Bushmaster XM15 break in?

greywolf67nt

greywolf67nt

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I got a brand new Bushmaster XM15 and a bunch of brand new LAR mags.
Went out to the range today and had to use the forward assist or rack it on the first couple of rounds in each mag.
Is this normal? Putting round number 9 and 10 into the mag was a beeyatch!
Am I sort of correct in thinking this will get better?
 
Ya could be a mag thing, I'd try it with 8 and see how she goes. Could also just need a break in period.
Did it work with 5 rounders?
 
My bushmaster has no issues with usgi or lar15 mags. i am noticing atrs at15 mags do not drop free with empty mag in lock back.
 
Not sure if this is your first AR or not so I'll assume you're less experienced with the platform.
If you haven't already done it strip it and clean all the factory grease out of it and then lube all contact points between the upper and the bolt carrier and also lube the bolt before putting it in the carrier. AR's like oil not grease and I've helped more than a couple guys at the range get their AR running with only a bottle of oil.
A tight mag is not a rifle problem but they should loosen up with some use. Just be sure to insert the mag on an open bolt and use the bolt release instead of releasing it with the charging handle and riding it in, just let it slam closed as it does when it's cycling.
 
cr5 said:
Not sure if this is your first AR or not so I'll assume you're less experienced with the platform.
If you haven't already done it strip it and clean all the factory grease out of it and then lube all contact points between the upper and the bolt carrier and also lube the bolt before putting it in the carrier. AR's like oil not grease and I've helped more than a couple guys at the range get their AR running with only a bottle of oil.
A tight mag is not a rifle problem but they should loosen up with some use. Just be sure to insert the mag on an open bolt and use the bolt release instead of releasing it with the charging handle and riding it in, just let it slam closed as it does when it's cycling.
Click to expand...

Yes I am an AR virgin.
I did tear it down and cleaned it and oiled where the instructions told me to and I was fairly liberal.
Maybe I will do it again just in case I missed a spot.
 
greywolf67nt said:
... had to use the forward assist or rack it on the first couple of rounds in each mag.

...Putting round number 9 and 10 into the mag was a beeyatch!
Click to expand...

Hmmm. Sounds to me like bad mags. Let's build this scenario, step by step.

You are starting with an empty rifle. Is the bolt open or closed?

You insert a magazine. Does it seat easily or with difficulty?

You charge the rifle: how do you do that, with the charging handle or with the bolt hold open?

There is a malfunction. What stopped? Where did it stop?

You clear the malfunction. You said you used the forward assist. Was that a simple tap, or did it take effort?

You want us to take the time to diagnose your problem, you need to take some time describe the problem.
 
BattleRife said:
Hmmm. Sounds to me like bad mags. Let's build this scenario, step by step.

You are starting with an empty rifle. Is the bolt open or closed?
Click to expand...

Empty rifle bolt open.

You insert a magazine. Does it seat easily or with difficulty?
Click to expand...

Slips right in.

You charge the rifle: how do you do that, with the charging handle or with the bolt hold open?
Click to expand...

First couple with bolt catch last 4 with charging handle.

There is a malfunction. What stopped? Where did it stop?
Click to expand...

Partially stripped top round and came to a stop.

You clear the malfunction. You said you used the forward assist. Was that a simple tap, or did it take effort?
Click to expand...

About 3 fairly good presses on the assist and bolt would then close and lock up.

After the first 2 rounds like this it functioned perfectly.
They are brand new mags so I am wondering if I should not fully load them for the first few outings OR fill them then repeatedly remove and replace the top 2 rounds?
 
OP,
Did you try just loading 3 or 4 rounds in a mag?
Did you use the ping pong paddle or walk it close?

But no, you don't need to break in an AR like this.
 
Sinasta said:
Too much friction for the rounds to strip out of the mag. I'm assuming they're metal mags?
Click to expand...

This is my first guess as well, though if true the bolt should move forward and the round chamber easily once the forward assist has forced the round out of the magazine. I also would have thought that once the first round is gone subsequent cartridges should work fine.

If it is the mags, trimming the mag spring or the bottom of the follower could ease some of the friction.
 
BattleRife said:
This is my first guess as well, though if true the bolt should move forward and the round chamber easily once the forward assist has forced the round out of the magazine. I also would have thought that once the first round is gone subsequent cartridges should work fine.

If it is the mags, trimming the mag spring or the bottom of the follower could ease some of the friction.
Click to expand...

The first round needs 2 or 3 presses of the forward assist. The second round maybe one press then the next 8 work perfectly.
I am going to have a good look at them today and see if there are any rough edges or such and then try running them a few more times before I start trimming springs and followers.
 
It's your magazines. If it takes a hell of a lot of force to push in those last two rounds when you're loading them and then those first two rounds are really hard to strip off the top of the magazine, 1+1=2 buddy.
 
So tonight I took the mags apart and the feed lips were SHARP. Rounds 9 and 10 came out with pretty good scratches on them.
took my stone to them and rounded off the corners and now they go in and out with very little force necessary.
Time to go to the range tomorrow and see how it goes.
 
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