M15 feed ramp issue... *pic*

[brentn]

Hopefully I can get some advice here on what to do.

Just got my M15 yesterday, quite happy with it until I went to load up some rounds. I was using live hollow points in my house, not actually shooting them but just seeing how they fed. More curiousity more than anything, I wanted to see how the rifle worked feeding rounds, see how they eject, etc.

Loaded up 5 rounds and 1/5 seemed to have a stoppage, and every time it was when a round was pointing nose up into the breech, or it was caught on the feed ramp... Very similar to my 1911 when using win clean rounds
Not so hot I thought for a brand new rifle.

So I field stripped the rifle and noticed that the feed ramps from the barrel do not line up with the feed ramps on the upper reciever... Not all the way anyways. The right side in picture is aligned perfectly, where as the left there is a small small little edge protruding from the side. The picture explains all.

To me, this looks like a problem. I did some reading and found out that the feed ramps on an M4 barrel are different than that of a regular 20" barrel. I was also told that the upper reciever also had different ramps for M4 jobbies versus regular full length barrelled uppers...

Could it be that my barrel was put into an upper reciever meant for a 20" rifle?

I really really don't want to send this back.. The company offered to build this rifle for me because armalites were 4 months wait time and they had all armalite parts except for the reciever. They also told me that they only had
a2 uppers and not a4's, which I didn't mind seeing as I wanted an A2 anyways.


I figure the following:

-Get it sent to a gunsmith and pay for a feed job
-Order an A4 upper that (hopefully) has the right feed ramps and save this A2 upper for a 20" that I do plan to assemble.
-Send it back and wait 4 fricken months for an a4 upper.
-Send it back and maybe they have an a2 upper for a carbine barrel?

I'm from canada so before you guys start telling me to go here or there for an a4 upper keep in mind that I cannot get stuff from the states shipped here.

for reference heres a pic of the rifle

Your advice is extremley appreciated.

 

[Bartholomew Roberts]

Where is it catching on the feed ramp? Are you letting the bolt slam home or are you riding the charging handle? Finally, have you tried it with a different magazine? In my experience, a good magazine is more important to resolving most feed issues than the feed ramps are.

 

[brentn]

The magazines are pinned to 5 rounds, they cannot be inserted into the magwell with the bolt home when loaded, they will only lock into place if the bolt is hanging back.

Should I try just two rounds and see if they feed?
Does that picture look like a problem to you?

I'll assemble the rifle right now (just detailing it of all crud and oiling it all myself) and take a shot of a misfeed and you be the judge.

Thanks bart.

 

[Bartholomew Roberts]

Mags like the ones you describe are notorious for feeding issues. I would try some mags that you know feed correctly - either yours if you have them or someone else's if not.

I understand the bolt has to be back; but when you let the bolt forward are you just slapping the release and letting it slide home or are you pulling the charging handle and trying to ease it home? ARs don't like the easy route, you just need to let it slam.

Does that picture look like a problem to you?

It is a little worse than I usually see; but it isn't unusual to see the barrel extension ramps and the upper receiver ramps slightly misaligned. Unless the tip of the round is obviously catching the ramp at the sharp edge where it is misaligned, I don't think they are the problem. Where is the tip of the bullet sticking on the ramp?

 

[Kurt_D]

The feed ramps look fine. Yes that is a M4 barrel ext. The receiver looks to have M4 ramps too.

I'd vote for a mag problem too. First find some mags you know works (beg or borrow if you must). You say it was a build, also check to insure the mag catch is tightened enough. If it's loose the mag can sit too low and hang on the ramp. 1 extra turn should be enough.

 

[brentn]

btw, I am using hollowpoints that I bought ages ago for a different purpose.
They are the only rounds that I have to test, but so far it seems that the flat tip is catching on that lip you see on the left side.

Most of the time, pulling the bolt all the way back and letting it slam home, it feeds just dandy. But theres that one time in a while that the tip of the hollowpoint catches on the ramp, left side in the picture, the obvious lip.

Theres not enough controlled variables here to really see the true problem. I'm going to have to buy a box of FMJ's and goto the range and just see if its as bad as I think it is. With spitzers I really don't think there will be a problem with feeding, but then again maybe..

I will try and get some 10 round AR-Pistol magazines, I know those work rather well, at least thats what I have been told.

bart, two questions

-Are there M4 barrel uppers? Is what I said correct about M4 barrels and uppers? Or is this just F*d up tolerences from the manufacturer that cause these sorts of things?
-Is it worth having it ported and smoothed out by a gunsmith if its a problem with spitzers at the range?

kurt, how do I twist the mag button?


Thanks buddy.

 

[rino451]

I bet it'll be fine if you just shoot it. You'd be surprised at how much the feed ramps chew the crap out of the bullets on the way in. As was said before, either rack and release or use the bolt release.

 

[brentn]

Good to know, one of the rounds got caught in the ramp and while trying to release the bolt on it so that it would chamber, the bullet tip collapsed into the casing! heh..

Testing this out further, its defenitly one of the mags, doesn't happen with the other magazine. I can only conclude at the moment, that its the 'pinch' marks on each of the narrow sides of the magazine, to not allow the follower to go past the 5 round point. The pinches are messing up the spring I think, and could have also caused some warpage on the upper part of the magazine, allowing the follower not as much freedoom to move.

Hopefully the 10 round mags can be filled to capacity and I don't have to worry about dropping 8 instead of 10 in there

I've spent all my fricken money on this gun, i barely have enough for ammo. So I can either buy a couple (200 round) boxes of ammo, or I can buy some 10 round magazines...

FYI, I got this from wolverine supply.com, they were nice enough to give me a custom flash hider, an extra magazine and a nice plastic rifle case for free. They took exactly 10 business days from payment to
-Assemble the rifle
-Get it certified with the canadian government
-Register it to my name (takes 4 days right there)
-Ship it to my house.
I thought that was pretty good service and a quick shipping time.

 

[hags]

Whatever you find the problem may be, those feedramps on the receiver don't look like they line up or index with the feedramps on the barrel extention.
Also, testing a firearm in this manner with live ammo in your home is at the very least unsafe and a poor indicator of actual functianality.
If someone did build you this upper from mix and match parts then that would explain the receiver/extention feedramp misalignment.

 

[brentn]

Yea I really need some snap caps. for what its worth I always had the safety on, finger off the trigger and the gun pointed at cement wall. Your right though, not the best idea.

I'll go and shoot it and see what happens

Thanks all for the advice.

 

[Bartholomew Roberts]

-Are there M4 barrel uppers? Is what I said correct about M4 barrels and uppers?

Those do appear to be M4 feed ramps and M4 ramps on the barrel extension. There is also no problem running an M4 ramped barrel extension on a normal ramped receiver. In fact, my main rifle is set up like that. You will run into feed issues if you run a normal barrel extension on an M4 ramped receiver though.

-Is it worth having it ported and smoothed out by a gunsmith if its a problem with spitzers at the range?

Depends on where it is hanging up. A quick look at the ramps when it hangs should tell you whether this will be helpful or not. If it has caught a small burr in the middle of the feed ramp, then a little jeweler's rouge may help. If it is catching the side of the ramp, then probably not.

Good to know, one of the rounds got caught in the ramp and while trying to release the bolt on it so that it would chamber, the bullet tip collapsed into the casing!

Setback during feeding isn't unheard of if the bullet does not have a cannelure on it (and many hollowpoints do not), even with perfect feed ramps.

 

[MechAg94]

If you must chamber a live round, get a big 5 gallon bucket of sand to point the barrel at.

 

[jpwilly]

Hollowpoints can at times cause feeding issues in an M4 especailly with a bad mag and even at times without. Try some FMJ and see if you still have issues. Also you need to let the bolt slam home when loading.

 

[brentn]

Update.

Went to the range today and picked up 140 rounds of 55grain FMJBT, they all fed perfectly. I had a couple FTF with the pinched 30 round magazines, but that was it, nothing hung up on the ramp.

Although the ramps look messed, they function fine, so I'm no longer concerned.

Love the rifle though, was alot of fun.

Thanks all for the help