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Movement in upper and lower

5K views 16 replies 12 participants last post by  Sean K. 
#1 ·
Hi Guys,

Ive noticed that as the round count go up things loosen up on my XCR. My gas tube rattles but is no big deal but Ive just found that the upper and lower reciever have alot more up and down play then I used to have. I put a piece of tape between the upper and lower and seems to be ok. Is this normal? When the rifle is charged and ready to shoot its all tight. Once the rifle is fired and bolt is closed its quite loose with lots of up and down movement. This is my first black rifle and am wondering if this is normal?

Cheers!!
 
#3 ·
The gas tube is "supposed" to move, it's not fixed. If you just can't stand it, some folks have very slightly squashed one end a little so that it doesn't do that.

When the bolt is open it's resting against the bolt catch which is part of the lower, so it will hold some tension there. Out 3, only one of mine is a little loose, but not that much. I know some folks have had a good bit more play.
 
#4 ·
To remove gas tube rattle, tap it with a rubber mallet a couple if times. It will deform slightly and get a more snug fit

Between the upper and lower, use a tiny strip of skate tape on the lower where it meets the upper. That till tighten up the fit

The Bolt Catch will rattle less when a mag is inserted.

I hate rattles, so I eliminated them all on my own XCR
 
#5 ·
One of the things that make the XCR so reliable is that it doesn't have tight tolerances. Much like the AK47. Unlike the AR.
 
#6 ·
I too noticed the play between upper and lower increasing with the round count ;ast year. I was concerned enough to send the rifle to RobArms, where it was ministered-to by Terra. Her verdict: nothing wrong, shim with tape as needed. I find the tape annoying and a potential point of failure, but I have not worked on a more robust solution. Or maybe I need to be less sensitive to a little wiggle.
 
#7 ·
Might try an appropriately sized o-ring over the front nub on the upper receiver like they do on ARs to tighten it up. The green high pressure/temp ones seem to hold up better than standard black ones.

HTH,
Sean
 
#10 ·
Sorry JS, I gave you bum info. You cannot use an o-ring on the XCR b/c the upper receiver on the XCR's front "nub" (the piece of aluminum with the hole in it that the front pin slides through) does not have 4 sides to it like an AR. So, there's no way to slip an oring over it. I wonder if you could make a small 3 sided shim of rubber that would go around the 3 sides of the XCR nub and make a compression fit between the upper and lower? That would accomplish the same thing and would need to be probably an 3/32-1/8" thick to do the trick.

Sorry for throwing out a non-workable idea.

Sean
 
#11 ·
I made a pin out out of drill rod to replace the pivot pin on my XCR that is a full .250 diameter and a washer out of shim stock for the upper/lower joint.
That got rid of play at the front and helped with the updown at the back. Mine has very little play now.

This might be a little out there, but you could prep the part of the recoil rod that locks the upper to the lower at the rear and spray multiple coats of GunCote on it, building it up a few thousandths. It'd take alot of coats though and you'd have to bake it to cure the GunCote. Best to remove the spring as the baking temp would likely hurt it.
Pete
 
#12 ·
Well, digging up a 7 year old thread but I just bought a NEW black XCR-M /308 with competition length keymod and kinda shocked at the play/wobble between the upper and lower. Expected more from a $3500+ rifle .. over $4000 after tax and shipping in Canuckistan. I'd have just sent it back to Wolverine but waited a looooong time for this thing and wasn't keen on spending another $100 on shipping it back and forth .. for nothing likely I figure. I don't think it came from RA like this as Wolverine just puts them together as needed. You guys ever figure out an acceptable method to tighten this up besides tape on a rifle of this cost? Love the rifle, it's NON-Restricted and all but this poor fitment sure puts$ a damper on it and I can see it getting worse as the rounds put through it pile up.
 
#13 ·
Newer XCRs (M or L)...aren't that loose....

Do you have any feeler gauges to give an idea of how big the gap between the upper and lower actually is?
 
#15 ·
Yeah being a brand new model I didn't expect the play people said was corrected years ago. I figure because I went with the 308 competition length keymod Wolverine likely just pulled a lower off a regular rifle. Got that impression when I ordered it but I don't know for sure .. hard to believe RA would ship that out. I will call them I guess .. had a scope, ADM mount, and a pile of other stuff coming so was anxious to get it set it up and shoot the damn thing after waiting so long, haha.

There is a LOT of side to side wobble in the front pin area yes, if I open it up just slightly (at take down latch) the lower moves back & forth laterally close to 1/4". Play seems to be mostly in upper lug/hole. When latched if I pull the upper back tight the slop/rattle goes away .. thought I might find a fix here with a new pin/bushing/shim/etc as I knew many older rifles had the issue. I can see a little day light when locked but the fit looks pretty good really, lock up at take down latch/spring is good, spring is good (very firm to depress) and the lug on the end of the spring fits well in the receiver pocket. It's the hole in the take down pin in the upper lug that seems excessively sloppy. I guess a custom worked bushing may do the trick. Never handled another XCR to compare it to ... just didn't expect to be able to shake the rifle holding on to the grip and hear it rattle like a $700 AR. Maybe I just expected too much .. appreciate the replies anyway. Rifle is a blast to shoot and zero issues gobbling up Hirtenberger surplus so far with gas set at 5 .. going to bump it down to 4 and see how it goes. Pretty hot round.
 
#17 ·
Open, even slightly, isn't the way to test for wobble.

Older L lowers, pre-M, were different than newer L uppers.....the spec was changed sometime around the 5K-7K S/N mark to tighten up any slop. I don't believe the -M ever suffered from the slop issue, so swapping a newest version comp upper onto an M lower shouldn't have resulted in the issue....unless RA has made another "tweak" to the spec that we're not aware of (entirely possible).

Sounds like you just happened to get one that's sloppy. RA will likely want you to actually quantify the slop while it's assembled if you're hoping for a fix.... again, feeler gauges are your friend here.
 
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