Need Info on Piston AR-15 Uppers

[SirIsaacNewton]

Hey everyone was looking for info on piston AR-15 uppers. There seems to be a large selection now and I was wondering if anyone had any personal experience with any of these uppers and/or some suggested reading material.

 

[Obey]

I did my research and settled on the LMT:

Have a look at this:

http://www.defensereview.com/l...d-head-to-head-test/

I chose the LMT after looking at the POF and LWRC, and it seemed like, while newer, the LMT is a simpler design than either of those options. The strength of LMT's DI guns also helped me decide: if the piston guns are anything like their DI brethren, they will be rock-solid. The LMT is disgustingly well built, and the SOPMOD stock that comes along with it is nice. LMT is a government contractor as well, which is another plus.

 

[vsound]

My competition rifle is a POF piston upper, but I customized it a fair amount. I've got several thousand rounds through it, and it's only had one hiccup, but that was magazine related. With quality ammo it is sub-moa. Even with XM193 it is still probably 2-2.5 moa. It does have a little more kick to it than a DI gun, but with a comp on the front it is still less than a DI with a flash hider.

You may also want to look at the Adams Arms kits. You can get a standard DI gun and send it to them to turn it into a piston. That would give you more flexibility to customize your configuration.

 

[spanky]

I hear they significantly reduce the felt recoil of the .223.

 

[aroundlsu]

I went with the POF. The first thing everyone says about it is how heavy it is, though I don't really have anything to compare it to so I don't know the difference. Chris Costa spent most of the night last night at dinner telling us how often he sees POF's permanently fail in his classes. I am considering replacing it with a LWRC which he recommends.

 

[aroundlsu]

I hear they significantly reduce the felt recoil of the .223.

Yeah I heard the same thing from a very reliable source.

 

[vsound]

Did Chris say what kind of failures he was seeing?
I've read that POF seems to be letting their quality slip lately, but if you get one that works from the get go, they don't seem to fail much.

LWRC is nice too, but they are more expensive. I debated back and forth about doing a LWRC or a POF, and finally went with the POF based on how I wanted to customize it. The LWRC would have cost me a good bit more to get it to where I have it now.

Oh, and no, the recoil is not reduced. It is different and it is manageable, but it doesn't reduce it.

 

[dwr461]

A 223 needs recoil reduction? Buy a good quality muzzle brake for a heck of a lot less money than gas piston kit.


Dave

 

[SirIsaacNewton]

I am pretty sure they were being sarcastic with the recoil reduction statements. I wanted to understand the varying differences between the piston systems. Was not interested in reducing recoil. The interesting thing about the direct impingement is that the gas surrounds and then forces the bolt carrier group back. Does this apply even force all the way around the bolt carrier group? With the piston system it seems that all of them use a piston and a rod which strikes a plate at the top of the bolt carrier group causing there to be a force driving the bolt carrier up in the front and downward in the back?

 

[thatwhichisnt]

Spikes Tactical has one. Can't vouch for it, but all of their other products are quality.

 

[Tulse Luper]

Chris Costa spent most of the night last night at dinner telling us how often he sees POF's permanently fail in his classes. I am considering replacing it with a LWRC which he recommends.

Did he have anything in general to say about pistons?

 

[SirIsaacNewton]

Did he have anything in general to say about pistons?

What about the Robinson XCR? It looks like an AK/AR-15 hybrid it is really interesting. I would like to hear someone talk about this thing.

 

[aroundlsu]

Yeah he said he saw failures across the board with the pof. Nothing specific. Just general failures. He said he will not allow a pof with a suppressor on his range because he saw one blow up. So I am glad I didn't take the class. I would have been upset if I was not allowed to run my suppressor.

 

[Obey]

I am pretty sure they were being sarcastic with the recoil reduction statements. I wanted to understand the varying differences between the piston systems. Was not interested in reducing recoil. The interesting thing about the direct impingement is that the gas surrounds and then forces the bolt carrier group back. Does this apply even force all the way around the bolt carrier group? With the piston system it seems that all of them use a piston and a rod which strikes a plate at the top of the bolt carrier group causing there to be a force driving the bolt carrier up in the front and downward in the back?

You are referring to carrier tilt. I've posted the below on several forums, though its been a few months since I've looked into the issue, and I may need to update. In any case, I've never had a carrier tilt issue with my LMT and further, I hear the LWRCs have no carrier tilt, either.

RE: Carrier tilt, it seems like most LMT users report light to no carrier tilt marks in the buffer tube:

None after 2k rounds:
http://www.ar15.com/forums/top...l?b=3&f=118&t=445827

Light marks ("It does not seem bad at all"):
http://www.weaponevolution.com...showthread.php?t=786

LMT extension after 2k rounds:

(http://www.ar15.com/forums/topic.html?b=3&f=118&t=445827)

[As an aside, that gray stuff inside the buffer tube is some kind of dry lube that LMT puts inside the guns and buffer tube. It can be removed with an abrasive dish-sponge and some elbow grease, so that picture doesn't seem to indicate significant wear to me...]

...

It appears that most drop-in kits (ARES, AA, etc.) lead to a significant amount of tilt, though.

 

[Obey]

What about the Robinson XCR? It looks like an AK/AR-15 hybrid it is really interesting. I would like to hear someone talk about this thing.

I had an XCR for about 2 years. I liked it alot, and never had an issue, but I was concerned with the issues that others were having with the rifles. On one hand, you want to reward a company like Robinson for running a forum and answering issues as they crop up on their website. On the other hand, it is kind of the equivalent of "airing one's dirty laundry," and it exposes a lot of potential issues. The biggest issue is that you have to lock-tite the ejector periodically, and some have reported issues with it working loose. Robinson, however, now gives you the option to stake the ejector in a new rifle. I sold my XCR, even though I had about 3k rounds through it with no issues, simply based on what I had read. I was disappointed for doing so, but I couldn't shake the "what ifs" in the back of my mind. Also, I think the fact that the barrel is secured only by one downward-facing allen screw is a potential problem. Again, some reported that screw coming loose.

I think, once the XCRs little issues are resolved (which may have happened already) it is going to be a solid platform, if not the most solid.