M14 Forum banner

1 - 4 of 4 Posts

·
Banned
Joined
·
20 Posts
Discussion Starter #1
I have an Armscorp receiver (M14NM marked) with an SEI Medium Length 1:10 chrome moly barrel 18" (NM marked), NOS TRW Gas Block and piston (unitized), TRW Op Rod and Bolt (also NOS), Sadlak Op Rod Guide, unknown spring, all mounted on a CM Manufacturing stock. I put it in the stock but I did not do any of the assembling or headspacing, although my gunsmith checked the headspace when I got it in.

Today was my first time firing it, got it off a board member here and have had it a while, just hadn't gotten around to shooting it, didn't think it would be a problem since my gunsmith gave it the thumbs up. It came in bone dry, so I put a VERY light coat of lithium grease on the bolt roller and receiver slides, put a VERY small amount of gun oil on the spring and guide (what I used to do on my Polytech), and took it to the range. I noticed when re-assembling the op rod that it took a LOT of compression force to get the guide into the channel... considerably more than my Polytech I used to have and when chambering a round it requires considerably more force.

At the range I started putting some rounds down-range and although she kicks like a mule, she has a REALLY smooth trigger (also TRW), no grittiness with a smooth break point, one of the nicest rifles I've ever fired, I was very pleased and at 50 yards I was putting them all in the bullseye iron sights from the get-go, happy camper, then suddenly, pulled the trigger and nothing happened. Look at the ejection port and stovepipe? really?

Hmmm,,, K. Pull the bolt back and see that there IS another round in the chamber, but the action did not cycle back far enough to eject the previous round OR **** the hammer, as when the stovepipe round fell out, I went ahead and released the bolt back forward and tried to fire it and nothing.

I cycled that round out and let it feed another round, fired and cycled fine. 3 or 4 rounds later, same exact thing. Then again 4 or 5 rounds later. Then again. OK, 3 strikes (plus 1), I'm out, something's wrong. Put her away and came home and tore her down.

Again, somewhat difficult to get the op rod free because the spring is so damn tight. Once I do, tilt test perfect. When tilting back up the gas piston slowly comes down (I can hear the slight vacuum air release as it does), it doesn't just rattle around. Not sure if that's good or not.

So any ideas here? Normal break-in? Maybe out-of-spec / bad / Chicom spring? I was going to replace it with a Sadlak spring to match the op rod guide, but before I started buying a bunch of parts, I wanted to get the thoughts of some people who know more than I do (which is probably most of you).

Thanks in advance for the help!
 

·
Super Moderator
Joined
·
11,039 Posts
The stiffer spring is from using the round guide, completely normal as its held straight and can't flex L/R like a flat spring guide will.

#1. When was the last time the inside of the gas piston/plug was cleaned out with drill bits?
#2. What ammo were you using?
#3. What brand of magazine's did you use? if not Check Mate or USGI?
#4. Gas cylinder and front band Unitized? while you had sporadic operation is the gas port and the gas cylinder aligned?
 

·
Banned
Joined
·
20 Posts
Discussion Starter #4
Hi Phil, thanks for the response, that makes sense.

To answer your questions:

1. The piston has never had a drill bit through it to my knowledge.
2. I was using Lake City 308, I only own that and South African 7.62 Nato
3. I was using a USGI mag and then a CMI mag. The Polytech mag I have sits too high and the rounds bind when cycling, I should probably put it on the board for sale to someone with a Poly.
4. Yes, the gas port is aligned, checked it when I got home with a very small punch.

I trimmed about an inch and a half off the op rod spring and it seems to be much closer to the proper tension I've had in other M1A's. Interestingly enough, when going through my parts bin to inventory FAL parts (building another one currently), I found another Sadlak op rod guide and two springs, one of which I think is Sadlak, but the other unknown one has also been trimmed by someone previous to me, almost exactly the length of what I trimmed mine too. Weird coincidence.

I'll get out to the range hopefully in a week or so.

SSight, I actually did have my scope mount screw protruding into the casing rubbing on the bolt when I first put it on, wouldn't cycle nicely by hand (bound up on the tilt test also), finally figured out what it was and sanded it down until it sits flush with the inside of the receiver now. Nothing seems to be binding in the receiver area, not that I can tell anyway, tilt test moves nice and freely.
 
1 - 4 of 4 Posts
Top