Direct impingement vs individual carbine

Joined
Apr 1, 2017
Messages
551
Location
Grand Rapids, MN
Can anyone tell me the difference and pros and cons to these systems? New to ar and found a rifle I like but the company has both styles and didn't know there was a difference. Is this kinda like an inertia vs gas operated shotgun? Or not even close?
 
Joined
Jun 21, 2019
Messages
2,555
Location
Missouri
Do you mean direct impingement vs. piston-driven? I'm not familiar with the term "individual carbine," but it has been a few years since I built my last AR and I've forgotten a lot of what I read when doing my pre-build research. Someone else will likely come along with more expertise on the matter, but assuming that you're asking about the different methods of cycling the gun, here's what I do remember:
Direct impingement is the typical method of cycling an AR and routes exhaust gas from a port in the barrel directly into the bolt carrier group. A piston-drive mechanism adds an extra link in the chain between the barrel port and the BCG: exhaust gas drives a piston and the piston drives the BCG. Piston-drive prevents exhaust gas from entering the BCG and therefore keeps the action cleaner and reduces fouling. The downsides of piston-drive are the extra cost and possible sluggish cycling (though I think the latter is largely a non-issue because most AR's are "over gassed" to start with).
 

sndmn11

"DADDY"
Joined
Mar 28, 2017
Messages
10,419
Location
Morrison, Colorado
If you are talking about the LWRCI rifles, I would only get a DI version simply to avoid proprietary parts. Colt, BCM, Daniel Defense would be good choices in that price range, Aero if you want to get two for that price.
 
Joined
Sep 7, 2018
Messages
1,207
Location
Pennsylvania
Here's a hard truth, with proper lubrication even a dirty direct impingement AR will be reliable if it's a quality gun. Piston driven is 100% unnecessary.
 

PredatorX

WKR
Joined
Aug 16, 2015
Messages
797
Piston runs cleaner no matter if running suppressed or not. DI poops where it eats. However, for civilian use I wouldn't worry about it and get DI for the simplicity of parts and commonality. Just need to scrub the bolt carrier more often.

Sent from my Pixel 4 XL using Tapatalk
 

Njpddet

FNG
Joined
Aug 14, 2020
Messages
2
My LWRC runs much, much, much, cleaner than DI guns. Interestingly, our Sig duty rifles ran much dirtier than the LWRC (but cleaner than DI rifles)


Sent from my iPad using Tapatalk
 

FLS

WKR
Joined
May 11, 2019
Messages
826
How much cleaner? I still get a lot of carbon back through the barrel due to the suppressor.
My piston rifle is significantly cleaner than my DI rifle is. Properly lubed and maintained I can’t say one is any more reliable than the other. I’ve used both in some high volume 3 gun and carbine matches, and with good ammo and mags neither has ever let me down.
 
Last edited:

Rockwell

FNG
Joined
Sep 12, 2020
Messages
53
Many find the DI system to be more consistently accurate than piston driven guns, DI guns typically are slightly lighter in weight, balance better and were costing way less than the other. Then there is the proprietary parts thing that you add into the equation. Personally I careless about the cleanliness of the system as most DI's will get it done reliably.

Not all piston systems are created equal, stick with the one or two top brands and you should be good or be ready for carrier tilt issues and broken rods in your future.
 

USMC-40

WKR
Joined
Nov 22, 2016
Messages
564
Location
NW Missouri
I have exclusively owned DI guns, although I have had the opportunity to shoot several piston variants. DI works great, suppressed, unsuppressed, whatever, as long as its a quality rifle and moderately maintained. My issue with piston guns is there is no 'standard' to which they are made (i.e. the TDP for mil issued M4's). So obtaining spare parts, or heaven forbid a manufacturer discontinues support for a proprietary system (see almost everything Sig has made) then you have a cool looking paperweight. With my DI guns I can swap around BCG's and almost anything else if an issue arises.
 

Marbles

WKR
Classified Approved
Joined
May 16, 2020
Messages
4,469
Location
AK
A good DI system will run without TLC.

Edit: the link I posted does not work. Google 'BCM Filthy 14.'

Get the DI, it can be converted to piston latter if you want. Not all piston systems can be converted to DI.
 
Joined
Apr 8, 2019
Messages
1,975
I have both but DI will work for 95% of the applications needed. Pistons that let you adjust the gas flow are nice for SBR with a can. But like others have said if you get that far down the road you can convert DI to piston.
 
OP
skyler_2010
Joined
Apr 1, 2017
Messages
551
Location
Grand Rapids, MN
Thanks guys I was talking about lwrc rifles. The price at the gun shop was $600 less than the website so I'm gonna be putting it on layaway till I can pay it off. Thanks for the input I really appreciate it!
 

Rail505

FNG
Joined
Feb 9, 2020
Messages
54
Not sure if it has been mentioned.
Usually piston driven AR’s will weigh a couple pounds more that a DI counterpart. And all that extra weight is at the front. So holding a piston AR at the ready is much more tiring. I had the M6IC. Only thing i didnt like was that the rail was proprietary. Couldn't swap to an mlok rail to save weight up front. Sold it and now im deciding between piston or di again. Either LWRC M6A5 or Barrett Rec7.

Side note: if this will be a self defense gun, buy a factory made AR.
Built AR’s are fun, but they are just that, a range toy in my opinion.
 
Joined
Dec 27, 2012
Messages
5,217
Location
Colorado
Built AR’s are fun, but they are just that, a range toy in my opinion.

Tell that to the folks in the Armed Forces.....
 

Marbles

WKR
Classified Approved
Joined
May 16, 2020
Messages
4,469
Location
AK
Built AR’s are fun, but they are just that, a range toy in my opinion.

Depends on how they are built and the factory guns you are talking about. LMT, Colt, BCM or the high end custom makers sure. Personally I would not bet my life or the life of a team member on a Ruger, PSA, S&W, RRA, Etc., if given a choice.

Too many people and makers focus on bling (pic rails) rather than guts (properly staked gas key).
 
Top