CMMG 22LR Conv. kit doesn't chamber

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[ARCHIVED THREAD] - CMMG 22LR Conv. kit doesn't chamber

Posted: 7/20/2018 8:46:07 PM EDT

Just got this today, used.

The CMMG bolt wouldn't chamber on 2 Palmetto uppers... looks like the "gold" part doesn't fit the lugs on my AR's...

They are 5.56 NATO chamber

Please help

new picture:

edit 2:
14.5mm

Posted: 7/20/2018 9:48:30 PM EDT

[#1]

Is that a 22lr with a 223 in it

Posted: 7/20/2018 9:56:54 PM EDT

[#2]

Quote History

Quoted:
Is that a 22lr with a 223 in it

View Quote

.556 upper with the conversion kit. I added a third pic.

Posted: 7/21/2018 8:23:33 AM EDT

[#3]

take a picture and post it of the camber adapter with the black shipping protector removed. So we can see it.

Posted: 7/21/2018 10:37:20 AM EDT

[#4]

Measure the outer diameter of the bronze collar. From what I've read and my limited experience, it should be about 14.3 mm. Much larger than that, and it may need to be turned down to fit into the lug region of the barrel extension on some barrels.

Also, make sure that you have the charging handle pushed all the way forward. A stiff charging handle latch will retard complete insertion of the .22 conversion assembly.

Best of luck with your conversion unit.

MHO, YMMV, etc.

Posted: 7/21/2018 10:43:03 AM EDT

[#5]

556 and 223 are slightly different is that made for 223 chamber

Posted: 7/21/2018 10:49:56 AM EDT

[#6]

Quote History

Quoted:
take a picture and post it of the camber adapter with the black shipping protector removed. So we can see it.

View Quote

~~Once he takes the condom off it will fit properly and we'll all laugh.~~

Well, bugger. Customer service, the lathe, or Dremel your way to a dedicated bbl.

Posted: 7/21/2018 10:54:48 AM EDT

[#7]

It is not unheard of getting a chamber insert that is out spec. Could be tolerance stacking but the brass is the same whether 5.56 or 223 Remington. Only the throat or leade is difference between 5.56, Wylde or 223 Remington chamber. PSA advised someone on another forum they sourced their conversion bolts from CMMG. I suspect you got an out of spec chamber insert or failed to remove the protective plastic sleave.

Posted: 7/21/2018 12:02:49 PM EDT

[#8]

I have updater the op with a new picture to show how far the conversion kit goes.

PS>
The black protector has been removed before I inserted the bolt group.

Edit:

Quoted:
Measure the outer diameter of the bronze collar. From what I've read and my limited experience, it should be about 14.3 mm. Much larger than that, and it may need to be turned down to fit into the lug region of the barrel extension on some barrels.

Also, make sure that you have the charging handle pushed all the way forward. A stiff charging handle latch will retard complete insertion of the .22 conversion assembly.

Best of luck with your conversion unit.

MHO, YMMV, etc.

View Quote

I'm measuring 14.5, many thanks

Posted: 7/21/2018 3:52:51 PM EDT

[#9]

I have had a problem the same way with a 5.56x45 chambered PSA upper. My CMMG bolt worked fine in 3 other uppers without a hitch. I cleaned up the bushing and reassembled the chamber adapter. I then made a flapper out of a wooden dowel and 3 grits of sand paper. I ran it at slow speed and went from 240 to 400 grit paper until the unit fit as it did in my other uppers and since life has been good.

[ARCHIVED THREAD] - CMMG 22LR Conv. kit doesn't chamber

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