New m&p10 cycling issue

[Cc426]

Hi guys, new to this forum, thought this would be the best place to ask.

Having problems with my new m&p10 short stroking. Shooting 308 (not the NATO rounds) factory loads. Tried 168, 145 couple different brands ppu, fiocchi, freedom munition

Bolt is not traveling far enough to strip a round. Not enough force to chamber a round or go into battery. Not holding open on last shot

Seems to malfunction about 1/5 rounds or so. Shot it for the first time today, went through 75 rounds. Cleaned, greased, and oiled it before I took it out.

Also when trying to remove or insert the bolt with the gun disassembled I can feel more resistance (pretty significant difference) when the bolt is about halfway into the upper through being completely inserted.

Doesn't look like there are any obstructions...ideas? Was your bolt tight fitting new? Will the tightness just work itself out after break-in?

Thanks

 

[ohiowolverine]

This happened to me the first time I shot it. Next time I went, the problem went away. I am thinking it is just a tough gun to break in. Don't use crappy ammo either (CBC).

 

[ole-cowboy]

Also when trying to remove or insert the bolt with the gun disassembled I can feel more resistance (pretty significant difference) when the bolt is about halfway into the upper through being completely inserted.


Thanks

this statement is troubling, BCG should fall out on its own weight... I would cycle the **** out of it, either by hand or by shooting it and look for wear marks....then go from there

 

[Cc426]

this statement is troubling, BCG should fall out on its own weight... I would cycle the **** out of it, either by hand or by shooting it and look for wear marks....then go from there

Looks like there is wear on the finish of the bcg on the top rails by the gas key, the upper doesn't look like there's any significant wear on it

 

[Blueapplepooh]

There was wear marking on both my upper and BCG, the more the firearm cycles, the better it gets...

All I can say, new platform, we have (assuming) the first batch of these rifles, if it doesn't get better, contact S&W for a service tag and get her looked at.

 

[tomclev]

Having the same problem. Have you noticed scratched up brass on your rounds? Pict of dummy rounds with the scratches I'm getting ...

 

[vfin]

Bend the two long sides of your S&W M&P10 magazine(s) to be a little (very little) more open...and I'd bet your problem will be solved.

If you noticed, like I did, the mags sides are really tight against the rounds, and hand stripping out a few single rounds will show you that the mag side ears really dig into (scratch) the heck outta shell casings as you hand slide them forward. Way too tight my friend.

Loosen it up !

vfin :::and get yourself lithium grease to lubricate the heck outta all parts, as well as a new "Raptor" ambidexterous Charging Handle:::

 

[Swannie]

I was having the same problem with rounds not feeding correctly. Only I couldn't fire more than one or two rounds consecutively without a failure to feed. I was only able to fire about 12 rounds when I got fed up with everything and switched to another gun. I am also getting long scratches or scrapes on my brass and gouges in the copper jackets of the rounds. I was firing Federal Premium ammo.
On the range it looked like the rounds were getting stuck on the magazine or ramps. I'm not an expert and this is my first foray into AR style rifles. The game warden on the range suspected it is something with the ramps, but I don't know. Also some of the rounds that didn't fire, but were jammed came out with burrs and dented shoulders.
I've already sent my rifle and magazine back to S&W to let the experts look at it. I'll let y'all know if they tell me what was wrong with it.

PS We oiled the bolt carrier group or bolt assemble very liberally while trying to troubleshoot my rifle.

 

[tomclev]

Appreciate the continued feedback .... Hopefully going out to the range today to try and loosen things up .... Since I'm using the Magpul PMAG hard plastic magazines, I'm not convinced they are the problem. Use them with my LWRC R.E.P.R and have no problems.

 

[rojodiablo]

Bend the two long sides of your S&W M&P10 magazine(s) to be a little (very little) more open...and I'd bet your problem will be solved.If you noticed, like I did, the mags sides are really tight against the rounds, and hand stripping out a few single rounds will show you that the mag side ears really dig into (scratch) the heck outta shell casings as you hand slide them forward. Way too tight my friend.

Loosen it up !

vfin :::and get yourself lithium grease to lubricate the heck outta all parts, as well as a new "Raptor" ambidexterous Charging Handle:::

Anything in bold, I would recommend against highly. In fact, what I would suggest about this advice would get me another visit by the site Gorilla..........

Take ANY number of brand new and used magazines for this rifle. Pmags, DPMS, and try to just push ammo out of them with a full magazine. They tend to be TIGHT- for a reason. Test a Pmag..... Load it full and toss it over your shoulder into the dirt, good and high, good and far. See how much ammo falls out. (None) As it SHOULD BE. Do NOT oil or lube ANY part of a magazine. No matter how tempting that is, do not do it. If you DID, then clean it out but do NOT use brake cleaner, etc. solvent on any plastic parts of the magazine. Clean them with simple green, dish soap, etc.
Grease; whether it be Valvoline bearing grease, lithium grease, or hog fat rendered is NOT ideal for these rifles. Oil. Use an OIL. Grease is smooth when hot. As it cools, it gets sticky. When it gets contaminated with ANYTHING, it is not only sticky, it becomes a grinding paste. Rub the grit of 100 shots fired from your chamber between your fingers. Gritty....... Now, put that in grease, and start rubbing on things. See how well it polishes and grinds away stuff?
For a brand new rifle, this may help with break in. BUT; it is NOT ideal for long term use. Furthermore, the grease will flow when hot, and get into things like your bolt, rings, and extractor. Then, when the grease cools, those parts will have much more stiction because the grease turned into slimy glue with the powder residue as a binder.

Do not bend feed lips on a magazine which has not been disproven, ESPECIALLY when the rifle in question has a history of being a tier 1 short-stroker. What ALL your short-stroker rifles need is to add a little weight into your buffer tube. A small piece of foam, and a 1/4-3/8oz fishing egg sinker, a small drift pin, and a few minutes of time will fix this problem for ALL of you.

And oil. Christ on a bicycle; the rifles like OIL. It says as much in the manual. The .mil does not give you a grease gun in basic and tell you to hit the zerk behind the barrel, and the one under the trigger for a reason...... the rifles use oil, not grease. Grease will stick and slow down the stuff that is supposed to move with minimal contact; the BCG uses glide surfaces, not an enclosed bolt assembly like say a model 700 deer rifle. And I wouldn't use grease there, either.

 

[rojodiablo]

Having the same problem. Have you noticed scratched up brass on your rounds? Pict of dummy rounds with the scratches I'm getting ...

Ahhh, pics. Stuff of the Gods!

Question for you: Will it strip a round cleanly when the bolt is manually operated, time and time again? Please give results from 10 tries. Even if you have to force the bolt into battery each time with the FA. ( Bolt speed will be so slow manual feeding the bolt may not have enough 'oomph' to drive the bolt home. Not a problem nor an issue.)
Will the bolt drop from the retracted position and strip a round dependably 10 out of 10 times? Open bolt, latch open. Then, let fly with the bolt release button. Please give results from 10 tries.
If the rifle cycles 10 of 10 manually, then the issue is NOT the magazine most likely. The bite marks tell the story of a strong buffer spring and a light buffer, meaning the bolt is traveling too fast. More dwell time is the proper answer, the fix is a slightly heavier buffer.

Good pics, thank you. That helps.

 

[tomclev]

Cycling Issue

Sounds like I am getting more out of this post than the originator! .... Sorry!

I ran 10 dummy rounds through again and it seemed that the operation went smoother each time .... Ran 5 more live rounds through (Fed Premium 168gr BTHP) (see attached) and got slight scratches and dings. Then ran 5 more through and they came out pretty much unscathed.

Seems like it is operating smooth during both the feeding and extraction cycles ....

Still need to hit the range .... hoping this week.

Ahhh, pics. Stuff of the Gods!

Question for you: Will it strip a round cleanly when the bolt is manually operated, time and time again? Please give results from 10 tries. Even if you have to force the bolt into battery each time with the FA. ( Bolt speed will be so slow manual feeding the bolt may not have enough 'oomph' to drive the bolt home. Not a problem nor an issue.)
Will the bolt drop from the retracted position and strip a round dependably 10 out of 10 times? Open bolt, latch open. Then, let fly with the bolt release button. Please give results from 10 tries.
If the rifle cycles 10 of 10 manually, then the issue is NOT the magazine most likely. The bite marks tell the story of a strong buffer spring and a light buffer, meaning the bolt is traveling too fast. More dwell time is the proper answer, the fix is a slightly heavier buffer.

Good pics, thank you. That helps.

 

[rojodiablo]

Sounds like I am getting more out of this post than the originator! .... Sorry!
I ran 10 dummy rounds through again and it seemed that the operation went smoother each time .... Ran 5 more live rounds through (Fed Premium 168gr BTHP) (see attached) and got slight scratches and dings. Then ran 5 more through and they came out pretty much unscathed.

Seems like it is operating smooth during both the feeding and extraction cycles ....

Still need to hit the range .... hoping this week.

Actually, everyone who has a similar issue with their rifle gets the information even faster and finds a cure faster, because you asked about issues as well as the OP.
From what I know about the bigger AR's, they need some more break in than the 15 does. It might be due to the parts size being larger, all the wear surfaces and parts need to be exercised to get to a point of smooth operation.
I have dealt with a lot of DPMS, BM, and others with this platform, and it seems to be a consistent thing with about 40% needing some round count stacked up to get them running free.

 

[tomclev]

Thanks ... appreciate the feedback!
Since I have the LE edition I was not sure if it has different spec springs, etc. (My LWRC requires M118LR spec >168gr or higher rounds due to barrel twist and back pressure design features).

 

[vfin]

"Break In Period? (For a Smith & Wesson?)

It's an "URBAN MYTH"

vfin

 

[Cc426]

Ok. To give everyone an update. My rounds were stripping out of my mag, but were just "hanging out" and the bolt wouldn't go into battery. Most the time it wasn't even a jam, just the bolt got stuck after stripping the round and didn't have enough energy to go completely into battery.

I've since been out to the range 2 more times. The first of these two times I ran 80 rounds through it, and only had the problem maybe 3-4 times, and only when the mag was full and only on the 2nd round.

The last time I was out I put another 80 rounds through it flawlessly with no jams. I've greasing the rails of the bcg and then oiling the heck out of it until it is literally dripping.

The bcg now can be removed and put back into the upper more smoothly, but does still take some effort and binds a bit when removing it by hand to field strip. However it is not really noticeable when racking it with the charging handle while assembled.

I think for me it was a break in issue. Just all the parts fitting too tightly. After 3 cleanings and 200 rounds it now seems fairly reliable. The rifle shoots fantastic and is definitely a sub moa gun out of the box with good ammo, it seems to like anything 168gr match doesn't matter what brand...

On a side note, is anybody else's rear takedown pin ridiculously tight? I've greased mine and it still needs to be tapped out with a tool, I can't push it out with just my hands.

 

[rojodiablo]

Thanks ... appreciate the feedback!
Since I have the LE edition I was not sure if it has different spec springs, etc. (My LWRC requires M118LR spec >168gr or higher rounds due to barrel twist and back pressure design features).

I have to ask; what is the length and twist on the barrel? Which piston setup; adjustable or fixed? What length gas system?
EVERY LWRC I have dealt with was tunable, and could be made to shoot just about anything from blackpowder to Trident missiles.
The only kicker was tuning the gas port to work with basically all ammo types; some guys want the rifle tuned to the oompth degree to 'soften' recoil as much as possible and the rifles were very picky eaters. On the other hand, the REPR I had would eat ALPO dog food and ask for seconds. It might have kicked a tiny bit harder, or thrown brass an extra 2 feet. But it would eat Wolf/WPA ammo without complaint.

You might need to tune that rifle a little bit; make the safe queen into a little bit of a junkyard dog!!!

 

[tomclev]

From the web site .... I have shot about 120 rounds of the Federal 168gr BTHP ... no issues and the rifle is highly accurate! I have the 16.1" barrel ...

Caliber: 7.62 NATO/.308 Winchester
Barrel Length: 16.1", 20"
Weight (unloaded): 9.5lbs (16.1"), 11.25lbs (20")
Length (overall): 40.8" (16.1"), 41.5"(20")
Rate of Fire: 55 RPM (Sustained ROF)
Rifling: 1/10" RH; 1/11.25" RH (Optional)
Stock/Pistol Grip: 16" B5 Systems SOPMOD, 20" Magpul PRS/Magpul MIAD
Sights: LWRCI Folding BUIS Front and Rear
Magazine: Magpul 20 rd. PMAG 20LR
Muzzle Device: A2 Birdcage 5/8x24 TPI

The unique LWRCI™ Rapid Engagement Precision Rifle (R.E.P.R.) is a full spectrum weapon system designed to put devastating 7.62mm NATO rounds on target in a variety of roles. The R.E.P.R. rifle allows a marksman to perform assaulter duty with the 16" barreled upper installed, and quickly switch to a sniper role simply by changing to the 20" barreled upper. The extra upper receiver assembly can be carried in a backpack and takes up less room and weighs less than carrying a separate rifle.

The R.E.P.R. rifle utilizes our patented self-regulating, short-stroke gas-piston operating system, ensuring unparalleled reliability in the harshest theaters of operation. A side-mounted charging handle allows the shooter to perform reloads without removing their eyes from the target, and prevents any gas blowback to the face when using a suppressor. The ARM-R™ rails are easily removable and reinstalled with a hex key and provide a 100% return to zero for optics and lasers.

The R.E.P.R. rifle is available in three models: Standard Model (16.1") and Sniper Model (20"). The DMR and Sniper models will feature Geissele triggers. Each R.E.P.R. rifle comes with one barreled upper, but extra uppers are available in light contour 16.1" and heavy contour 20" configurations. Custom packages including one lower and two or more barreled uppers are available. These packages can be had with a variety of optics and accessories. Contact our customer service department for specifications.

New for 2012, we are offering the 16" R.E.P.R. with a spiral fluted barrel. The spiral fluting shaves weight while relieving longitudinal stresses that can cause 'stringing' in barrels with conventional linear fluting.

 

[rojodiablo]

From the web site .... I have shot about 120 rounds of the Federal 168gr BTHP ... no issues and the rifle is highly accurate! I have the 16.1" barrel ...

Caliber: 7.62 NATO/.308 Winchester
Barrel Length: 16.1", 20"
Weight (unloaded): 9.5lbs (16.1"), 11.25lbs (20")
Length (overall): 40.8" (16.1"), 41.5"(20")

Rifling: 1/10" RH; 1/11.25" RH (Optional)


The R.E.P.R. rifle utilizes our patented self-regulating, short-stroke gas-piston operating system, ensuring unparalleled reliability in the harshest theaters of operation. .

Okay, there is a difference there; the self-regulating gas system might mean non adjustable. Mine was adjustable with 4 positions, so you could run just about anything thru it.
As to barrel specs............ Other than the fluting, the barrel is the same as the BM, DPMS, S&W, etc. It's a 1/10 twist, as mine was. The barrel itself should be a non issue with regards to using multiple types of ammo.

LWRC makes some nice rifles. It's a shame they are so unaffordable.

 

[SeanYawn]

I recently finished building my M&P and have every ammo I have run through it has functioned flawlessly with the exception of cbc brand 7.62. This is ammo would fail after about 5-10 round then it would consistently ghost chamber after ejecting the brass. I oiled the hell out of the bcg and still was having issues stripping the next round. I can manually chamber a round after a ghost chamber, and the bcg would Not lock open with cbc after the last cartridge. I'm wondering if maybe it was a heavier round and I was running out of battery?


The rifle is new, and I have put about 250-300 rounds through it. No signs of carrier tilt, abnormal wear, etc. I was hoping someone here might have more information about tweaking the gas system? I am seeing crazy cheap amounts of that cbc and it would be nice to have more 7.62 food for my rifle.