Need Help with Misfiring Ruger P-90 .45 ACP

[Mainer]

I originally posted this in the Ruger Firearms section, but didn't get any replies so I'm giving it a shot here:

I've had a P-90 for a number of years.  For the past three it has been sitting in the gun cabinet because it was misfiring--i.e., a couple of rounds from each magazine would require two hammer strikes to fire.  It has been a while, but I think I recall seeing light firing pin strikes on most/all of the primers.

Is this due to a worn out main spring?  If so, is it a DIY job, or should I send it to the factory or take it to a gun smith?

FYI: I have been kind to this gun, firing almost exclusively standard velocity ammo--and only a box or two of +P (although it should be tough enough to take a lot of +P).

Also, my first P-90 was replaced by the factory because it had a rough spot on the bottom of the barrel under the chamber that was grinding away at the frame.  This P-90 (the factory replacement) has gone back to the factory as well--for repair of the magazine catch which fell out of the gun at the range.

[Mikey]

Mainer - I would simply get yourself something that works, all the time.  JMHO.  Mikey.

[Mainer]

I hadn't thought of trading this gun in.  I had been fond of it: accurate, excellent trigger pull.

But maybe you're right; it would constitute a sizeable downpayment on the .44 Mag I want.

Still, I would like to fix it before it winds up in someone else's hands.

So back to my original questions:

(1) Is this likely a mainspring problem;

(2) If so, is replacing the mainspring a DIY job;

(3) If so, how do I do it.

Thanks.

[Savage]

Mainer,
What you have is a pistol in need of new springs. Nothing to it, order yourself a set of springs and fix that thing! You own a hell of a pistol! No snob appeal, but they are highly underrated for the money. You would be hard pressed to trade it for anything better, without paying a lot more.
Savage

[poncaguy]

Call Ruger, they'll probably fix it free. I have a P90, P95 and  the   new P345..........never any problems with them, great pistols for the money.

[Mainer]

I figured out how to change the hammer spring. :grin:   It's easy.

(1) Make certain the gun is unloaded.

(2) Remove the grip panels.

(3) Push out the small pin at the bottom of the grip frame (no hammering is required, the pin just pushes out).  I think I used a 1/8" punch.

(4) Pull the plastic hammer spring seat out of the bottom of the grip frame and the hammer spring and hammer strut will fall out of the bottom of the gun.

(5) For reassembly, the hammer strut should be inserted in the grip frame so the bend in the hammer strut faces toward the rear of the gun.

Here is a diagram of a disassembled P-90: http://www.e-gunparts.com/productschem.asp?chrMasterModel=1910zP90D

Replacement hammer springs are available from either Numrich Gun Parts Corp. www.e-gunparts.com or Wolff Gunsprings: http://www.gunsprings.com

By the way, I highly recommend the 16lb Wolff recoil spring in this gun.  It greatly reduces recoil over the factory 11lb recoil spring, yet the gun still functions 100% and still hurls spent cases quite far.

[Abearir]

I too have .45 P90DC that does the same thing. However my problem is a result of a dirty chamber. When it gets the slightest bit dirty, the chambered round doesn't go competely into battery. I suspect, you have the same problem. At least with mine the problem is amplified by using lead loads, the bullet lube acts as a adhesive, and slows the round down too much before it fully chambers. I polished the chamber really well using a Dermal Tool, and it helped a lot.