Skorp, I read your post quickly and did not note the 10.5-inch tube.

OK, sounds like you need the 11.5 barrel, but if you can get one the issue 14.5. Go with a rubber D-fender or O-ring for under the extractor. You have no way of knowing (or fixing) the size of your gas port. 10.5s are notorious for being picky feeders (the 11.5" Colt Commando is the shortest in-production barrel Colt produces and i have seen in general issue because of the fine balance between short and functional).

Any of the heavier buffers will keep you in good stead with the 11.5 or 14.5.

Good luck.

skorp, let us know how make out. I would imagine your odds of procuring an 11.5 in theater are fairly low, so I would concur with the 14.5 suggestion. And a complete Colt bolt group if you can find one as well, or FN for that matter.

LMT's product is inconsistent to say the least. What might be acceptable for the recreational shooter, who has time to wring out any bugs, is UNSAT for a guy like you. The shit has to WORK right out of the box.

Stay safe!

skorp,

while shorties are traditionally finicky and LMT has their share of problems I think we should keep the baby and the bathwater in the tub for the time being. A heavier (H3) buffer is necessary for your configuration as well as increased extractor tension. Can you lay hands on an H3 from the links I sent?

tweak - will have a look at the links this am my time for buffer weights, thanks for the steer.

The LMT extractor was single spring.

If I can find a 14.5" tube, it's going on for testing.

Reliability is king.

tweak - have managed to source an H2 buffer, and an armorer is going to either put an extra weight in it, or get an H3 buffer from somewhere

may also have a line on a 14.5" tube from a tried and tested mil-spec manufacturer. wait out on that one.

skorp

JLM

intel was of good value and will be disseminated accordingly here. thanks very much.

skorp

Thats pretty disappointing about the LMT barrel. All my LMT products have been great. FWIW, Wes Grant puts an O-ring in every 10.5 bolt he ships. Then he test fires 90 rounds really fast (he uses his RR M16 for that). It seems to be an almost mandatory modification.

Then he test fires 90 rounds really fast

Probably a good thing, allthou LMT alledgedly does that

Binned eh? I somehow suspected you were British

g'day

I shall not take offense at being mistaken for a brit, although as an aussie, it's a serious insult to be labelled as a 'whinging pom', or 'whinging pommie b*stard' (your preference - but say it with feeling). As fellow ex-colonials with your own proud history of hammering the brits for a spot of entertainment, I know you'll understand.

On to other things. I test fired the M4 today and only got time for 5 mags (who knows if that's enough), which went through without any issue bar one. The bolt will not hold open on the last round. I did a function test at the beginning and the bolt will not hold open on any of the mags I tried, new or old. I don't know if this is a drama with the bolt catch or a gas issue. I suspect the former as it will not hold open when I put an empty mag on and cycle the action(?) Correct me if I'm wrong. When I push the bolt hold/release catch in manually, it catches the bolt in the correct position.

skorp

Skorp, check your bolt catch. A sub-standard one won't have enough projection on the front end to catch on the back end of the mag follower (forcing the catch up to lock the bolt and carrier to the rear).

"Ozzies I like. Ruperts, well..."

Bolt catch assembly here:

http://www.ar15.com/content/guides/assembly/lower/#boltCatch

Hopefully you can get a Colt or FN catch.

Is it a LMT lower as well?

Ozzie eh? Well all right

Take care, and stay safe!

OK, let's get back on track,

Strip the bolt out of the carrier and slowly slide the carrier into the upper, feel for ANY resistance as the gas tube enters the carrier key. If there is any interference you can adjust the end of the gas tube with a large flatbladed screwdriver. Adjust the fit until the carrier closes without any interference.

Then take your newly rebarreled rifle and drop a round in the chamber, drop the bolt, press in on the bolt catch, and fire the round. Repeat this test several times to be sure.

If the bolt locks back properly you have a bolt catch/magazine problem. If it doesn't lock back you have a gas problem.

The bolt catch only needs enough spring tension on it to hold it down, no more. Compare the fit and tension of your catch to other ARs that you have at hand. Less tension is better on a bolt catch up to the point that the catch starts engaging in the middle of a magazine.

You should be able to deburr either the bolt catch slot or the catch itself and/or adjust the bolt catch spring.

Make sure that there is not a disconnector spring under the bolt catch, it's been known to happen.

You get this rifle fixed and we'll make you an honorary Seppo, then you can chat up Mr Lewis about his bodgy parts.



JLM,

It's a BFI lower, more "milspec" parts.

Tweak

No resistance as bolt carrier key meets gas tube.

Can't get the bloody bolt catch out as don't have anything to drive the pin out with. Will try to get it back to the armorer at some stage. Frustrating.

It won't hold open when I put an empty mag on and pull the working parts to the rear, either.

Will try the function test you described, when I can get on the range (who knows when that will be).

@#$%^!!!!

Honorary Septic, hmmm?