Do LMT Piston guns suffer from the carrier tilt problem?

[Apollo11]

I have read mixed things about the tilt on the BCG, just woundering if the LMT's have this issue; and if it is a major problem with piston driven guns?


Thank you for the help.

[strambo]

I have an LMT Piston, but unfortunately I haven't put enough rounds through it ( only 50) to give any 1st hand info based on round count and can't anytime soon as I'm deployed overseas.

However, since I spent $1400.00 for the upper I had a keen interest in such topics and researched it relentlessly for a few weeks.

1. The Carrier has skids on the back with a beveled edge to address tilt. This mitigates rec. extension wear and limits the tilt enough (one would hope) that uneven stress on the bolt is mitigated as well and the cam pin can't/doesn't cause undue wear inside the receiver.

2. The Carrier has a one piece protrusion for the op rod to hit so it won't shear off. (nothing to do with tilt, just addresses another weak area in a conversion)

3. All reports and photos to date I've seen in guns with and without any skids on the rear of the bolt just show finish wear in the receiver extension (a lot less in guns with skids). All are functional, I've never heard of any failures or rec. extensions getting worn out. I've never heard of any bolts shearing due to off-center loads or premature failures, the closest was reports that Mil users are only getting about 12K out of their bolts in HK416's...which isn't the advertised 20K, but still a little better than in DI M4s.

I'm not worried at all. As I shoot it when I get back, I'll keep an eye on it. The receiver extension doesn't concern me in the least. I'm gonna pay special attention to inside the receiver itself where the cam pin is as well as the bolt. If I don't see excessive wear problems in those locations...there is no problem. If I do start to see excessive wear...I'll send the piston part back to LMT and swap in a DI barrel/BCG and learn a valuable lesson about jumping on the latest/greatest bandwagon.

There was a great write up about an LMT MRP Piston vs HK416 with about 2000 rounds downrange. No excessive wear problems. Same with the Ruger SR556 that was reviewed in the latest issue of SWAT which went through 2500 rds total and about 2000 in 2 days.

It will be interesting to see if the "tilt" issue crops up in real world application as opposed to being a theoretical problem. Pat Rogers' students put 10's of thousands of rounds through piston guns with no tilt issues.

Bottom line: If the mean # of rounds to failure attributable to piston parts/design is the same or better than a DI gun, the piston system and tilt can't be a "problem" just maybe not better, or better enough to justify increased cost/weight based solely on parts failure rates alone. The are other advantages (and disadvantages) to consider as well.

Also, of course, if a piston design failure is the receiver itself getting ruined, even at 20,000 rds...that would be a BIG Drawback over a DI gun even though it went 20K before failure!!

If anyone can post data about tilt causing problems/parts failures, especially in piston designs with the rear skids on the BCG, I would love to see it as well.

[Robb Jensen]

I have read mixed things about the tilt on the BCG, just woundering if the LMT's have this issue; and if it is a major problem with piston driven guns?


Thank you for the help.

LMTs will still leave marks in the lower receiver extension. It gets up to a point and seems to stop. For best reliability I highly recommend using a FRS anti tilt buffer with any piston AR. ARs are designed to have the carrier move in a straight line (linear) to the rear. Piston guns don't move this way even with anti-tilt pads or enlarged ends on the carriers. The FRS buffer addresses this problem better than any other design.

[Apollo11]

Thanks to you both, really helpful information. I have been reading through the threads from when the piston was released, and, like I said; I was still a little confused. I will look into the anti-tilt buffer as well.

Strambo, I would love to hear about your gun when you get back. Stay safe, and thanks.

I guess the main issues with this gun at first was the gas hole for the piston, looks like that has been fixed. Hopefully the tilt thing stays away.

[tusk212]

LMTs will still leave marks in the lower receiver extension. It gets up to a point and seems to stop. For best reliability I highly recommend using a FRS anti tilt buffer with any piston AR. ARs are designed to have the carrier move in a straight line (linear) to the rear. Piston guns don't move this way even with anti-tilt pads or enlarged ends on the carriers. The FRS buffer addresses this problem better than any other design.
Where does one find a FRS anti tilt buffer?

[Tokarev]

This looks like it might be an interesting method for dealing with carrier tilt.

http://primaryweapons.com/store/pc/viewPrd.asp?idproduct=139&idcategory=4

[unoactu]

Hello, I just recently purchased the Ruger SR556. I went to range and performed a barrel break-in which consists of 60 rounds. After break-in and upon cleaning I observed aluminum debris in the lower receiver and discovered wear damage to my buffer tube. See photos 1 & 2

I decided to purchase a MilSpec replacement tube and do a little custom work. I wanted to get 1 full turn past the original stopping point of the tube against the buffer retaining pin. To do this I had to do a little grinding and fitting. I screwed in my new tube where I wanted it to fit. I marked the spot for the retaining pin and the overage on the top & sides of the tube. Then I started work with my Dremel. See photos 2 & 3

I took my time here. Aluminum comes off quickly and I didn't want to over to it. I did a little and tried it, then did a little and tried, and so on till I achieved what I needed. See photo 4

NOTE: This is part one of my post, part two follow.

[unoactu]

Part two continued.

Photos 5 & 6 show my tube completed from the top & side view.

Photos 7 & 8 show the tube fitted in the receiver.

While I was at it, I wanted to take off the sharp edges from my carrier which assisted in cutting in my old buffer tube. The edges were sharp. I knocked them down with a file and very light grit sandpaper. See photo 9

I took off for range again to see if I had done any good. I slowed fired and rapid fired 80 rounds. To my amazement I never had any tube damage! See photo 10

Originally, my plan was to do the above procedure and pick up a Seth Harness buffer for good measure. I'm going to hold off a little bit now and see how it holds up with this set up.

I had to share this because I know how aggravating it is to spend a lot of money on something that doesn't work quite like it should.

[Jay Cunningham]

Pretty cool.

Have you seen the new PWS tube?

http://www.primaryweapons.com/store/pc/viewPrd.asp?idproduct=139&idcategory=

[Outlander Systems]

Pretty cool.

Have you seen the new PWS tube?

http://www.primaryweapons.com/store/pc/viewPrd.asp?idproduct=139&idcategory=

This is extremely interesting to me.

Am I reading correctly that it comes with its own buffer?

[unoactu]

Pretty cool.

Have you seen the new PWS tube?

http://www.primaryweapons.com/store/pc/viewPrd.asp?idproduct=139&idcategory=

This is the first time I've ever seen anything like this.
Looks like I was headed in the right direction.;)

[Tokarev]

http://www.primaryweapons.com/store/pc/catalog/PWS_EBT_L_1.jpg

Same idea but more money:)

I like the idea of a supported buffer tube and it seems that it would be some of the answer to carrier tilt and possible premature locking lug wear.

I talked to PWS a week or two ago about their tube and they told me they should be ready to ship right after SHOT.

[Razorhunter]

This PWS tube is most interesting.
Does anyone know how it attaches? I mean, other than screwing into the receiver, is there any other form of locking/attaching to the lower receiver? I can't really tell, but I'm sure there is something else that holding/locking it in place to prevent unscrewing.

Anyhow, since I am not currently looking to repair a piston gun, I do wonder how well this tube would function in a regular DI gun, or if it is even recommended to do so? I am most interested in the following comment PWS makes:

"A dead blow buffer is securely installed in the rear of the buffer tube to reduce carrier speed by an average of 10%, and dramatically reduce felt recoil."


I will be interested to see just how much FELT recoil reduction is really accomplished. Of course, I'm just wondering if this PWS tube will be ok for DI use in the first place? Any reason it wouldn't be?

[Jeffy]

This PWS tube is most interesting.
Does anyone know how it attaches? I mean, other than screwing into the receiver, is there any other form of locking/attaching to the lower receiver? I can't really tell, but I'm sure there is something else that holding/locking it in place to prevent unscrewing.Looks like it traps the buffer retainer.

[mildot]

I talked to the folks at LMT about the piston conversion for the MRP platform, very cost saving and for current owners the way to go IMO.
However the question about carrier tilt is a good one, so I'm curious is the upper receiver affected by this? for me this is important since the MRP is one continuous platform.

Are there any real concerns for a "recreational" shooter using the piston?

Overall I was pleased with my answers from the LMT folks but I still want to "guard" my investment.

The PWS tube is interesting but I don't think it would work with a Magpul UBR?

Cheers

[dtibbals]

I have an LMT Piston but don't have enough rounds out of it yet to really see any issues. I am not worried about it since LMT has a life time warranty.

[kentak]

I'm wondering if the following might be true:

1) Carrier tilt is basically a cosmetic issue on a part of the gun hidden from view.

2) The scuffing will be self-limiting.

3) CTS (carrier tilt scuffing, my term) will never cause a failure or malf.

[Thomas M-4]

I'm wondering if the following might be true:

1) Carrier tilt is basically a cosmetic issue on a part of the gun hidden from view.

2) The scuffing will be self-limiting.

3) CTS (carrier tilt scuffing, my term) will never cause a failure or malf.

1# You do not want the carrier tilting when the bolt is trying to unlock from the barrel extension it is going to put stress on the cam pin and the cam pin bolt hole.And probably the lugs also.
2# It may limit but you are introducing a force the system was never designed to handle.
3# refer to 1#