First Outting with new M&P 10

[Sgt. PArnold]

Here is a pic of the rifle as I took it to the range. No mechanical changes were made. It was cleaned and lubed.

I purchased the rifle about two weeks ago, but it appears to have been manufactured in October 2013. It came with a GEN 1 PMAG (20 rds). I picked up three more GEN 3 PMAGS.

I installed a Millet DMR 1x4 to start with. I also installed a set of Troy iron sights.

I started out using Sieller & Bellot 150 grain FMJ. The first five rounds went without problems. Then the rifle "changed" into a single shot (short stroking) with mulitple failures.

Discouraged, I switched to the Federal Premium 168 grain MatchKing, the .308 "gold" standard. Fired 60 rounds without a single malfunction. Achieved one hole hits at 50 yards and consistent hits on the 10" gong at 75 yards . The rifle has accuracy potential.

First the ammo issue has to be fixed. I expect this beast to eat anything I can find to shove in a mag. A singular diet of 168 Match is not inline with my intended use for this rifle. I have others for that purpose.

I will be installing a free-float rail and lp gas block along with some other "adjustments".

I will post results as soon as completed. I noticed a new ad for the M&P 10 in American Rifleman and they listed the rifle as a ".308/7.62 x 51" caliber!!

 

[apiccola]

The tricky thing behind the S&W ad is whether or not "7.62x51" means "7.62x51 NATO" or "7.62 NATO". I have seen boxes of commercial ammo that read ".308 WIN/7.62x51mm", which were definitely not 7.62 NATO brass.

I even checked the ad for my LWRC REPR, and it specifically addresses "7.62 NATO". LaRue Tactical ads, however, do not mention either .308 Winchester or 7.62 NATO.

I do agree that Smith & Wesson needs to address this. A class action law suit for deceptive trades practices may be the ticket.

 

[apiccola]

Just found my M&P10 manual. Under the Ammunition section, it does specifically represent that the rifle can also fire 7.62x51 NATO.

As a first step, I recommend that everyone having problems with this ammo go to the Better Business Bureau website and submit a dispute with Smith & Wesson. When you submit the dispute, be sure to include your rifle serial number in the dispute.

 

[apiccola]

Also, if you do choose to submit a dispute through the BBB, you should note in the claim that Smith & Wesson states on page 10 of the Safety & Instruction manual that the M&P 10 rifle can also fire 7.62x51 NATO ammunition.

 

[Vermont]

Are there a lot of people having this issue with the 10? I'm just wondering because mine has been eating anything I have been able to find so far - XM80 LC 7.62 NATO, off the shelf .308 in a few different varieties, even some Israeli 7.62x51 IZI surplus with '83 headstamps. I'm new to this forum (and to this rifle) so sorry if this is a stupid question, just wondering if mine is the norm, or if I should expect trouble down the road.

 

[Veeper]

Wait so call BBB before you call S&W ???


Please excuse any whoopsies, I'm currently using Tapatalk.

 

[apiccola]

I'm assuming a good number of the folks that have cited the issue have already contacted S&W about the concern. There's a fellow on this board that said his rifle has been shipped for warranty repair at least twice for the issue with no resolution of the problem. And quite honestly, if a person anticipates a breach of warranty/trust by a corporation or they feel uncomfortable with their own capability to communicate with that corporation in order to assert their case, there is nothing wrong (legally or ethically) with contacting an advocate or an intermediary to communicate on their behalf and advise them whether they are being treated fairly or not.

 

[sgtsandman]

It may be an issue with your particular rifle. My first outing was with 7.62x51 NATO and if functioned just fine.

Just a few probing questions. Did you clean the weapon before you took it out to the range?

The reason I ask is, no matter what firearm I have purchased, they were dirty as heck out of the box and needed the factory gunk and dirt cleaned out of it.

Have you looked at your gas port and tube to make sure they are completely open?

The reason I ask this is because there may be a burr that is blocking the port or tube and this causing the short stroking. F.O.D. Issues happen sometimes during the manufacturing process.

Just a couple of things to consider.

 

[068]

I picked up a M&P 10 last Friday, topped it with a Nikon Buckmaster scope and shot it Monday afternoon. The only problem I had was when I tried to cycle the bolt, with a live round chambered, it took a pretty good amount of force to get it back. That only happened once though.

I didn't experience any of the magazine problems or any FTE/FTF problems.

I started out with Hornady 168 grain match ammo and the rifle performed flawlessly.

The 4 rounds to the right of the bullseye were during zeroing. The 3 in the red were after adjusting from the last shot and the string to left was just me shooting to get a feel for the rifle.

 

[copemech]

View attachment 147804

Here is a pic of the rifle as I took it to the range. No mechanical changes were made. It was cleaned and lubed.

I purchased the rifle about two weeks ago, but it appears to have been manufactured in October 2013. It came with a GEN 1 PMAG (20 rds). I picked up three more GEN 3 PMAGS.

I installed a Millet DMR 1x4 to start with. I also installed a set of Troy iron sights.

I started out using Sieller & Bellot 150 grain FMJ. The first five rounds went without problems. Then the rifle "changed" into a single shot (short stroking) with mulitple failures.

Discouraged, I switched to the Federal Premium 168 grain MatchKing, the .308 "gold" standard. Fired 60 rounds without a single malfunction. Achieved one hole hits at 50 yards and consistent hits on the 10" gong at 75 yards . The rifle has accuracy potential.

First the ammo issue has to be fixed. I expect this beast to eat anything I can find to shove in a mag. A singular diet of 168 Match is not inline with my intended use for this rifle. I have others for that purpose.

I will be installing a free-float rail and lp gas block along with some other "adjustments".

I will post results as soon as completed. I noticed a new ad for the M&P 10 in American Rifleman and they listed the rifle as a ".308/7.62 x 51" caliber!!

Good luck with that! Seems they will not run anything! They seem to like US brass! Your problem with the Siellar may be running TOO FAST causing bolt overs. How far did it eject?

Too many issues whth these guns. Gotta find and stick with what works or mod accordingly. PITA!

 

[Drag]

What some folks don't realize is that the 308 Winchester is a HOTTER round than the NATO 7.62x51. SAAMI rates the 308 Winchester at 62,000 psi vs only 50,000 psi for the NATO equivalent. Also, I've read in multiple places that it's safe to use 7.62x51 NATO ammunition in a rifle chambered for 308 Winchester. However, the reverse is not true given the the significant differences (>20%) in pressure limits. So it's comforting to know that the M&P10 is rated for the hotter 308 Winchester cartridge.

From 6mmbr.com:

Before we go much further, we want to address the oft-posed question "are the .308 Winchester and 7.62×51 NATO one and the same." The simple answer is no. There are differences in chamber specs and maximum pressures. The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62×51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630″ vs. 1.635″ for the 7.62×51. The .308′s "No-Go" dimension is 1.634″ vs. 1.6405″ for a 7.62×51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62×51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: "[N]obody makes 7.62mm (NATO) ammo that isn't to the .308 'headspace' dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule." You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62×51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max.

 

[MistWolf]

We know commercial 308 is hotter than 7.62 NATO. We also know that 7.62 NATO ammo pressures are all over the map. Some lots are hotter than others. It's also known that the 7.62 NATO chamber is longer which reduces the pressure of commercial ammo shot in it.

One fact that gets lost in the wash is how NATO & SAAMI measure pressure. If NATO measures the pressure of the 7.62 NATO the same way they measure 5.56 NATO, the pressure transducers used are different than SAAMI transducers and the location where the pressure is measured is also different so the pressure between the two cannot be directly compared.

All that said, anyone know of actual problems firing commercial 308 in rifles with 7.62 NATO spec chambers?

 

[sgtsandman]

You can get away with it for a while but like firing 5.56 in a barrel designed for .223, if the chamber doesn't burst on you, there will be accelerated wear in the chamber and the barrel. As a general rule, it is better to get the barrel for the hotter of the two rounds to get the most flexibility and and minimize the worry.

 

[copemech]

Yea well?

I have my own theories that it seems to me that many overlook. I am no expert. I go with what works, but at the same time I admit to being a bit disappointed in the guns flexibility.

Everyone likes affordable ammo, cheap steel, mil surp whatever 308 or 7.62 is out there. I do not necessarily expect accuracy out of it, but?

That has also been witnessed in my selections thus far, mainly w/ 150 gr from several sources.

Folks talk about pressures, yet I think ultimately the cycling of the gun comes down to exactly when these pressure peaks occur due to the burn rates of the powder.

US standard brass is ususally made with a powder set for a 24 inch long gun and burns at a rate set of max potential for the barrel.

The short window of opportunity to operate a gas gun lies in the distance between gas port opening and bullet exit of barrel.
If your pressure peak has occurred before that and spit the dummy (pistol powder) things have already declined, while on the other hand, with a rifle powder, pressures may be still building or more constant.

I am also questioning the fact that having high recoil and good ejection due to initial high pressures translates into good cycling which is too quick!

I have read elsewhere that an M-14 can be a pickey eater as well, so that fact makes me feel better. But I still wish the guns had a wider window without resorting to complex mods and adjustments.

My theories also dig into the spring rate equasion, and put simply a longer and smaller spring is going to change rates a smaller amount in a given distance of travel.

Would a rifle stock tube have advantage? Not with a spacer to use original spring and buffer, you are back to stock.

Adjustable gas port, yes it would work within its range of tuning.

Rambling now, still no solid solutions other than high priced ammo that works! Load your own!

 

[sgtsandman]

I haven't had mine too long and it's been winter, so shooting experiences haven't been plentiful. My rifle seems to run just fine with both .308 and 7.62. Maybe I'm just lucky...

 

[MistWolf]

You can get away with it for a while but like firing 5.56 in a barrel designed for .223, if the chamber doesn't burst on you, there will be accelerated wear in the chamber and the barrel. As a general rule, it is better to get the barrel for the hotter of the two rounds to get the most flexibility and and minimize the worry.

The only problem there will be shooting commercial ammo out of a NATO chamber is if the brass is weak and splits. Because the NATO chamber generally has a longer headspace than SAAMI chambers, the ammo will generate less pressure because case capacity becomes larger.

Not many rifles chambered for 7.62 NATO are available to civilian shooters because they are usually headspaced to 308 SAAMI specs

...The short window of opportunity to operate a gas gun lies in the distance between gas port opening and bullet exit of barrel...

...If your pressure peak has occurred before that and spit the dummy (pistol powder) things have already declined, while on the other hand, with a rifle powder, pressures may be still building or more constant...

Chamber pressures peak as the bullet first enters the rifling, then declines after that as the volume the gases are filling increases.

The time the bullet is in the barrel between the gas port and muzzle has little to do with how much gas enters the expansion chamber. That time is very short and the difference in time with a variation an inch or two is even less. Even so, if the expansion chamber were to fill while the bullet was still in the barrel, the distance would make no difference at all as the chamber would fill when the bullet was the same distance from the gas port, regardless of the distance from port to muzzle.

The gas travels down the gas tube to the carrier at a slower speed than the gas pushing the bullet. When the gas passes through the port, it drops to the speed of sound. It has further to travel from the port to the expansion chamber than the bullet has to travel from port to muzzle. The bullet and the gas pushing it are supersonic.

The bullet exits the muzzle and is several feet down range before the action (reciprocating mass) begins to move. This means the rifle is being powered by the residual gas pressure that's left after the bullet has uncorked the barrel. This is a good thing, because it means the pressure in the barrel has dropped to a safe level before the bolt begins to extract the case. It would be a bad thing if gas pressure in the range of thousands of PSI were vented into the atmosphere close to the shooter's face!

The distance from port to muzzle does matter. The longer the distance, the more time it take the gas to drop to ambient pressures at the port, because if the pressure were to drop too soon, the rifle wouldn't function.

The port does not control pressure, it controls flow. It controls how many cubic feet per minute will pass through the port at a known pressure. The port must be sized so the correct amount of gas can pass through it in a short enough time to operate the action. The further from the chamber, the lower the pressure. That's why a carbine gas system uses a smaller port diameter than a mid length gas system

 

[duggie76]

I apparently am part of the lucky few that have not had any problems. From 7.62 mil surplus to 147 grain pmc to **** herters steel I have had no issues. I would like recommendations of "bad ammo" so I can test it out. Otherwise my gun has been a champ, even with the ****ty 10 rd steel mag it shipped with.

Sent from my SCH-I605 using Tapatalk

 

[sgtsandman]

Mistwolf,

Interesting on the commercial ammo in a NATO chamber. I've never heard or run across a case problem because of it. You are correct on the the head space difference, so I suppose it is possible.

On the second quote, some how it was attributed to me and I don't think I typed that. It looks like copemech did. Weird.

 

[LASigmon]

So far I have only fed mine Fiocchi 308 150 grain and Lake City 7.62 NATO 149 grain with no problems at all. Accuracy was good with both.

 

[Bat Guano]

Thinking about an M&P 10 "just because".

Quite a few years' loading for and shooting various ARs, Garands, and M14s/M1As makes me wonder just what people are stuffing in these rifles. My experience with the foregoing was that given decent in-spec ammo and maintenance, reliability was outstanding.

My M1A always ran just fine with 41.0 gr. 4895 and the M80 FMJ 147gr. or the 168gr. SMKs.