Stripped sr-1022 rail threads

*MALICE*

*MALICE*

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My buddy stripped the screw holes (6-48) in his SR1022 receiver (holes that the rail gets screwed to in the top of the receiver)

Being that I'm his favourite machinist, he asked me to fix it.

Since this is a reasonably common problem, I figured I'd go with the reasonably common solution of redrilling/tapping to 8-40. I'd have to buy the tap and screws, likely less than $50 for the tap and screws to my door.

But....at work, I have an M4x0.7 (~36.25tpi) helicoil kit, helicoils, and M4 screws. So this repair would cost nothing if I went that route.

Any reason the M4 helicoil kit isn't the way to go? The receiver is cast aluminum, so the stainless steel helicoils should be stronger with way less chance of stripping the holes again compared to directly threading the receiver to 8-40.

And considering the top of the receiver is approximately 3/16" thick, the effective difference in maximum amount of threads is ~3/4 of a thread between M4 and 8-40.

Anything I'm not considering?
 
It seems to me it would work... and install the screws with blue Loctite and tell your buddy to quit f##kin with them.
 
I've used the helicoils on a few stripped out aluminum threads. Mostly automotive application, so we're talking larger bolts/threads. The threads are definitely stronger than the aluminum ones and have lasted many years - have never stripped any helicoil threads. Not tried it on a gun though - didn't know they had them that small. If you have enough room to re-tap and set a helicoil in the receiver - seems to me to be the way to go. Good luck.
 
*MALICE* said:
My buddy stripped the screw holes (6-48) in his SR1022 receiver (holes that the rail gets screwed to in the top of the receiver)

Being that I'm his favourite machinist, he asked me to fix it.

Since this is a reasonably common problem, I figured I'd go with the reasonably common solution of redrilling/tapping to 8-40. I'd have to buy the tap and screws, likely less than $50 for the tap and screws to my door.

But....at work, I have an M4x0.7 (~36.25tpi) helicoil kit, helicoils, and M4 screws. So this repair would cost nothing if I went that route.

Any reason the M4 helicoil kit isn't the way to go? The receiver is cast aluminum, so the stainless steel helicoils should be stronger with way less chance of stripping the holes again compared to directly threading the receiver to 8-40.

And considering the top of the receiver is approximately 3/16" thick, the effective difference in maximum amount of threads is ~3/4 of a thread between M4 and 8-40.

Anything I'm not considering?
Click to expand...

I'd be leery of the pitch difference when tapping out the holes with the Helicoil Tap. But if the threads will clean up, it's a cheap fix. Sorta like Tattoos, you can always go bigger and uglier!

Dunno. I'd be looking at having the guy buy the parts and tooling in exchange for the fix.
 
Brownells's still sells the oversized screws and taps for 6-48 which would work. Maybe a local smith would have some on hand for such instances.
 
trevj said:
I'd be leery of the pitch difference when tapping out the holes with the Helicoil Tap. But if the threads will clean up, it's a cheap fix. Sorta like Tattoos, you can always go bigger and uglier!

Dunno. I'd be looking at having the guy buy the parts and tooling in exchange for the fix.
Click to expand...

The m4 helicoil drill will completely clean out the 6-48 threads so no worries there. And i have the helicoil kit/helicoils/and m4 screw so the fix would cost nothing
 
guntech said:
40 tpi is better than 48 tpi in aluminum.
Click to expand...

Size for size, finer threads are "stronger" than course threads. Although fine threads are more prone to damage, fouling, and galling.
Course threads are more "durable" though.

However, being that it's cast aluminum the difference in strength would be marginal (i think)
 
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