Piston or DI for a Grendel Build?

[HuXXXford]

I'm looking to build a long distance rifle using the 6.5 G and a 20 or 24 inch AA barrel. I recently bought a new piston driven AR-15 and love it...mainly the ease of cleaning and how clean and cool the chamber and bolt remain.

I'm thinking however, for a rifle that I'd like to reach out and consistently hit its target very accurately over long distances, I should probably go with DI. My concern with running a piston driven system would be the reason some snipers still prefer a bolt action system...no moving parts to throw off the shot. My issue is, I'm not certain whether or not the extra movement would even be perceptible or enough to throw off a shot.

What do you all think?

Thanks,
Hux

[rkflorey]

I have played with Piston uppers in the past and really don't see the advantage for the additional money. I have only seen one DI gun that had issues with operation that could be traced to the gas system (broken gas key cap screw). If you just have to have one or like the easier cleaning then go for it. Otherwise spend the cash on an upgraded scope or trigger.
My 22" CSS Grendel is accurate and reliable. I would have no trouble trusting my life to it. Welcome and good luck with the build. Kevin

[Schwag173]

I agree with rkflorey. A friend of mine recently purchased piston ARs and kept asking my opinion. I finally asked him how often he had a stoppage when he was in the Marines (with direct-impingement M-16s). He hung his head a bit and replied 'never,' and this was firing a lot of ammo at one time, full-auto, etc. Piston systems are great because you can have side-folders for a really compact weapon and cleaning is much easier. But, so what? They are also heavier and the extra weight is out front where your support hand has to bear it. I'm not opposed to pistons, but there are definite trade-offs. I'm sticking with DI because I'm not firing thousands of rounds per day and I'm willing to clean my rifle. I've heard some on this forum claim that DI is inherently more accurate, but that is beyond my knowledge level. Personally, if I was going to build a 20-24" barreled rifle, I wouldn't want a folding-stock and since there is already a heavy barrel (especially if it was a bull) I wouldn't want the extra piston weight. So, there you go ...

[txgunner00]

DI all the way especially on a long range gun. A long barreled precision gun is not a machine gun, therefore there is no need for a piston system in the first place. Also, as you mentioned, adding moving parts to your barrel could be detrimental to accuracy. It certainly doesn't help it. Piston systems have their place and that's on full auto carbines or PDWs.

[montana]

I have converted many DI systems to gas pistons and have loved them for the reasons you stated. I would go with the DI system for your long range shooter to keep the weight and recoil down. If you have a gas problem I would look at the Syrac gas block which still uses the DI system. That being said, I have never had a accuracy problem with my piston gas systems.

[HuXXXford]

Thanks for the input, guys. I was leaning toward DI based on the points we've all made, but wanted to get additional input from other shooters and your experiences.

I mainly bought the Piston AR to add to my collection since I already have a couple DI ARs. However, after handling it, firing it with zero malfunctions, and cleaning it, the Piston AR is my new, go to gun. So after having such a great experience with the Piston AR, I certainly wanted to put the question out there with this build.

Keep it coming if anyone has anything else to add...

[noone]

Find out what types (DI or PISTON) of rifles are used at local matches, and how they run and/or win. I think you will find that the vast majority of these guns are DI rifles. When Stoner built the M16 DI rifle, he knew about pistons on Garands, M14's and other rifles. There were a number of very good reasons why he went DI rather than piston.

I guess while I find piston rifles interesting, and would keep one if it were a gift, if I were buying a rifle, I would buy a DI rifle for the following reasons:
1. While there is much standardization with the parts for DI rifles, that same interchangeability is lacking between all the various piston rifles. This means that if something goes wrong, parts will be harder to get, and probably more expensive.
2. If the piston rifle you buy gets taken out of production, getting parts can be a terrible chore.
3. Usually, DI rifles are more accurate than piston rifles. But, piston rifles are cleaner (I prefer accuracy to clean though)
4. In the above posting from the Marine who admitted that DI rifles work even when dirty, that solves much of the issue of
why I would need a piston rifle anyhow. Rifles are dirty, that is just the way it is...look at the HK roller locking system..
it is one of the most filthy systems in the world, but it sure works.

The bottom line for me is: Don't fix it if it works. All my DI rifles work just fine thanks. I see no need to change.

[rasp65]

My Grendel has a piston system in it. It is an ingenious design where the piston is inline with the bolt carrier so that it does not torque the rear of the carrier into the buffer tube. That guy Stoner was a brilliant designer, maybe that is why the rifle he designed has been in service so long.

[usmc1371]

i would stick to the di system. moving parts along the barrel do have effect on accuracy. we all know that the grendel is a very accurate round. if it aint broken dont fix it.

[dwalters66]

Well...FYI...I think the accuracy debate is more scholastic than real. Most modern gun makers making piston guns have compensated for the issues concerning this. But moreover, the Marines adopted the H&K417 and M27 which are piston stroke rifles.

[Mike Wood]

Holy 4.5 year old thread resurrection

[ahillock]

Holy 4.5 year old thread resurrection

Better than starting a new thread on the same topic. Better to add to the existing information and discussion. Date of thread has no barring on discussion. Rather have 3-5 threads on a topic but with great info consolidated than 15-20 with poor info.

[Mike Wood]

Better than starting a new thread on the same topic. Better to add to the existing information and discussion. Date of thread has no barring on discussion. Rather have 3-5 threads on a topic but with great info consolidated than 15-20 with poor info.

Cool

[Grendel]

Long range accuracy, DI operating system maybe better since the bullet has left the barrel before the carrier moves. Piston guns I'm not so sure the carrier isn't in motion before the bullet leaves the barrel.

[Grendel]

https://youtu.be/phwDMrau_7Y