Speed Cycling and reliability mod for Baikal MP-153

There is always that one particular brand, type or batch of shotgun ammunition that does not work with semiauto shotguns. Some shotguns are more picky than others and even same shotgun models some individual guns cycle same ammunition that other guns struggle with.

For DIY person it’s tempting to fix this uncertainty. Naturally lapping the bolt carrier rails, polishing all metal-to-metal contacts will help the gun to cycle. With gas operated shotguns drilling gas ports slightly larger might also help.

After doing all above I still found that there exists ammunition that does not cycle reliably with my Baikal MP-153.  Mostly really old 24g skeet and trap ammunition. Some may ask that why bother? Those asking that question don’t get the tickling sensation when fixing something makes things better.

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Phillips head screw mod to roller cam pin

Some time ago I acquired a roller cam pin to my AR-15. Gas key had to be machined to match the new round cam pin, but that was not an issue as I had planned to give my bolt carrier some diet in a form of tender milling from my trusted gunsmith. (Final weight for bolt carrier is 173 g.)

My roller cam pin had one problem though. The screw that was supposed to hold the brass roller in place had a tendency to loosen up and then jamming itself against gas key.

talvi_sra_2016_IMG_3694_bulging_roller-cam-pin
Roller cam pin screw loosen up and hitting gas key. Effectively preventing bolt from opening.

Original screw was completely flat, without any screw drives. I did not had adequate tools and strong enough thread lock to hold the screw in tightly.

roller_orig

I contacted the roller cam pin manufacturer and they offered to fix it for me. They apparently have some adhesive to semi-permanently attach the screw to rest of the cam pin.
I, being more of an DIY-guy, opted to fix the roller cam pin myself.
After two iterations I was finally happy with the solution.

ph2rollerr
Custom made phillips head screw for roller cam pin.

It may not be the best possible steel strength for this particular application, but the brass roller leans against small bulge in the cam pin, so the screw don’t have to take any force coming from side. It just has to hold the roller in place and avoid any contact with gas key.

luisti

Time: 1 hour
Tools used: one random M4 screw, hand-file, cordless drill, hacksaw, PH2 head screwdriver and “Extra hard thread lock”

Talvi SRA 2016 gallery

Some pictures from V-S Suomen Talvi SRA, a local reservist 3gun match.