Pump Problem

[El Camino]

I built a MM body, Classic valve, AM/MM rail pump marker. The problem is it resets its self. I've replaced the sear, stretched the wave washer. I'm using a gold spring and cut down blue bumper. Is my velocity too high??

[Ando]

I built a MM body, Classic valve, AM/MM rail pump marker. The problem is it resets its self. I've replaced the sear, stretched the wave washer. I'm using a gold spring and cut down blue bumper. Is my velocity too high??

Your problem is your bolt spring is doing it's job. Cut the spring down to where it's flushed with the bolt. Worn bolt springs are excellent for pump mags.

[XM15]

Ando is right the problem is your bolt main spring. The wave spring will be over powered by the bolt spring if its to strong. The lightest pump stroke and best trigger feel is when you weaken the bolt main spring just enough that it doesn't over power the wave spring. If you don't happen to have used spring that works just take maybe 1/8 of a coil off at a time until you get it consistantly not over powering the wave spring.

[El Camino]

Your problem is your bolt spring is doing it's job. Cut the spring down to where it's flushed with the bolt. Worn bolt springs are excellent for pump mags.

Thank you! I've got a good assortment of some used springs, I'll start with them!!

[El Camino]

Thanks guys, the spring did the job!!

[DaveA]

I chopped down my spring enough to stop recatching the sear, but it was less than the length of the bolt, so I began having intermittent chopping problems. I was able to stretch and bend the spring so it didn't add much real strength, but made contact with the internal body and this seems to have alleviated the chopping. But now it seems to shoot perfectly. I got a lighter return spring and chopped it down, placed a very small light one in the front of the pump sleeve, and moved the sleeve out a 1/32d inch to make up for the spring, and now the front return spring resets the pump handle to make for 1/4" pump stroke!