Robarms XCR FAQ post

I took the barrel off and clamped it in my mill. Then machined a flat through the spot weld with a carbide bit - ten minute job. A drill bit is hard to keep centered.

what size of bit?
I was thinking about grinding it flat, marking it, then drilling.

haha why do you have to be so far away? Something tells me just my drill isn't going to cut it... and not a chance I'm trusting it to a local shop.
 
Hello everyone,

Long time lurker, first time poster.

Does anyone know of any manufacturer or supplier of shorter barrels for the XCR? I'm fully tracking that Wolverine has the sole supplier status from Rob Arms in the States, and they will not bring in the shorter barrels for fear that the entire XCR class will be reclassed as Restricted. I think that point is getting close to proven moot with the co-habitation of Non-Res and Res ACRs, but it's their call. Also understand that cutting an existing barrel is a non-starter (prohib).

Does any one know of a company that has plans on making short XCR barrels, a-la the non-Res barrels supplied thru Questar? I find the XCR in 223 to darn front heavy. I really like my XCR (personally, it's on par with my ACR, less the weight imbalance).

Just see if someone out there knows something I don't,

Thanks,
 
Herron Arms in Ont.
Hello everyone,

Long time lurker, first time poster.

Does anyone know of any manufacturer or supplier of shorter barrels for the XCR? I'm fully tracking that Wolverine has the sole supplier status from Rob Arms in the States, and they will not bring in the shorter barrels for fear that the entire XCR class will be reclassed as Restricted. I think that point is getting close to proven moot with the co-habitation of Non-Res and Res ACRs, but it's their call. Also understand that cutting an existing barrel is a non-starter (prohib).

Does any one know of a company that has plans on making short XCR barrels, a-la the non-Res barrels supplied thru Questar? I find the XCR in 223 to darn front heavy. I really like my XCR (personally, it's on par with my ACR, less the weight imbalance).

Just see if someone out there knows something I don't,

Thanks,
 
An old friend did the work. 5 flutes both before and after the gas block, he also designed and made that brake himself. It is our very own Craftsman 441 here. He had the dirty thing parkerized by a fella in Edmonton. His name escapes me, I will edit when I remember. Looks even better in person.

Looks sweet assembled!

The parkerizing was done by another CGN member, Murdoc at Arma-Coat.
 
what size of bit?
I was thinking about grinding it flat, marking it, then drilling.

haha why do you have to be so far away? Something tells me just my drill isn't going to cut it... and not a chance I'm trusting it to a local shop.

I used a 3/8" carbide end mill to completely remove the spot weld by machining a flat on the FH. Once the weld was removed, a few quick raps with a rubber mallet was all it took to knock the pin out - i got lucky, YRMV!!! If you don't care about keeping the flash hider pretty, you should be able to do the the same with a grinder. Trying to drill it out may be tricky, bit might wander, pin might spin...
 
I used a 3/8" carbide end mill to completely remove the spot weld by machining a flat on the FH. Once the weld was removed, a few quick raps with a rubber mallet was all it took to knock the pin out - i got lucky, YRMV!!! If you don't care about keeping the flash hider pretty, you should be able to do the the same with a grinder. Trying to drill it out may be tricky, bit might wander, pin might spin...

the flash hider isn't pretty, but i got it off!
 
Barrel bolt / Loctite

Recently I started having problems with the barrel bolt coming out. I didnt notice at first but had FTF every so often. Eventually I realized that the barrel is sliding in and out a little bit :eek:

I did use Loctite 271 at the time and it did not prevent the bolt from coming out.

I then contacted Robarms and was advised they use Loctite 277 and to tighten to bolt to 200 in/lbs (INCH NOT FOOT!!!). For those with torque wrenches in ft/lbs. Its approx 17 ft/lbs ...

Loctite 271 and 277 is essentially the same. The service temperature is 450-500F (depending which data sheet you use...).


If my barrel bolt came out despite having loctite 271 on it, it means that the barrel gets so hot that the loctite breaks down and then the bolt comes out, loctite or not.

After some searching I found Loctite 2620 which goes up to 650F. The stuff is neither cheap, nor easy to get though.

I have since applied the 2620 and torqued the bolt to 200 in/lbs. It has so far held up over a few hundred rorunds. I am not sure what the main contributor is, the torque or the loctite. Of course the bolt will now be somewhat hard to remove on purpose, which should be considered before applying the 2620 ...


Anyways, I hope someone will find this info useful (my manual states neither the torque not the loctite to be used)
 
^^^

Personnaly, I never had ANY problems with the barrel bolt getting loose and never used loctite...

I torque the bolt with an allen key wrench with a big L shape, with the long part vertical to the bolt, until I cannot turn anymore by hand...

Then, I turn the allen key on the side, so the small part of the "L" shape is vertical now.

I give a 45 to 60 degrees right turn, which is around 175-200 in/lbs...
Or for visual people, from 12 o'clock TO 2 o'clock... ;)
 
I recently started pulling the barrel, and the butt stock off so I can toss it in my back pack while I ride so I no longer locktite either bolt, even so they haven't loosened at all.
While I'm only running Irons or an eotec, my poi hasn't shifted any noticeable amount at all. I thing the key to keeping the barrel bolt tight is making sure
to seat the bolt properly in the indent. This may not neccesarily be when the barrel is pushed completely to the hilt in the reciever. If you can get a feel for it, in my opinion it's a very
repeatable procedure



So far I'm 4200ish rounds with only 1 cleaning at about 200 rounds and just recently again at about 4000. I still haven't experienced any sort of feed, eject or fire issue, other than a few unseated mag "bob" issues till I got the habit of smacking them in.

All in all it's my favorite possession, it's beat and abused but I bought it to use it and that I do. 100% satisfied.
 
other than a few unseated mag "bob" issues till I got the habit of smacking them in.

Instead of smacking the mags in take them apart and remove a short length of spring do this until you do not need to smack the mag they just click in nicely with the bolt closed.

I have done this to all of my LAR 15 10 round 223 pistol mags and 5 round 6.8SPC mags.
 
Instead of smacking the mags in take them apart and remove a short length of spring do this until you do not need to smack the mag they just click in nicely with the bolt closed.

I have done this to all of my LAR 15 10 round 223 pistol mags and 5 round 6.8SPC mags.

^^^

Good hint!
I'll try this out...

How much lenght of spring do i have to take out on a LAR-15 mag?
 
Not much maybe a coil maybe a bit more just go slow stop as soon as the fully loaded mag clicks in on a closed bolt...
 
Not much maybe a coil maybe a bit more just go slow stop as soon as the fully loaded mag clicks in on a closed bolt...

I tested all my LAR-15 Magazine BEFORE doing the modification to the springs and they all clicked in when fully loaded on a close bolt... Just had to push a little bit to make them clip...

Tried to take out one coil of spring on one LAR-15 magazine... It eased it but not enough as I thought... I still have to push it in the magwel with a little bang from under... :p
 
I just bought a used XCR and I'm wondering if there is anyone in Canada that makes
or can get an M4 folding stock adapter like the on RA sells?
 
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