Custom Work on My Robarm XCR is almost done

[variablebinary]

The XCR as it comes from the factory is a good gun. However, nothing stays stock in my collection, so I integrated some of my own ideas and needs into the XCR's core design. Most of the changes are not sanctioned or offered by Robinson Armament. Proceed at your own peril if you choose to replicate anything I've done

All that said, here is my SBR'ed XCR.

- 10.5" CL 1/9 HBAR with opened gas port, 6.8 gas dial to add more gas into the action, turned down under the rail to .670 to reduce weight. This is the shortest barrel length possible on the standard XCR upper.
- 14.5" CL 1/8 HBAR, turned down to .610 under the handguard to reduce weight
- Gas blocks pinned on both barrels
- Welded Ejector bolts
- 12" length of pull folding tube stock
- Ambidextrous paddle style safety selector
- Gen2 single piece bolt catch
- Gen2 enhanced trigger system
- Troy Industries "stubby" half height XCR/HK416 sights.
- Magpul MIAD grip with winter trigger guard
- Troy Industries Rail covers
- Slightly pinched gas tube to eliminate all play
- VLTOR QD sling stud

Pics are not in chronological order.




















There is one additional modification I am unable to disclose at this time because it is experimental factory mod that Robarm doesn't want public at this time.

The last thing I need is the new stock. As a bonus, I'd take a nitride treated 1/7 barrel too for rounding out my XCR. I might add a 9" PDW 6.8 upper when they get done.

[Greg Bell]

That is one sexy XCR. I need to get one of those.

[IrishDevil]

I've been seriously considering picking up another XCR. Just waiting for 1/7 barrels to be a standard option and to see the new stock.

Your modifications seem to be well thought out and solid. I'm making some notes for my future purchase.

[Rated21R]

yep the 1/7 CHF barrels and the new stock would pretty much have me sold (of course I would need all the VB mods too).

[Redacted]

VB,

The rifle looks great and I really like the improvements!

I was wondering why the 6.8 gas block...did the 5.56 block not have enough adjustments for the 10.5" bbl??

Cannot wait to see your pics with the new stock!

[variablebinary]

Originally Posted by Redacted

VB,

The rifle looks great and I really like the improvements!

I was wondering why the 6.8 gas block...did the 5.56 block not have enough adjustments for the 10.5" bbl??

Cannot wait to see your pics with the new stock!

Let me clarify. It was not a complete 6.8 gas block, it was a 6.8 adjustable gas valve, which has a slightly wider holes, allowing a touch more gas into the action

All XCR gas blocks are the same actually.

[variablebinary]

Here is a slightly cleaner pic with an SBR AR15 to provide some context.

[Saginaw79]

I am ARd out so i may have to finally consider an XCR to make use of the crazy amount of Ar stuff I have accrued over the years

[notorious_ar15]

Are the Welded Ejector bolts really necessary on these rifles? Would safety wire be possible instead?

[MadDog]

Yes safety wire is definitely a possibility and the way I would go if I felt them necessary. Washer tabs are also an alternative. I have had my XCR for almost 5 yeaars now and mine have never loostened and have never had any loctite added either. They have stayed so tight that I don't even check them any more.

Whatever works for you,
MadDog

Sorry VB but I couldn't resist showing off another SBR'd XCR.

[variablebinary]

I made two more changes.

I replaced the foam on the stock with plastic, which I regard as more comfortable and sanitary

I also had the take down tab modified. It is now flat with ridges on the face, making it a snag free design. Now it takes a bit more effort to get the gun open, which I think is a good thing


Here is the last pic I took before the recent mods. I will add an update pic later.



Recent mods

[Marcus L.]

I really like what you've done, but why keep the A2 flashhiders? I've got a lot of catching up to do. I didn't know that RA had put out a Gen2 single piece bolt catch.

Where did you get the 1:8 twist barrel from?

Also, do you have a part number for those Troy BUIS? There is no listing for XCR/416 sights.

[variablebinary]

Originally Posted by Marcus L.

I really like what you've done, but why keep the A2 flashhiders? I've got a lot of catching up to do. I didn't know that RA had put out a Gen2 single piece bolt catch.

Where did you get the 1:8 twist barrel from?

Also, do you have a part number for those Troy BUIS? There is no listing for XCR/416 sights.

I actually prefer the A2 over muzzle devices. I've tried a few, and have always gone back to the A2. I probably wont change unless I get some suppressor that mandates it.

I traded a 1/9 for a 1/8. The guy I traded with wanted to shoot some ultra light varmint grenades.

Troy part numbers are:

Front sight - P/N 1614001-19
Rear Sight - P/N 1614001-18

[Marcus L.]

VB,

Is the pinned gas block bolt a custom job, or is RA doing that to new rifles?

I'm thinking of using red loctite on mine for the 2k endurance run just to make sure that it doesn't get loose.

[variablebinary]

Originally Posted by Marcus L.

VB,

Is the pinned gas block bolt a custom job, or is RA doing that to new rifles?

I'm thinking of using red loctite on mine for the 2k endurance run just to make sure that it doesn't get loose.

I had it done at a machine shop. And red loctite wont hold. The gas block will heat and destroy the seal.

Dont quote me, but loctite breaks down at 400 degrees I think

[HOPLOETHOS]

Nicely executed blaster.

[eternal24k]

Looks slick!
I was holding off on an XCR for the ACR, but with the recent estimated price and other details, I am thinking XCR

[olds442tyguy]

I'd be interested to see the new stock.

[RogerinTPA]

Your blaster looks sick! Well done!

[Cagemonkey]

Originally Posted by variablebinary

I had it done at a machine shop. And red loctite wont hold. The gas block will heat and destroy the seal.

Dont quote me, but loctite breaks down at 400 degrees I think

You think rocksett would work on the gas block set screw. Also, whats the torque specs for the set screw.