k through one.
How much higher? I was a bit surprised...but not that surprised. It's seen lots of extended shooting and the barrel has been smoking hot on many occasions.
I'm open to ideas
Nitriding forms a surface layer harder than chrome, I would expect at least 20k through it before a loss of accuracy is noticed.
I would contact whoever takes care of S&W warranty and see if you can get some compensation, it sounds like a lot of rounds but it's actually kinda premature.
Did you ever run any other ammo through it? Maybe some of that Norinco crap?
Last edited:
![-[Crosshair]-](/forum/data/avatars/m/31/31565.jpg?1718745216){kind=avatar}
Just so you know, Colt Canada's high-quality cold-hammer forged barrels with the thicker chrome have a life of around 20,000 rounds. American M16 and M4 barrels do not even have half that life span (8,000 rounds if I remember correctly).
10,000 rounds out of these entry-level AR-15s is completely normal. I would not expect these to go anywhere near 20,000 rounds, that's a HIGH round count.
Only ammo I've used has been PMC and mostly Federal. I actually just noticed I have some Tula and MFS steel cased stuff here too, so I am going to try that out today. I suspect it will also keyhole but who knows
What will be interesting to see is how one of my other M&P's reacts. They were both bought at the same time and both have a similar round count. Will be interesting to see if the other one starts keyholing soon too.
What will be interesting to see is how one of my other M&P's reacts. They were both bought at the same time and both have a similar round count. Will be interesting to see if the other one starts keyholing soon too.
I think you have to take into account the time frame those rounds were fired through the gun. The rifle has probably been owned for less than a year (guessing from when they were selling for $6-700) and as Gatehouse said, it has had a lot of extended, hot shooting.
10,000 rounds over 5-10 years is different than 10,000 rounds in 6 months.
10,000 rounds over 5-10 years is different than 10,000 rounds in 6 months.
That’s the question- New barrel $300-400. Whole new rifle $600
Although I haven’t looked too hard for barrrels. Maybe there are some suitable ones in the $200 range
Nitride is harder than chrome. I had a PWS AR and contacted PWS directly to ask about barrel life and was told they have tested their barrels to 20000 rounds without a loss of accuracy .
Chrome lining is old technology, nitride is more consistent meaning more accurate than the same barrel if it was chromed and longer wearing than chrome.
Just so you know, I don't care how long a Colt double chrome barrel will last, this isn't one of them and the barrel in question should have lasted more than 10000 rounds.
Op, For a $600-$700 AR I'd say you got your money's worth and wouldn't argue too hard with the warranty department but it's worth a try.
I'd watch the EE for a decent barrel in the $200 range and throw it in there if warranty won't cover replacement.
How's the rest of the rifle holding up? $600 is a pretty good deal if after 10000 rounds all it needs is a new barrel.
True, I didn't think a $600 entry-level S&W rifle would have a great, long-lasting barrel compared to a company that is known to make some of the longest lasting barrels in the world with thick chrome that are also cold-hammer forged precisely for longetivity for customers that dump rounds through them like it was nothing. Barrels that truly have an average life of 20,000 rounds. That nitide treatment turns that cheap S&W barrel into something it's not.
But hey, rest assured S&W will replace a worn out barrel with 10,000 rounds through it under warranty, I'm not the one with delusional expectations.
True, I didn't think a $600 entry-level S&W rifle would have a great, long-lasting barrel compared to a company that is known to make some of the longest lasting barrels in the world with thick chrome that are also cold-hammer forged precisely for longetivity for customers that dump rounds through them like it was nothing. Barrels that truly have an average life of 20,000 rounds. That nitide treatment turns that cheap S&W barrel into something it's not.
But hey, rest assured S&W will replace a worn out barrel with 10,000 rounds through it under warranty, I'm not the one with delusional expectations.
I only said it's worth a try asking, I don't expect them to replace it and I wouldn't argue with them if they say no.
Op,
https://www.canadiangunnutz.com/forum/showthread.php/1757480-AR15-PARTS-14-5-inch-Barrel-MAGPUL-Grip
Sorry it's an NEA but it's cheap and NEA barrels aren't usually too bad. Button rifled and nitride usually.
A little digging and
Early S&W M&P rifles came with an 8 twist 5R rifled barrel made from 4140 steel and Melonite treated.
Sport II rifles come with a 9 twist traditionally rifled barrel made from 4140 steel and Armornite treated.
Armornite is S&W's name for nitriding which is the same as Melonite. They couldn't use the term Melonite any more due to copywrite or something along those lines.
These sound like decent barrels considering how cheap the rifle is.
Early S&W M&P rifles came with an 8 twist 5R rifled barrel made from 4140 steel and Melonite treated.
Sport II rifles come with a 9 twist traditionally rifled barrel made from 4140 steel and Armornite treated.
Armornite is S&W's name for nitriding which is the same as Melonite. They couldn't use the term Melonite any more due to copywrite or something along those lines.
These sound like decent barrels considering how cheap the rifle is.
Last edited:
Barrel life expectation is conditional. Rate of fire and type of projectile jacket are main factors IMO (there were some tests that killed barrel with 4,000 steel jacket projectile where copper jackets caused no harm on 10,000). You can easily kill most of MG barrels with continuous fire. And here we are talking about semi-auto rifle barrel. So simple round count means not much.
I can't find right now but I think I saw report of 12 or 13k out of Sport 2 and it was still running.
I can't find right now but I think I saw report of 12 or 13k out of Sport 2 and it was still running.
That’s the question- New barrel $300-400. Whole new rifle $600
Although I haven’t looked too hard for barrrels. Maybe there are some suitable ones in the $200 range
Check out the M&P at Firearms Outlet Canada, they might have made the decision for you.
So, more fun stuff. I have 3 of these M&P's. They all have different colour magpul furniture. The black is the one we are talking about, and I bought it at the same time as the grey one. Tan one is newer.
Black and grey have similar round count, although black is slightly higher.
Today I tried TULA and MFS ammo just for fun, as well as the Federal that has been keyholing.
At 100 M
Black
TULA-keyhole
MFS- keyhole
Federal- keyhole
Grey
TULA- clean holes
MFS- slight keyhole with some
Federal- slight keyhole with most
The TULA is known to be hot, so maybe the extra velocity is helping for now. But it looks like the grey barrel is on it's way to being pooched too.
Overall the S&W rifles have been very good, they feel nice and operate well. Don't break. I would like a bit longer barrel life, but it's hard to get upset at a round count in the 9-10K range from a budget AR.
Black and grey have similar round count, although black is slightly higher.
Today I tried TULA and MFS ammo just for fun, as well as the Federal that has been keyholing.
At 100 M
Black
TULA-keyhole
MFS- keyhole
Federal- keyhole
Grey
TULA- clean holes
MFS- slight keyhole with some
Federal- slight keyhole with most
The TULA is known to be hot, so maybe the extra velocity is helping for now. But it looks like the grey barrel is on it's way to being pooched too.
Overall the S&W rifles have been very good, they feel nice and operate well. Don't break. I would like a bit longer barrel life, but it's hard to get upset at a round count in the 9-10K range from a budget AR.
yeah, that's a good deal. And maybe nothign wrong with rotating out AR15's every year.
So it looks like with your pattern of usage and type of ammo 9-10k is the limit. Not bad for budget AR, even US army has what 9.5k? I think you mentioned in another thread you've put them through some extensive firing. Can you elaborate on this? Have both black and grey were exposed to that?
They are range guns and both get used the same, a few people want to do mag dumps, most shoot more slowly. But they often have 100 rounds or more through them in 15 minutes so they will get hot. What’s also interesting is that they were very accurate for a long time, then all of a sudden went to keyhole.
I was looking on their site and adding another S&W to the cart and I stumbled on this, which isn't a bad solution to the problem, at $250. No need to #### around with removing front siight/gas block, just install a new gas tube and done.
Aero Precision 16" 5.56x45 CMV AR15 Barrel w/ Pinned FSB - Carbine Length
