Questions about lower receiver spec

[manbearpig]

Was hoping that someone could help me with two questions I had:

1- What is the proper width for the cut-out/channel in the lower receiver where the bolt catch occupies?

2- If this cut-out in the lower receiver is too narrow, is removing some material from the bolt catch a definitive fix? Or does removing material from the bolt catch lead to other problems that I don't foresee?

Thanks.

[Leaveammoforme]

It looks like 0.167" +/-.010 is the number you seek. I measured a couple stripped lowers and they were on the lower end around 0.160". Measured a spare catch and it was 0.155".

Your catch, lower or maybe even both are out of spec. If you whittle the catch you will possibly remove hardening. If you modify the lower you will remove anodizing.

Best bet is to replace bad part. That said, I'm sure it will work just fine if you "fit" the parts.

Free download of Unknown Origin blue print;
http://www.biggerhammer.net/ar15/cad/

[manbearpig]

Thanks a lot for your help Leaveammoforme.

[Clint]

Actually the slot appears to be .155 +.005.

This matches well with a .160 actual measurement.

The .167 +/- .010 is very loose, but that's OK because it is the clearance for the bottom end of the paddle.

One catch measured .155, but several others measured around .148.

[lysander]

The slot in the top shelf of the receiver is .155 + .005"

The slot under the pin bolster, where the spring and plunger are, is .167 + .010", (not +/-)

The width of the catch itself is .150 +/-.003"

[Leaveammoforme]

Thanks for the info guys. That's why 'unknown origin' prints are labeled as such.