Can you shim a (coil) Mainspring to get harder hammer strike? (RIA .38 Snub)

[John in WI]

A while back I picked up a Rock Island .38 snubby. It seems to work fine with all the (standard pressure) commercial ammo I ran through it. Unfortunately, I'm getting occasional misfires with handloads. I'm using Fiocchi primers (newly purchased). I was going to blame the primers, but I just borrowed a friend's Ruger .38, and ran 30 through it, and they fire no problem with his revolver.

I read up on it, and it seems that RIA revolvers can suffer from weak hammer strikes. I haven't been able to find a heavier main spring (although I read main springs for Colts will fit). I was just curious if I could put a couple of small washers under the existing spring, and if that would give it a little more "oomph"? I can't think of a reason why it would be a bad idea (safety wise, at least).

Has anyone else had a similar experience with the RIA? It seems to be solidly built. Not finely finished, but rugged.

[Texas by God]

If the mainspring strut has a capture pin hole it will help.
I want to do that on a Taurus PT22 auto- but I haven’t figured out how yet due to no spring capture feature…..


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[HWooldridge]

One or two washers should help. You just don’t want to hit the fully compressed length and crush it.

[John in WI]

The "capture pin" is the hole at the bottom of the rod. Where you cock the hammer, insert a paperclip, and then let the hammer down? It does have one of those. I have a couple of small stainless washers, and was thinking I could maybe shim it 1-2mm and give it a try. Failing that, maybe order a heavier Colt main spring.

I was surprised that this was a problem--the primers appear to have a healthy dent in them. It's maybe just a fraction of a millimeter off center, but the impacts are deep. Anyway, as I mentioned, the Ruger eats the reloads no problem. It's something goofy with the Rock Island.

[TD1886]

If the mainspring strut has a capture pin hole it will help.
I want to do that on a Taurus PT22 auto- but I haven’t figured out how yet due to no spring capture feature…..


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Make a capture hole with a very small Cobalt drill bit.

[country gent]

Light hits can be caused by tight rough areas dragging also. It may not be a light spring but a tight binding area in the action

[36g]

Light hits can be caused by tight rough areas dragging also. It may not be a light spring but a tight binding area in the action

Excellent observation. Disassemble, take a magic marker and mark all surfaces of the hammer. Dry fire a few cylinders worth and disassemble. Note any wear marks and where appropriate polish with 600 grit sandpaper.

[John in WI]

Hmm. I never thought about something dragging/hanging. When I got it I took off the side plate and lubricated the action. But there are some machine marks that are pretty obvious in there. I'll have a look at it and see. I have some Dykem that would work great to look for anything scraping. I also have some 800 and 1200 grit paper left over from a painting project. I could make it like a mirror if I needed to.

[36g]

While you have it apart, check for any burrs either inside the frame or on the inside of the side plate and in the vicinity of the pivot pin for the hammer. A review of the disassembly video on YouTube showed some wear marks on the nose of the hammer indicating a pinch point between the hammer nose and the slot in the frame in the recoil shield area. Not saying that yours is similar but it's worth taking a look there.

[John in WI]

There look to be a few spots where the parkerizing is worn. The part of the hammer below the spur has a wear mark on it.

Should I just use a small sanding block and some 800 grit, and give it a bit of polish? I don't want to chew up the parkerizing too badly. Especially not where the finish will be exposed and visible from the outside.

[ohen cepel]

Dry fire it a lot as that may solve the issue.
Most revolvers could benefit from a little polishing.

Could call Wolffe Springs to see if they have a spring for it, if needed, after doing the above.

[schutzen-jager]

old gunsmith trick - put tight fitting nail or hardened steel rod in spring - on hard surface tap entire length of spring with hammer while rotating it - this wil strech it + give same effect of adding washers - polishing the bearing surfaces of action would help performance in several ways -

[36g]

There look to be a few spots where the parkerizing is worn. The part of the hammer below the spur has a wear mark on it.

Should I just use a small sanding block and some 800 grit, and give it a bit of polish? I don't want to chew up the parkerizing too badly. Especially not where the finish will be exposed and visible from the outside.

If the parkerizing is a black oxide, a small spot can just be hit with gun blue (like Brownells Oxpho Blue) to cover up the polished area. I'd suggest to take a sanding block (or other flat surface) attach a piece of 600-800 grit paper to it, then set that on a firm surface. Move the hammer over the paper controlling the flatness of the hammer surface to the surface of the paper and controlling the area desired to be polished. I've found it easier to control the part to be polished easier that trying to control the larger sanding block.

[TD1886]

I polish the strut going through the center of the spring and sometimes I'll carefully polish the inside of the spring.

[rintinglen]

Back in the day, department armorers used to test the hammer strength by suspending a 3 1/4 # weight from the hammer and slowly lifting the gun by the barrel. If the hammer moved, the mainspring was too light, so either the strain screw would be tightened or the main spring replaced. In some cases, a spent primer with the anvil removed would be used to shim the strain screw to slightly increase the tension on the spring and thereby repair the light hammer fall.

There is a video showing how to disassemble the RIA 206 on youtube.

[schutzen-jager]

i've only seen strain screws on flat spring models + not on any coil spring variety i am aware of -

[rintinglen]

@ schutzen-jager, You are correct, sir.

I meant to describe the means of testing a spring's strength, but was not clear, or rather, I was incomplete in expression, in how that pertained to the problem at hand. An old man's rambling, I guess. But what I was trying to imply was that the OP can certainly use a small washer to pre-compress the RIA Mainspring to increase the hammer fall's force. It will function in the same fashion as the spent primer I was alluding to in my recollection. And I doubt that it will take a washer more than 2 or 3 mm thick to do it.

[DougGuy]

It looks like you could swap in a Ruger single action hammer spring.

[Baltimoreed]

I had lightened my .45 ruger vaquero hammer springs years ago to be more competitive but with having to use SRP instead of SPP I started getting light strikes. I added a spacer, i had polished the hammer strut when I clipped the coils. Polish things then add a spacer or buy a new spring.