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1/25/2018 7:38:29 AM
Posted: 2/7/2006 6:17:52 AM EST
[Last Edit: 2/7/2006 7:08:52 AM EST by TravisJ1]
I have a Colt MarkIV, series 80, government model in 9mm.
It wont relaibly cycle 115 grain ammo. This is just a range gun, and 115 is what I like for plinking, without this turning into a ammo debate, I need to know what size/weight lbs. the spring is.

I want to put in a lighter spring, but was hopeing to still be able to shoot 124 grn.

Any suggestions?

Need to know what weight I have......

What weight should I drop down to......

Thanks everyone,


Editte­d for spelling
Link Posted: 2/7/2006 6:55:32 AM EST
What won't cycle? The slide doesn't come back far enough? The ejecting casing gets hung up? What's the failure?

And the word you're searching for is "lighter" :)
Link Posted: 2/7/2006 7:01:44 AM EST

Originally Posted By Evil_Ed:
What won't cycle? The slide doesn't come back far enough? The ejecting casing gets hung up? What's the failure?

And the word you're searching for is "lighter" :)


Yeah it dosen't allways eject, or if it does eject, it won't feed the new round corectly. I had a smith look at it, and he says nothing wrong with gun, it's the ammo.

So we tested that theory, and sure enough 124 or heavier cycles fine, 115 is questionable. But like I said I like 115 for plinking/cost, and want my gun to work with all ammo, not be picky, know what I mean?


Link Posted: 2/7/2006 7:05:48 AM EST
Another thing, if I cycle the gun by hand, it ejects and feeds fine.

So I don't think it is a ejector/extractor problem?


Where's Hobbs?
Link Posted: 2/7/2006 8:04:13 AM EST
[Last Edit: 2/7/2006 8:04:49 AM EST by Evil_Ed]
There are two springs that work on that...the primary (believe it or not) is the trigger hammer spring in the main spring housing, in the grip. When the slide moves back, that's the first thing it has to overcome; re-cocking the hammer. The recoil spring doesnt really come into play until the end of the cycle, when it's just about compressed and starts to push the slide forward.

So, you can do one of two things...optimally you would tune them together...

You can go to a lighter hammer spring as option number 1...pretty easy to do if you have three hands, or some kind of vise. Just compress the hammer strut plug, pop out the retaining pin, and SLOWLY let the cup come out. This thing is under a lot of tension, so if you don't push the cup down and slowly let it up, it WILL take your eye out and/or get lost

You can also check your main recoil spring...it should be a 16# spring. If it is and it's still too much, try a 14# spring...I would _not_, under any circumstances, go below a 12# spring. Colt Gold Cups come with them stock, and they're meant for light handloads purely for the racegun folks. Realistically you shouldn't need to go below a a 15# spring, really.

Failing that...stick with 124's

Edited cause I typed trigger when I meant hammer...
Link Posted: 2/7/2006 8:39:53 AM EST
Ok if I change the hammer spring, do they have weight ratings? What weight should I go to?

Thanks Evil Ed,

Link Posted: 2/7/2006 9:02:47 AM EST
[Last Edit: 2/7/2006 9:04:03 AM EST by Evil_Ed]
Your best bet would be to check with Brownell's, or Numerich...I don't know the spring weight off the top of my head but I know most tuning kits include a new one, which purports to lighten trigger pull..

ETA Here you go:

Link to Brownell's hammer spring items
Link Posted: 2/7/2006 9:31:32 AM EST
Thanks Ed.

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