1st Time Out: 11" XCR-L in 6.5G

[Sean K.]

In a separate thread here:

https://www.xcrforum.com/forum/15-fi...ype-2-mod.html

There's been some discussion from InVader (Post #8) with RA direct about my issue with ejection/bolt over base malfs. They said they thought it was the extractor, so I checked that and it appears in spec.

They also said don't go larger than .082" on the bbl port if I'm going to drill it up. Found it to be ~.078" in terms of it being a through hole, but the top face would take the tip of a .082" bit. Drilled it out to the .082" size...left the gas dial in factory size. For dial sizes, go here: https://www.xcrforum.com/forum/15-fi...ype-2-mod.html Post #26 for 6.5G in 11" bbl. ***EDIT***I also put the sizes below***

3rd time out was today. Brought known good mags and problem mags. Problem mags are still a problem. Good mags ran 100%. Ejection seemed stronger and more consistent with the larger bbl port....but that was at setting #7 and I tried #6 for a while, but the spent cases were only going maybe 8 feet or so on #6.

So, I think I'm going to contact ASC about warrantying the 4 bad mags and see if that cures all the bolt over base malfs. However, I'm still not convinced the gun is gassed correctly. Ejection moved forward to about 2 o'clock on both settings 6 & 7....and before it was more like 3 o'clock. On setting 7....it was throwing brass 15-20' which is fine, but seems not very strong for being at the highest setting. I didn't shoot it a lot on #6, but I'm not sure I'd trust it based on the much weaker ejection.

I'm planning mags first, then run it again and see.....

I may have to end up porting up a bit, I'd probably just do the dial first and not mess with the bbl port since .082" was the max size RA recommended. I'm thinking .093" for the #7 dial setting and #.082 for #6...which is what #7 is currently. Maybe drill 5 up to what 6 currently is.

Just for reference:

Stock from Rob Arms Type 3 Dial Port Sizes in 6.5G with 11" bbl:

7=.082"
6=.076
5=.070
4=.067
3=.064

[Sean K.]

4th time out this morning....

Ported bbl port up to .086"....also ported dial.

Position:

7=.086
6=.082
5=.076
4=.070
3=.067

Ejection on dial settings 7 and 6 were strong....5 seemed okay at first...went to 4 and had a bolt over base malf. Dialed up to 5....same problem. Not sure if it's problem mags or still a gas issue.

4 and 5 both seem undergassed still. Problem mags were #7 and #11. Both had bolt over base malfs and failed to lock back on empty.

Noticed that the problem mags I sent in for warranty and these 2 today have a similar oddity....after being fully loaded to 25 rounds and having a bolt over base malf....once I clear the malf and continue on with that mag until empty....the follower will make a popping sound if you press it down into the mag body about 1.5" or so. Mags that worked properly do not exhibit this popping/binding issue when pressing the follower down. Once the "pop" occurs...the follower even in problem mags cycles smoothly by pressing down that same 1.5" or deeper with your finger.

[fmunk]

Makes me wonder if RA would be better off with an adjustable gas system like the Kel-Tec RDB and RFB (which is FAL inspired I think?), instead of different sized ports. Would cut down complexity and chance for mix-ups.

[Sean K.]

Makes me wonder if RA would be better off with an adjustable gas system like the Kel-Tec RDB and RFB (which is FAL inspired I think?), instead of different sized ports. Would cut down complexity and chance for mix-ups.

FAL uses a ringed piston....like POF.

And their ejection isn't nearly as strong as the XCR's. The XCR is a lot more AK like in terms of the strength of ejection....or, overgassed (as some would argue). Personally, that's usually a sign of an ultra reliable firearm though....how far out it's kicking spent cases. Though, the argument that it's beating the shit out of the gun and giving more recoil than necessary could be valid; I just don't see it in the case of the components on the XCR or AK.

[Sean K.]

One more thing I need to try on this 6.5G....Unimags versus the ASC dedicated 6.5s. Might even need to try the Elanders...though I hear they have similar feeding issues from time to time. Really like this round though...it's very controllable in rapid fire. Can't wait to get the feeding issues figured out so I can test the accuracy.

[fmunk]

FAL uses a ringed piston....like POF.

And their ejection isn't nearly as strong as the XCR's. The XCR is a lot more AK like in terms of the strength of ejection....or, overgassed (as some would argue). Personally, that's usually a sign of an ultra reliable firearm though....how far out it's kicking spent cases. Though, the argument that it's beating the shit out of the gun and giving more recoil than necessary could be valid; I just don't see it in the case of the components on the XCR or AK.

Yah Kel-Tec's is a little different, here's a video. Over-gassing would have some effect on accuracy too, no?

[Sean K.]

Yah Kel-Tec's is a little different, here's a video. Over-gassing would have some effect on accuracy too, no?

*Some* effect? Sure....how much? Debatable.

As for the video...seems like the major difference versus the RA Type 3 gas system and this is the allegedly (b/c he didn't take it apart to let us see how that dial/cap works) self-venting cap.

I'm not convinced having that many adjustments is a good thing or that finding a 'setting' for a particular ammo is realistic as it doesn't take into account how dirty the vent cap is, variability in the ammo....looked like Wolf or Tula in the video, or overall how dirty or worn in the gun is.

Can't really make any determination without seeing how that dial/vent cap is designed as to whether or not it's better than the Type 3. I wonder how well the Kel-Tec system would work on something with a shorter dwell time with the bbl port much closer to the muzzle as well.

[fmunk]

Good point. Near infinite adjustability is one of those things that sound good on paper but not practical in real use. A bit like those adjustable AR gas blocks that were all the rage not long ago. Specifically tuned soft shooting goes out the door the instant change in ammo or carbon build up occurs (like you said).

[navalbeaver]

I've got an RDB that shoots suppressed pretty well. You've got lots of options, enough to the point where you can get it to cycle slow enough to feel the action cycling the next round. It's one of the "better" adjustables out there but if you're going to run it on the razor edge, it's not going to be as reliable. It shoots soft but it still gets dirty, clearing FTF/FTE is a F^()!ng nightmare and there's still some gas but it doesn't have a direct route to your face. I wouldn't say I trust it for any sort of duty use but it's tons of fun at the range.

[Bret]

Sean, I’m new here and looking to get information about the XCR in 6.5 Grendel. Have you been able to get your 6.5 Grendel XCR running reliably?

I do have experience running 6.5 Grendel in an AR15 and M16. They run 100% using Elander mags in semi and full auto. I’v had a few failures using the Unimags running 6.5 Grendel (which run 100% on full auto in 7.62x39). The 6.5 Grendel upper is setup with an Adams Arms piston system, so it may not represent how it would run with direct gas. I’d definitely try the Elanders if you’re still having issues.