so I finished my new AR22 build. Everything went well - it is as follows:

- TACCOM barrel

- CMMG "India" .22 bolt

- CMMG .22 upper (has improved charging handle and dust cover for .22 applications.

- PRI free flow carbon barrel

- Noveske "chainsaw" (cosmetic second) lower with CMMG trigger

- Ace stock with TACCOM pressure plug

- Black Dog and CMMG magazines

I am experiencing a lot of jams/double feeds and FTF's. When I extract the rounds, I notice the bullet is usually gouged and dislocated (bent) in the case. So I took and it appears that the distance and angle between the ramp on the magazine
and barrel adapter is off. The gap is about 1/8" and the angle is off by about 30 degrees. The barrel is fully inserted into the upper with the nut properly installed.

So I tried a different lower - exactly same type of failures...

Now I have two AR-22's that don't run
(my TacSo Bushmasterl is on its way back to Boise per discussion with Colt)

Any immediate thoughts?

thanks

The gouged/bent bullet is usually an indication of sharp/abrupt entry into the chamber. Suggest checking the interface between the barrel collar and barrel chamber end. Try loading it slowly and watch how the cartridge enters the chamber. It might take some polishing at the barrel chamber to get this transition smooth out. An analogy would be M4 cut lower receiver and standard rifle barrel extension. I had to slightly cut the barrel chamber with a stone to get rid of the high ridge between the barrel collar and chamber.

I've found that with some of the higher end barrels, you have to spend a little more time dressing the edge of the chamber. The angle of attack on all AR15 conversions is tight enough that any sharpness on the chamber with catch the soft lead of the bullet and screw things up.

Remove the barrel from the weapon.

Slip the collar and feed ramp on there, in the correct position. Stuff a patch into the breech end

Use a dremel with the bluish/green rubber+fine polish polishing bits –– you want the "pointed tree" shape.

Do this:



But make sure you do it with the collar/ramp in place and that you try to keep the transition between the two nice and smooth. You must also gently radius away the sharp edge at the TOP of the chamber as that's a hang-point too.

DO NOT REMOVE TOO MUCH MATERIAL –– the 22LR shell is thin and you must not remove too much material or you'll have an unsupported chamber with blow outs. I'd actually remove slightly less material than in the above photo.

Now, that's only half of the equation.

You need to dress the bolt face (again with the soft rubber and fine polish bit) Not only the chamber face but any sharp edges. You want the rear of the 22LR round to be able to "jump" up into the rim cut-out in the bolt face as soon as the rim clears the mag feed lips.

A very good point. But this sort of tweak is common, at least among my friends and shooting colleagues.

Something is not adding up to me. I guess I'm confused.

Take a look at this picture.....does the collar look like the center picture? Your collar should be showing a flat at the end of the ramp....and be nickle plated too.


The overall length of the colllar is .725" +/-.005......measured from the front face to the end of the feed ramp.

Tim

How did you make out? Did you ever check the ramp angle by measuring it?

here are some pictures











the ramp angle I referenced in my original post was that between magazine and barrel to bolt adapter (image 2)

everything fits perfect let - there are some machining marks I have tried to illustrate (on the barrel to bolt adapter and the barrel extension ( the part of the barrel that protrudes into the upper. There are no issues with the assembly or fitment of parts. Thoughts?

thanks

I do not run Remington rimfire ammunition - period...

I have tried CCI, Winchester and Federal of various flavors and use BD or CMMG mags (latest design)... Something isn't right but the root cause is not mags or ammo. The Tacsol is in Colts hands as of Thursday - the complete rifle so it will be interesting to see what he has to say

If you look at the photos provided by TACCOM, labeled "Breech End Without Collar," and "Breech End With Collar," here and on their
website, no alignment pin is shown on the barrel extension. This may be just a case of pre-production part photos, or a feature Tim feels is
unnecessary, however, in all of my years of association with the M16 and AR15 I have never seen this. In my very first Air Force Armourer class
the Colt representative told us one of the important functions of the pin was to eliminate the possibility of rotation, as well as other functions like alignment.

Yes it is true that this is rimfire and not as important as it is for CF, but I would prefer there to be no chance for my barrel to rotate. Also, in
the case of disassembly/reassembly I always want my barrel to have the same orientation each and every time. I see this type of barrel design
precludes the use of a front sight, so one might say the pin is superfluous. That being said, what effect the lack of a pin has remains to be seen in
the long run.

Despite tightening the barrel nut, if there is a poor slip fit between the extension and the Upr Rcvr mortise, a poorly tensioned barrel nut will
not eliminate the possiblity of a loose barrel or barrel rotation in the absence of the pin. This probably is not the cause, because it is a rimfire gun,
but I do find the lack of alignment pin a curiosity, and could explain why there are two marks.

Most likely, whatever caused the 1st impact, was repeated because the barrel was removed, then, because there is no pin, it was assembled in
a different position and the 2nd impact took place. I readily admit I have no idea what could cause those impacts if the collar was in place.

Ted

Am I the only one that thinks its weird the barrel ends are pointed like that? Seems like that's just asking for feeding problems. Why not make it flat or even coned inwards instead of pointed? Am I missing something?

I have a TACCOM barrel in one of my uppers. Actually I removed a Tac-Sol LT barrel and inserted the TACCOM, using, of course, a CMMG bolt.(the collar on the TACCOM is not made to work with the Tac-Sol bolt. With that out of the way, my barreled upper runs 100% day-in, day-out. So, I think the design is not the problem. So, we need to look beyond the old favorites and try something new, right? The odd thing also, having problems with two very different designs at the same time. Just seems so odd.

so because it works for you no one else should have problems?

thanks for your help sir