Got into a discussion on another board recently about the MCX spear and why it was a 2.5 MOA gun. I commented that it's difficult to make a piston-driven gun shoot accurately. The other poster said not if it was designed that way.

I said okay, so show me...

He mentioned the 417 and the M110.

I know zip about either of those guns. Are they piston-driven and have they proven to be as accurate as M21 or a match-conditioned M14?

Do you see piston-driven semi-autos at the 600 or 1,000 yard line?

Asking sincerely as I can be in a M14 bubble and would like to know.

Tony.

I am not speaking from experience.

The M110 is not piston-driven.

I believe the Proof-barreled LWRC REPR has a reputation for accuracy. It is a piston gun.

quote:

I commented that it's difficult to make a piston-driven gun shoot accurately.

Why is that?
Curious.

I always attributed accuracy to: shooter, optics, trigger, barrel, ammo-load.

A while back I built a 20" AR with an Adams piston unit (yeah I know a rifle gas piston is kinda of dumb but it was an experiment), WOA SDM barrel, Gisselle Match Trigger and NF F1 Optics that shoots pretty dang good with GMM or my reloads.

quote:

Originally posted by KSGM:
I am not speaking from experience.

The M110 is not piston-driven.

Thats not exactly correct. While the M110 is KAC SR-25 (DI) variant, the M110A1 is an H&K 417 variant (Piston), the M110A1 are supposed to replace/have replaced the M110 (at least on the conventional side. The SR-25 and it's variants might still be in use on the SPF side. Neither rifle is considered a battle rifle, I can't get into FMSweb right now and verify the nomenclature, but IIRC the M110 is categorized as Semi Auto Sniper Rifle and the M110A1 is either the same or an SDMR depending on the document/optics configuration.

To Benny's question, that's a hard question. I'm not an M14/M1A fan, but Benny gets magnificent results with his rifles and regularly impresses me.

I would not compare a Match Grade/match conditioned M14 to a battle rifle. I'd compare it to other match or precision style rifles. For example, the SR-25, FN MK20, HK 417 precision models and the H&K PSG-1.

That said, based on the results Benny has posted over the years, Benny and his M14 would kick my ass with any of the above rifle.

Once my access is back I can take a look at the MIL-PERF on the M110 vs the M14s, but I don't think it's particularly relevent.

In the real world, I haven't seen a match level M14 shot, I have seen Ar-10 equivalents shot on man size targets out to 1K.

quote:

Originally posted by smschulz:

quote:

I commented that it's difficult to make a piston-driven gun shoot accurately.

Why is that?
Curious.

I always attributed accuracy to: shooter, optics, trigger, barrel, ammo-load.

A while back I built a 20" AR with an Adams piston unit (yeah I know a rifle gas piston is kinda of dumb but it was an experiment), WOA SDM barrel, Gisselle Match Trigger and NF F1 Optics that shoots pretty dang good with GMM or my reloads.

With a piston-driven platform, there are many more components attached to the barrel at different places.

With the M14, you have one full pound of steel hanging off the barrel, to include gas system and an operating rod.

The gas cylinder, front band, gas lock, gas piston and a gas plug hanging 3/4ths of the way down the barrel. The piston slides back and forth and slams into hard stops in both directions, sending vibrations throughout the barrel and the entire rifle. The M14's cycling is so violent that it has been known to destroy scopes of lesser quality due to the constant directional changes in recoil impulses. There are four rear recoil impulses (1-the actual recoil of the round going off, 2-the gas piston hitting its rear hard stop, 3-the bolt hitting the inside of the receiver heel and 4- the operating rod hitting the receiver face) and two forward recoil impulses (1-the bolt closing and 2- the operating rod and the gas piston hitting the forward hard stop). These impacts destroy scopes and shift the action around in the stock.

Then there's the operating rod which is hanging off the barrel via the operating rod guide. It moves under the barrel very quickly and rubs the barrel the entire way. It hits the receiver face when ejecting the round and moves forward until it slams the gas piston against its forward hard stop.

I just weighed the moving parts and they account for 9 ounces (over 1/2 a pound) of steel that moves under, and is directly in contact, with the barrel.

All piston driven systems have metal pieces contacting and moving under or over the barrel. This is typically very bad for accuracy.

The M14 design has had the advantage of armorers developing tried and true methods of negating the negative effects of a piston driven system for decades is the military's competition service rifle. Chassis systems have come along to tackle those issues as well.

What I don't know is if there is another piston driven system that has had improvements developed to enhance accuracy like the M14 has.

Can any other piston driven system be enhanced to match the M14's enhanced accuracy? That's the crux of my question.

Tony.

I would bet that pretty much any contemporary 308 will outclass even a tuned m14.

Top contenders with external piston:
LMT MARS-H piston
SCAR-20s
B&T APC 308
HK MR762

This message has been edited. Last edited by: JoshNC,

quote:

Can any other piston driven system be enhanced to match the M14's enhanced accuracy? That's the crux of my question

I like considering questions like this one, as is evident by some of the more absurd threads I often instigate, like the recent 7.62 versus 5.56 discussions. It's damn hard to come to definitive conclusions without expending tons of time and money on real comparative testing though.

I am sure there is oodles of accessible performance evaluations of accurized M14s and M1As, since they've been around for quite a while. These other, more modern, external long or short stroke piston rifles haven't had the same amount of time in caring, seemingly often civilian, hands.

Since I mentioned that LWRC, I looked around a bit online, trying to find someone who shared accuracy reports about it. I came up dry.

The guns JoshNC mentioned are all likely candidates, and I am sure there's some findable statements about accuracy. Statements aren't the proof we're wanting, to answer a question like yours though. Sometimes the guns do better than military solicitation accuracy goals, but often they don't.

I am no expert, but I do believe that the proof is in the real targets. Fritz has proven to be a motivational stickler for me. Thanks to him and people like sigfreund, I have proven the accuracy of my Colt 901 out to 300M. It's right at 1MOA, which is pretty good, IMO, for a gas gun, from a largely practical shooting position. The 901 is not an external piston gun.

I think, due to the lack of thorough documented evaluation of contemporary options, outside of questionable military solicitation testing documents, the answer to the M14 versus the rest question is perhaps unattainable.

It's fun to speculate though. I, for one, think that there's no reason why a current production external piston rifle built for accuracy couldn't out-perform an M14 built for accuracy. The foundation being more modern, and applying more lessons-learned (thanks, no doubt, in large part to the M14) seems to be a guarantee of better outcomes.

I am no expert though. My opinions expressed above are based on my arguably limited shooting experience, discussions with members here, and research online.

The SCAR MK20, the LMT MARS-H, and the 417 precision models are probably the ones to dig into. SR25 and PSG-1 would be out of contention, due to a lack of external piston.

I tend to see more inline gas traditional SR25 type rifles shot for precision at our range and amongst my friends. We have steel out to 1200 yds. KAC, LMT, Seekins are among the most common. We got a number of Seekins SP10 6.5cm in and they are laser beams with excellent features.

A gas piston truly buys you nothing at all when considering a DMR type 308 or 6.5cm gas gun. If given the choice, I’d personally choose the inline gas system over a piston in a Stoner pattern gas gun being shot for precision.

The M14 is an interesting rifle from a historical standpoint, but it’s totally outclassed by the contemporary SR25 pattern gas gun in terms of modularity, repeatability, ease of maintenance, optic mounting, accessory mounting, etc.

Among friends who have been issued both the m14 in a Sage chassis and an SR25, every single one has said he would grab the SR25 over the M14. And not a one had good things to say about the M14 for contemporary uses.

Look at the SCAR 17S or 20S. Short-stroke piston. They are known to be quite accurate with good ammo. But "as accurate as a match-conditioned M14" is a subjective metric. what kind of accuracy are we talking here?

I think the question is: can a modern "cutting edge" external piston 7.62x51 rifle be made to be more accurate than an accurized M14?

The question doesn't involve SR25 rifles.

From your other thread it looks like you are getting about 1.3" 5-shot group at 100 yards with your hand loads.

My SCAR 17S with the factory 16" barrel will shoot groups like that with good match ammo. And while I don't own a SCAR 20S, there are plenty of reviews out there showing it shooting sub 1" 5-shot groups at 100 yards. So yes, some piston guns can meet that accuracy standard or better.

https://gundigest.com/gun-revi...of-the-box-precision

I would say a reasonable range for a match tuned M14 is .5 MOA to 1.5MOA, or simply an average of 1 MOA. This would be a true M14 DMR, EBR or a M25.

I recently installed and chambered a heavy Kreiger for a high power shooter in Washington. He finished the build and bedded it himself. He recently sent me this message…

Hope all is well with you down in sunny Florida! Just wanted to drop you a note regarding that barrel you chambered for me….I couldn’t be happier with how it is working!
I’m guessing you saw some of the accuracy posts I made and I’m confident this is truly a sub MOA (probably.8 to .9) for even a 10 round group. More important, the mean radius is probably in the .3 MOA class. Just super pleased with that.
One note for anyone considering that chamber, it is tight in the body of the case. I had to buy a small base re-sizer to get reloads to run. Even the brass fired in that chamber has to get the small base resize. I’m totally fine with that for the purpose of this rifle. It will be interesting to see how this throat geometry wears over the life of the gun.
Anyway, thanks again!

Here are his 600 and 1,000 yard range reports

https://www.m14forum.com/threa...1000.541672/#replies

https://www.m14forum.com/threa...4945173#post-4945173

My best shooting M14’s are 1/2 to .75 MOA rifles, and that’s for a 5 round group.

The rifle I posted earlier is a 6.5 that I’m still tweaking and learning. My last range trip was producing very good groups out of that barrel.

The Marine Corps Rifle team's acceptance criteria for a match rifle was anything under 1.5 MOA with the average rifle shooting .75 to 1.25 MOA.

I’ve built numerous match rifles for customers that fell in the same size range.

Tony.

quote:

Originally posted by benny6:
I would say a reasonable range for a match tuned M14 is .5 MOA to 1.5MOA, or simply an average of 1 MOA. This would be a true M14 DMR, EBR or a M25.

I recently installed and chambered a heavy Kreiger for a high power shooter in Washington. He finished the build and bedded it himself. He recently sent me this message…

Hope all is well with you down in sunny Florida! Just wanted to drop you a note regarding that barrel you chambered for me….I couldn’t be happier with how it is working!
I’m guessing you saw some of the accuracy posts I made and I’m confident this is truly a sub MOA (probably.8 to .9) for even a 10 round group. More important, the mean radius is probably in the .3 MOA class. Just super pleased with that.
One note for anyone considering that chamber, it is tight in the body of the case. I had to buy a small base re-sizer to get reloads to run. Even the brass fired in that chamber has to get the small base resize. I’m totally fine with that for the purpose of this rifle. It will be interesting to see how this throat geometry wears over the life of the gun.
Anyway, thanks again!

Here are his 600 and 1,000 yard range reports

https://www.m14forum.com/threa...1000.541672/#replies

https://www.m14forum.com/threa...4945173#post-4945173

My best shooting M14’s are 1/2 to .75 MOA rifles, and that’s for a 5 round group.

The rifle I posted earlier is a 6.5 that I’m still tweaking and learning. My last range trip was producing very good groups out of that barrel.

The Marine Corps Rifle team's acceptance criteria for a match rifle was anything under 1.5 MOA with the average rifle shooting .75 to 1.25 MOA.

I’ve built numerous match rifles for customers that fell in the same size range.

Tony.

Very nice. In your experience with the M14, if you strip the rifle to clean it, how is your zero affected upon reassembly?

Josh, I think you're fishing for reasons something of the modern external piston variety would be preferred over the M14, even if accuracy is the same or inferior to the M14. I am sure there are a few.

However, they don't change the crux of benny6' question: which is more accurate?

quote:

Originally posted by KSGM:
I came up dry.

I’ve found that over and over in my quests for information about the accuracy (okay, precision) of various firearms and ammunition.

The problem with answering the original question is all the variables that appear even in the large number of Internet videos about shooting more or less precision rifles. In addition to the rifles themselves, it’s ammunition: factory, handloaded, manufacturer, bullet type, general quality; sights: does the magnification permit accurate aiming; shooter skill: it’s obvious that many testers don’t really know what they doing all that well; shooting positions and rests: bipods, flimsy or rigid benches, types of rests; targets: if paper, are they properly designed (rarely) to permit accurate, repeatable aiming, and if they’re steel gongs at some convenient range, how does that permit valid comparisons with proper group shooting; number and sizes of shot groups; weather conditions; etc., etc., etc.

When good, valid comparisons of the inherent capabilities of various rifles and systems are impossible even with countless posts on the Internet, how can we expect anything better by hanging out at the local range?

quote:

Originally posted by JoshNC:

Very nice. In your experience with the M14, if you strip the rifle to clean it, how is your zero affected upon reassembly?

For a no lug M14, 10 to 20 rounds to resettle and return to zero. For rear lug and double lug rifles a torque screw(s), there should be no effect.

Tony.

quote:

Originally posted by KSGM:
Josh, I think you're fishing for reasons something of the modern external piston variety would be preferred over the M14, even if accuracy is the same or inferior to the M14. I am sure there are a few.

However, they don't change the crux of benny6' question: which is more accurate?

Absolutely no fishing needed. I would venture to say that all of the above mentioned external piston rifles will shoot the appropriate match ammo to the same or better precision and accuracy of a tuned M14.

The M14 is a neat rifle. So are restomod 60s muscle cars. And just like a restomod 60s muscle car being completely outperformed by a modern production sports car, the M14 is outclassed by contemporary rifles based on the sum of the important characteristics. I love the G3 too. They can be made very accurate and precise. Just like a M14, they are still outclassed by a SCAR20s, SR25 APC, LMT MARS-H, and HK mr762 when considering all attributes.

quote:

Originally posted by benny6:

For a no lug M14, 10 to 20 rounds to resettle and return to zero. For rear lug and double lug rifles a torque screw(s), there should be no effect.

Tony.

Interesting. Thanks. So what do you make of the reports by SOF that the M14 EBR in a Sage had such significant wandering zero issues any time they were stripped for cleaning? Old, worn out rifles that lacked rear/double lug? Operator error? My friends who speak of their experience with the EBR during deployment are not the operator error types and are great shooters. None felt confident in its ability to maintain zero. Ash Hess speaks of it regularly when interviewed on podcasts.

I managed to find mention of the accuracy of the HK 417 M110A1 CSASS. It was said by an HK employee that the accuracy of a new one is .44 AMR (average mean radius), over three 10rd groups at 100Y. So, I guess that's about .88 MOA. When accuracy is again tested, somewhere around twenty thousand rounds, it opens up to .60 AMR.

It's in this video, at 39:00.

quote:

Originally posted by JoshNC:

quote:

Originally posted by benny6:
I would say a reasonable range for a match tuned M14 is .5 MOA to 1.5MOA, or simply an average of 1 MOA. This would be a true M14 DMR, EBR or a M25.

I recently installed and chambered a heavy Kreiger for a high power shooter in Washington. He finished the build and bedded it himself. He recently sent me this message…

Hope all is well with you down in sunny Florida! Just wanted to drop you a note regarding that barrel you chambered for me….I couldn’t be happier with how it is working!
I’m guessing you saw some of the accuracy posts I made and I’m confident this is truly a sub MOA (probably.8 to .9) for even a 10 round group. More important, the mean radius is probably in the .3 MOA class. Just super pleased with that.
One note for anyone considering that chamber, it is tight in the body of the case. I had to buy a small base re-sizer to get reloads to run. Even the brass fired in that chamber has to get the small base resize. I’m totally fine with that for the purpose of this rifle. It will be interesting to see how this throat geometry wears over the life of the gun.
Anyway, thanks again!

Here are his 600 and 1,000 yard range reports

https://www.m14forum.com/threa...1000.541672/#replies

https://www.m14forum.com/threa...4945173#post-4945173

My best shooting M14’s are 1/2 to .75 MOA rifles, and that’s for a 5 round group.

The rifle I posted earlier is a 6.5 that I’m still tweaking and learning. My last range trip was producing very good groups out of that barrel.

The Marine Corps Rifle team's acceptance criteria for a match rifle was anything under 1.5 MOA with the average rifle shooting .75 to 1.25 MOA.

I’ve built numerous match rifles for customers that fell in the same size range.

Tony.

Very nice. In your experience with the M14, if you strip the rifle to clean it, how is your zero affected upon reassembly?

from what I remember, when I was shooting high power years at (with an AR) the guys that still had State Team M14's (yes, M14's , match prepped, were available for State Teams via CMP/DCM) they never broke them down to strip,
tools were available to clean the gas system, with out disturing it much, as well as a bore cleaning ritual (rifle upside down to keep fluids off the bedding)

I seem to recall, but it has been years, that soem would strip the rifle at the end of the season, clean, lube, gage and when put back together a skim coat of bedding was used to keep ti tight,

but it has been 20+ yrs, maybe 25, since I have seen a Team M14