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Fire4Effect
10-14-16, 21:00
I picked up my new LMT LM8MRPSC from the dealer this past Tuesday and noticed marks on the buffer. I examined the buffer and bolt carrier in detail and it appears the two sets of hash marks on the face of the buffer are most likely due to a burr on the bolt carrier. This does not concern me and I will cut some narrow strips of 320 or 400 grit abrasive paper to remove any burs on the face of the blot carrier slot for the buffer retaining pin.

http://www.fototime.com/A0836F040BF003E/orig.jpg

http://www.fototime.com/F6AE5E255116338/orig.jpg

What does concern me is the buffer is resting on the buffer retaining pin when the upper and lower receivers are closed. It is my understanding there should be clearance between the face of the buffer and the buffer retaining pin when the upper and lower receivers are closed. I can see some very light dimpling at the edge of the buffer face from the buffer impacting the pin during the test firing at LMT.

Using a light and a magnifier I examined all my other AR’s and I could see the buffer face lift off the buffer retaining pin just before the upper and lower receivers closed. This is not the case with my LM8MRPSC.

I tried the following to narrow down the problem:


Installed the bolt/carrier assembly from another AR that had good buffer pin clearance in that rifle in the LM8MRPSC. The result was no improvement in clearance.
Measured the diameter of the buffer retaining pin in my LM8MRPSC and compared it to my other rifles. They were identical.
Visually compared the location of the hole in the LM8MRPSC lower receiver for the buffer retaining pin with the same hole in my other AR’s. This is when I saw a difference. The holes on my other rifles appear to be further forward by the amount of clearance seen between the buffer retaining pin and the buffer face just before the upper and lower receivers are closed. See photos comparing the lower receivers of the LMT and DD.



http://www.fototime.com/B3B217AD6437049/orig.jpg

http://www.fototime.com/C4053292BB4C53A/orig.jpg

It appears the hole for the buffer retaining pin is too far rearward. Is replacement of the lower the only fix for this?
P2000
10-14-16, 21:30
I would send it back or if that is strongly not desirable remove the buffer retaining pin and spring. They aren't needed for function.

There was a post recently with a special offset buffer retaining pin recently that might work, but doesn't seem to be a proven design / use at your own risk.
markm
10-14-16, 21:39
If the retaining pin and buffer face don't show anything more than minor marking, I'd let it ride for a while. I'd watch for any egging of the buffer retainer hole, but It doesn't look like your situation is that serious.
waveslayer
10-14-16, 21:56
Just remove the buffer retaining spring and spring , you will be fine. Just remember when you are breaking open your rifle, otherwise you will have Jack In the Box come out after you

My wife thinks I only have 3 guns
Rifleman_04
10-15-16, 08:30
Just remove the buffer retaining spring and spring , you will be fine. Just remember when you are breaking open your rifle, otherwise you will have Jack In the Box come out after you

My wife thinks I only have 3 guns


Don't do this.
waveslayer
10-15-16, 08:31
Don't do this.
And why is this?

My wife thinks I only have 3 guns
Rifleman_04
10-15-16, 10:00
And why is this?

My wife thinks I only have 3 guns

Because that is ridiculous.

The marks on the buffer aren't that bad. It most likely won't get any worse over the life of the carbine. If the wear really bothers you and or really deforms something don't just start removing parts that are there for a reason to "fix" it. Send it back to the manufacturer so it can be corrected.
waveslayer
10-15-16, 10:05
Because that is ridiculous.

The marks on the buffer aren't that bad. It most likely won't get any worse over the life of the carbine. If the wear really bothers you and or really deforms something don't just start removing parts that are there for a reason to "fix" it. Send it back to the manufacturer so it can be corrected.
All it does is retain the buffer from popping out when you break open the AR. Nothing else. In fact check yours when you close it. The back of the BCG will contact the buffer and push it back right before it fully closes. It retains the buffer and spring. That is all. It is not ridiculous!

Take yours out and try it. I run 3 different AR'S like that, no issues at all!

My wife thinks I only have 3 guns
JSantoro
10-15-16, 10:51
https://www.m4carbine.net/faq.php?faq=vb_faq#faq_new_faq_item


4) Contact The Manufacturer or Dealer First – Internet forums have a large global audience and unsubstantiated or ill-informed comments will affect the livelihoods of a lot of hard working people in the industry. If you have an issue with a manufacturer or dealer that you would like to resolve, we ask that your first contact them to resolve it.

If you're asking whether or not you need a replacement lower, then the above (besides being a REQUIREMENT to which you agreed to abide by at the time you registered) might be a good idea.

Once you've done that, and provided them with an opportunity for redress, we can open this up again to talk about whether they saw to the item and how....or how they didn't. This is a Schrodinger thing: you've no way to know until you give LMT a shot at seeing to your concerns.