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Discussion Starter · #1 ·
So I have recently purchased a 10.5 LMT Defender and while in the process of debating on what rifle to get my wife I had the chance to get a super smoking deal on a 12~" MRP piston.

A friend of mine bought one and noticed the op-rod had a slight bend to it. He called LMT to talk to them about it and they said "thats Normal" well I say "F$%&#^&" wrong answer!!! for the price of these rifles the op-rod better be straight.

For those guys who thought that short stroke piston ar's didn't have structural issues with the high gas pressure, and quick impulse pistons there is your answer. Do a search on the web for LMT's piston having a bent op-rod, some are worse then others.
 

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Aussie and I both just bought LMT (12") MRP uppers. No issues to report - but what should I be looking for as symptoms?

For the price, they had better be 100%!
 

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Discussion Starter · #3 ·
Aussie and I both just bought LMT (12") MRP uppers. No issues to report - but what should I be looking for as symptoms?

For the price, they had better be 100%!
Remove the gas plug and remove the op-rod (slide the spring off) then just roll it along a flat surface. I haven't heard of any failures but the bent op-rod made me go plain DI.
 

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you think the bending could get progressively worse where it would cease to work?
 

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you think the bending could get progressively worse where it would cease to work?
I don't know how likely it would be in that particular case, but once the forces applied are off axis with the rod because it is bent, it could potentially break. Or at least get to the point where it would interfere with function.

I would certainly expect better from a high $$ rifle.



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I guess I am fortunate, in that I inspected the op rod upon initial disassembly / familiarization and cleaning. Although I did not roll it on a flat surface, I believe it was indeed straight and true (and is still that way). If I encounter any subsequent deformity - LMT will be the first to hear of it!

Which forums are reporting problems? I haven't found any solid gripes (not that I searched a lot) - but I'd like to see some pics of issues if there are any out there.

Thanks!
 

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Discussion Starter · #7 ·
I was in the process of buying the 12" MRP piston when my buddy was all pissed about the one he had just bought. I asked what was up and he showed me some pics online of some guys that was obviously bent. When we checked his it was almost straight.

I am not sure if it will be a reliability issue over time but I sure as hell want a straight op-rod period.
 

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Discussion Starter · #9 ·
Looks like it'll be POF or LWRC for me if I go the piston route.
That said I think I would still get the MRP over the LWRC. I am up in the air on the POF's.

1.) LWRC piston a pain to take apart.
2.) PRICE, the lwrc is a relatively normal piston AR with a rail and is the same price as the MRP piston.
 

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Discussion Starter · #10 ·
Ok so after calming down about the price of a rifle with a warped op-rod I couldn't handle it anymore and purchased the 12" MRP Piston.
 

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I am completely happy with mine. What lower are you putting it on? I used my LMT lower that previously hosted my 10.5" A3 upper that is now seeking a home, possibly on a POF I have yet to build - but registered on a Form 1 as a 7.5" SBR.

Also, like the XCR, I believe you'll need to use premium ammo for the break-in period. Wolf did not work for either me or Aussie for out of the box initial firing. Low(er) power Wolf ammo did not cycle the action fully - resulting in FTF (either ejecting and not picking up another round - or ejecting and FTF the next round fully). However (as Aussie will confirm) when using a suppressor - there is PLENTY of back pressure to cycle the action even with Wolf.

My 12" MRP kit came with a nice 3/8" drive (preset) torque wrench and torx bit socket as well as replacement buffer with heavier bumper and a nice set of Magpul rail covers.

It took almost six months for them to fill our order, but is really a nice setup.

Post pics when you have 'er built!
 

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Ok so after calming down about the price of a rifle with a warped op-rod I couldn't handle it anymore and purchased the 12" MRP Piston.
You working tomorrow. I want to come by and check out the new toy.

Though...you really should have gotten the LWRC :p
 

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Discussion Starter · #13 ·
Ok so after calming down about the price of a rifle with a warped op-rod I couldn't handle it anymore and purchased the 12" MRP Piston.
You working tomorrow. I want to come by and check out the new toy.

Though...you really should have gotten the LWRC :p
I liked the LWRC but since it is a piston gun with someone else's rail that cost's as much as an MRP piston it was an easy choice for me.

I am working tonight.
 
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