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I received the Better-Mag Adaptor that I ordered from Redi-Mag.com today. This is the aluminum adaptor that allows S&W M&P 15-22 magazines to lock a CMMG/Ciener/similar rimfire conversion bolt open manually or on the last round fired in conjunction with the standard AR bolt stop. The order was placed on the evening of January 12, taking 3 days to get to me - pretty fast shipping from Oregon.
The main body of the unit is aluminum and fits into the magazine well from the bottom. It is equipped with a plunger on the side to help hold it firmly in the well. At the top rear of the unit we find a separate steel part which slides in a machined recess in the main body and has a slot which engages the AR bolt stop.
Installing the unit is pretty easy; remove the steel slider, place and hold it over the AR bolt stop in the location shown in the instructions while inserting the main unit from the bottom of the magwell. The magazine release needs to be depressed as the unit is pressed past the magazine catch. Once the unit is at the top of the well, the upper and lower are assembled normally. When an empty S&W magazine is inserted in the well and the operating handle cycled, the S&W magazine follower presses the Better-Mag steel slider upward and the AR bolt stop follows along. The conversion bolt is held open and remains open when the magazine is released, just as in a 5.56 mm AR. Depressing the AR bolt stop pad will press the slider down and allow the bolt to close.
No pads or shims are included for the S&W magazines; since all of mine had been used with the Catch 22 bolt stop, I had the Catch 22 shims on the front spines of the magazines. I simply cut off enough of the top of the plastic shim with a hacksaw that it would not interfere with the Better-Mag main unit and left the rest on the magazine. That worked well and the magazines fit firmly into the well as well as dropping freely when released. I did not have an unmodified magazine to test.
At the range today it worked well with approximately 300 rounds being fired. I noted two minor issues: On a couple of occasions, the bolt stop pad would be hard to depress, requiring a healthy smack on the side of the rifle to close the bolt. I could not find any reason for this; I lubricated the Better-Mag slider in accordance with the instructions during installation and more lube did not seem to affect it either way. The other issue was not really a fault with the Better-Mag Adaptor, but with the S&W magazines. If one is not paying attention when loading them, the top round may not pop up into the feed lips, but remain slightly below them. If that happens, the bolt will push the round into the inside of the front lip of the magazine instead of feeding it smoothly. Once I realized the issue, it was not repeated.
Overall, I prefer this system to the Catch 22 replacement bolt stop. If needed, my dedicated rifle could be returned to 5.56 MM by simply removing the Better-Mag unit and installing a centerfire upper. That's not so easy for the lower that has the Catch 22 stop installed as the bolt stop roll pin would have to be driven out, the Catch 22 stop removed and a standard bolt stop installed. I actually have a polymer lower with the Catch 22 stop permanently installed now as there is no access to drive the stop pin out on this particular lower (an EP lower). Additionally, the Catch 22 stop that I have appears to have been made of a too-soft alloy, allowing the bolt stop roll pin to wallow out its hole in the stop, which causes the Catch 22 stop to fail to lock the bolt open on the last round with increasing frequency.
The main body of the unit is aluminum and fits into the magazine well from the bottom. It is equipped with a plunger on the side to help hold it firmly in the well. At the top rear of the unit we find a separate steel part which slides in a machined recess in the main body and has a slot which engages the AR bolt stop.
Installing the unit is pretty easy; remove the steel slider, place and hold it over the AR bolt stop in the location shown in the instructions while inserting the main unit from the bottom of the magwell. The magazine release needs to be depressed as the unit is pressed past the magazine catch. Once the unit is at the top of the well, the upper and lower are assembled normally. When an empty S&W magazine is inserted in the well and the operating handle cycled, the S&W magazine follower presses the Better-Mag steel slider upward and the AR bolt stop follows along. The conversion bolt is held open and remains open when the magazine is released, just as in a 5.56 mm AR. Depressing the AR bolt stop pad will press the slider down and allow the bolt to close.
No pads or shims are included for the S&W magazines; since all of mine had been used with the Catch 22 bolt stop, I had the Catch 22 shims on the front spines of the magazines. I simply cut off enough of the top of the plastic shim with a hacksaw that it would not interfere with the Better-Mag main unit and left the rest on the magazine. That worked well and the magazines fit firmly into the well as well as dropping freely when released. I did not have an unmodified magazine to test.
At the range today it worked well with approximately 300 rounds being fired. I noted two minor issues: On a couple of occasions, the bolt stop pad would be hard to depress, requiring a healthy smack on the side of the rifle to close the bolt. I could not find any reason for this; I lubricated the Better-Mag slider in accordance with the instructions during installation and more lube did not seem to affect it either way. The other issue was not really a fault with the Better-Mag Adaptor, but with the S&W magazines. If one is not paying attention when loading them, the top round may not pop up into the feed lips, but remain slightly below them. If that happens, the bolt will push the round into the inside of the front lip of the magazine instead of feeding it smoothly. Once I realized the issue, it was not repeated.
Overall, I prefer this system to the Catch 22 replacement bolt stop. If needed, my dedicated rifle could be returned to 5.56 MM by simply removing the Better-Mag unit and installing a centerfire upper. That's not so easy for the lower that has the Catch 22 stop installed as the bolt stop roll pin would have to be driven out, the Catch 22 stop removed and a standard bolt stop installed. I actually have a polymer lower with the Catch 22 stop permanently installed now as there is no access to drive the stop pin out on this particular lower (an EP lower). Additionally, the Catch 22 stop that I have appears to have been made of a too-soft alloy, allowing the bolt stop roll pin to wallow out its hole in the stop, which causes the Catch 22 stop to fail to lock the bolt open on the last round with increasing frequency.
