Undersized McFarland one piece gas rings....

AR/M4 AR Technical Discussion
1

I recently ordered (4) sets of McFarland gas ring to replace an old set in one of my guns, and to have a few extras on-hand. After installing one of the new rings in my AR, I found that the bolt would not pass the usual gas ring test. The bolt would just drop right out of the carrier. Once installed in the upper, there was not even enough of a friction seal to keep the BCG from sliding out of the upper:confused:

I removed the first set and installed another… same result. Third set? Same result. I just got a new set of Colt standard 3-piece gas rings from Brownells and all is well.

The BGC I have is a Daniel Defense.

I have used McFarland 1-piece gas rings over the past few years with great results. I will contact McFarland to get these replaced, but just wanted to give everyone a heads-up.

2

What is the OD size.
There was a recent thread on this subject.
My mcfarland gas ring measures .503 ‘’ Got mine from G&R tactical.

3

I recently bought a set of McFarland rings from Brownell’s and had the same experience. Test fired the gun and it short stroked. Replaced them with the original rings and it functions as it should.

4

Interesting. They are usually a bit on the BIG side (not undersized).

Were the McFarland gas ring you bought new? Meaning a recent run? We have ones that were made about a year ago and seem to work well (have not any come back to us with any issues).

C4

5

Just measured a bunch of ours and they are all at the .503 diameter.

C4

6

I couldnt tell ya how recent of a production they are. I just ordered them last week from Brownells.

7

Brownells was the source of the rings on the other thread as well.
Recommend you measure the OD and if it falls under .503 ‘’ order some from Grant.

8

Ive seen multipule complaints about the ones from brownells.
Wonder if theres someone out there copying them?

9

The one I recently got from Brownell’s measures .499.

It’s not worth the shipping to send back a part that cheap.

10

Whew! Just measured mine and thankfully it measured .503. :slight_smile: Got it from Brownells a while back.

11

Interesting. Has anyone contacted Brownells? Their customer service has always been outstanding and I’m sure they would like to deal with the issue directly.

12

i ordered some 2 years ago from Brownells, 0 issues. so might be a recent batch

13

Just curious so I can measure mine…

Are y’all measuring them installed on the bolt or off the bolt? Obviously, it should not matter but just FMI.

Thanks,
Sparky

14

Off bolt still new in zip baggy.

15

Off the bolt.

16

Thanks, I’ll measure tomorrow.

Sparky

17

OK, I finally got the chance to measure the one I have and, out of the bag and off the bolt, the OD is 0.4995". I assume spec is ~0.503 and if not what is proper spec?

Thanks,

Sparky

18

I don’t know if .503’’ is the spec. But new rings that measure .503’’ Seem to be working [ proper ring tension]. There seems to some floating around that are measuring under .503’’ and guys are reporting too little ring tension with them.

19

I figured that would be the case! Any idea where I can find data on what the proper spec is (original 3 piece design)? I can’t seem to find it anywhere.

Thanks,

Sparky

20

Here’s a link to the last discussion about these rings:

https://www.m4carbine.net/showthread.php?t=48234