Minimag Drop off

[187skiers]

Hey guys im new here. So i havent played pb in about 6-7 yrs. I cleaned my gun out last night and took it to a shop today to see if it still worked. It worked fine, no leaks, but when firing fast it had some major drop off. the first shot started at 295, second 280, and by the third, the chrono said 260. Is there some thing I need to adjust or fiddle with???

[questionful]

Were you using CO2 or air? How fast were you shooting? What temperature was it? Try flipping the spring pack around.

[187skiers]

Compressed air, maybe 4-5 balls per second, room temp - maybe 67 degrees.

What does flipping the spring do?

[questionful]

I think you have it in backwards. Same thing happened to me once.

[SchoolU101]

I didn't think it made a difference which end of a spring went in first. Both ends are capped.

[michbich]

Is your spring longer than the bolt when they are assembled?

[187skiers]

Is your spring longer than the bolt when they are assembled?

Yes but not by much. Can I just pull on the spring to make it longer? Or is that not a permanent solution?

[athomas]

Replace the bolt spring. If it is weak it will slow down the bolt return and cause you to short stroke. This will cause velocity issues or coughing.

Pulling the spring will make it longer, but it will still be weak and will quickly return to its shorter size after just a couple of shots. Bolt springs are a consumable item on mags and should be changed on a regular basis anyway.

[187skiers]

thanks for clarifying. So how often should I swap it out? Also where can I get bolt springs now?

[athomas]

There's no hard and fast time for swapping bolt springs. In the early years of the mag, users used to put new bolt springs in for every tournament. I had over 50000 rounds fired before I had any issues with my level 10 bolt spring. Compression over time also weakens the bolt spring. If you notice it having issues, change it. If not don't worry.

[mr doo doo]

187skiers, drop me a PM, will be glad to send you a couple .

[lediable]

Just a thought, but along the lines of getting a new spring... If it has been that long since you played, you may just want to get a parts kit. Odds are there will be some o-rings that need replaced. Maybe not right now, but after playing a couple times. And of course in the parts kit is a new spring, solving that problem as well as being a bit of preventative maintenance.

I did the same thing, didn't play for 5-6 years, finally decided I had the $ and time again, oiled up my classic RT and had no probs the first two times out, then a banjo bolt oring went bad.

[SkinnyHare]

another thing to consider if you're running a reg in the front is that perhaps you have the output PSI on that dialed in too low. when i first got my minimag years and years ago i was using one of the old Sheridan RG-1 regs in the vertical asa as a secondary reg/foregrip... mostly as a foregrip because it was a perfect size for me... and had the exact same problem until i cranked it's psi output up.

[187skiers]

Thanks for the help. It makes more sense now, cause I havent fired the gun in about 6-7 years so the spring is probably pretty compressed. I have a grip in front but its just a gas through, not a regulator(good idea though Skinny). I'll send you a pm doo doo, I appreciate it.

[longi]

You could also try changing the piston o ring in the valve reg. Unscrew the velocity adjustster and pull out the brass piston with the smallest screw driver you can find, then change te o ring and put it all back together.