Why I won't mess with strain screws

[stantheman86]

Long story short, I bought a beater security trade in 15-7 about a year ago, but haven't really played around with it until now.The strain screw was pretty much destroyed it was so buggered, but the gun worked. I figured I'd file some off the screw, instant FTF on the first round.

I put in a brand new "domed" RB strain screw I bought for another gun, it made the DA pull too heavy and the SA break heavy as well. So, I had a used stainless strain screw that was already "mushroomed" from use and put it in, works perfectly. If it works, it works I guess, but now I see how filing just a hair off the strain screw can mess the gun up.

It shoots especially well in SA, I was looking for an all purpose range gun. After I dial in the sights I should be good, just hope the stainless strain screw doesn't mushroom any more and cause light strikes. I'm thinking of putting an old set of Pachmayr Presentation grips on it, somehow the Compac grips made for concealment don't seem right but I just put them on there to see how they worked.

 

[629shooter]

Every time I have had light primer strikes with a S&W, it was due to someone else "adjusting" the strain screw.

 

[k22fan]

Hello Stan.

I don’t shorten strain screws. Mostly I’ve left them turned in all the way but when I’ve backed them out for a lighter pull none ever moved on their own. The main spring acts like a lock washer. If you buy a used S&W that needs a longer strain screw for a temporary fix you can clean an old primer cup then put it over the end of the screw.

I see you are continuing to build your collection of 4” mid frame revolvers. That looks like a nice 15. The only Pachmayrs I like are the Compact Professionals. All the others add to much length to the trigger reach.

 

[H Richard]

A loose strain screw can and will back out with use. I was at an "industry showing", and S&W reps had several for use by all the writers. I was helping out as a range officer. A Precision Center Jerry Miculek 625 started misfiring, (it had a wonderfully light trigger that everyone loved). S&W rep set it aside to not be shot. I offered to look at it for him, and he just shrugged, so I pulled the stocks and the strain screw was backed out, nearly a full turn. The gun had had a master action job, so when the screw backed out it made it unreliable. I tightened up the screw and they used it the rest of the day.

 

[ROK]

I posted this in the lounge yesterday->

I had a squib .357 load today, my first.

Load was 17.5 grains of H110, Starline .357 brass, Extreme 125 grain FP and a Winchester small pistol Magnum primer.
I did not notice any difference in sound, but no recoil.
The gun was frozen. Cylinder would not rotate, trigger was fixed. I didn't know what was happening.
Was able to get the cylinder open finally, after seeing no gap between the forcing cone and the cylinder. Got the cylinder released, and tapped it open..I thought the ejector rod had become loose or unscrewed...

Bullet was just past the cylinder and stuck in the forcing cone.
Shell casing had a glob of partially burned, plasticized powder. Looked like foam from a cheap cushion.
The primer looked odd, almost like a light strike.

Too much happening here that I don't understand.
The unburned powder tells of incomplete combustion. Bad primer or bad crimp.
I lean to not enough crimp. Operator error rather than a bad component.
Came home and read of other crimp-light charge H110 issues. From what I read, H110 is best at or very near max levels, not the lower end of it's thin range where I had loaded it.

I used a light crimp on this load. Much lighter than I usually do. Plated bullets and all.

----------------------

Update->
I found what I think caused the problem.
The strain screw on the mainspring had backed out almost 2 full turns. I removed the grips to clean, as I always do, and checked the screw.
That explains the possible light strike (odd looking primer strike), because IT WAS A LIGHT STRIKE. I was just lucky it didn't happen earlier.
Took the screw out and cleaned the screw and screw hole with brake cleaner. Dried and Blue lok-tite.

I think I got it.

 

[k22fan]

I may have to agree to disagree with 2 posters.

Richard,

For the 35 to 40 years that I have gone to gun shows it has been common for vendors who have less than idea morals to back out S&W revolver strain screws before putting them out for sale. That’s why along with dry snapping a used S&W revolver you hold the trigger back while pulling the hammer back to feel how much main spring tension is on it. I see nothing in what your story to make me believe one of the salesmen had not backed out the strain screw so you writers would give the 625 or its Master Action Job glowing reviews. You did not write there was a starting point from which the strain screw rotated itself back away from.

ROK,

Although to prevent injury from hang fires gun safety classes still prudently advise keeping a gun pointed in a safe direction and not opening its action for 30 seconds after a missfire, hang fires caused by modern primers are very rare. Generally modern primers either ignite or they don’t. The only hang fires I’ve seen were in black powder muzzle loaders and only a few cases like yours in which the powder did not burn. I had a similar failure to burn only once with reloads. That occurred with every cartridge in a small batch of 7.5x55MM Swiss using Hornady’s H 380 powder. My other 3 or 4 contemporary reloading manuals gave starting loads that were higher than Hornady’s maximum. Using the data out of any of my other reloading manuals solved the problem. When I first loaded H110 in .44 magnum in1974 all my loading manuals warned that if Win. 296 and H110 were loaded below the starting load they would not develop enough pressure to burn resulting in hang fires. That has not changed. The obvious explanation for the H110 not burning in one of your .357 reloads is that you did not get enough powder in the case. Whether or not your strain screw rotated on its own there is no connection between your light primer strike and your H 110 only partially burning.

Both of you,

I have never had a strain screw that was not turned in all the way rotate on its own. Perhaps if S&W strain screws are backed out until the revolver will only fire reliably SA or in DA only reliably fire Federal primers there is not enough spring pressure left on the screw for the main spring to act as a lock washer. I wouldn’t know that because I always intended all of my S&Ws to be reliable in DA with all brands of primers. Otherwise, nothing either of you wrote leads me to believe strain screws that do not have their head pressed against the frame rotate on their own. I’ll read anything else you write to convince me but I suspect we may have to agree to disagree on this.

 

[k22fan]

Stan,

I’ve been hoping to get a chance to ask you how uncommon my fixed sight blued 4” full lug .38 special GP 100 is. Other than on the internet it is the only one I have seen. The salesman’s story was that it was made for prison system of security company but I doubt he actually knew. Anyway, with your interest in surplus 4” .38s and .357s I thought you might have an idea.

BTW, Ruger used the metal that normally protects the sides of adjustable sights to create the deepest fixed rear notch I’ve ever seen. Post WWII Colt DA fixed sights were easier to see than S&W and now Ruger has them both beat.

 

[Andyd]

K22 fan,

I have a Ruger GP100 with fixed sights in stainless. It was some police/security guard overrun but is still available from Ruger and is listed at Davidsons'.

I had more than one handfire in 8x57 IS surplus ammo. The Romanian ammo was notoriously bad with a one second delay every now and then. With a .303 Enflied, I had one hangfire of over 20 seconds that just ignited when I turned the bolt handle. Back in the day I got 1,000 rounds of 8x57 from Paragon for about $70 shipped in .50 cal ammo cans...

 

[stantheman86]

K22 fan, I have one of the full lug 4" blue fixed sight .38 GP100's, I got it in 2009 or so. It was some kind of trade in that was hardly carried or fired, it was from some sporting goods store in NM. They don't seem to be common, I haven't seen another one since. I also have the same gun in half lug. I just liked how the full lug .38 looked so I got one, and at the time I had a few other GP's. That .38 full lug is still one of my favorite guns, it has a heavy but a sweet, smooth DA pull. All of the later production Service and Speed Six revolvers, and the fixed sight GP's have that nice deep rear sight notch and Ruger does a good job regulating the sights. Unless you need to fine tune the sights for precision accuracy with a handload, those fixed sight GP's will serve you just fine and they'll last forever.

I want one of the new fixed sight 4" stainless .38 GP's, I have one of those adjustable sight .38 GP's from Davidsons and it's an excellent gun, I wanted the fixed sight to go with it.

 

[k22fan]

Andyd,

Thanks for bring up hang fires in old military surplus ammo. I hadn’t thought about that in quite a while. In the 1980s surplus 238 grain spitzer 8mm Lebel was sold dirt cheap still loaded in Hotchkiss machine gun loading strips. The stuff misfired about every 3rd shot in all the half dozen rifles that I saw it fired in. IIRC there were hang fires mixed in with the missfires. Fired in a Berthier (? Spelling) carbine it kicked worse than a .460 Weatherby. If I scratch my memory I’ll probable remember other batches of surplus that had hang fires. However I still maintain hang fires caused by primers that were purchased in recent years are rare. Just about all instructors training students for modern action pistol type matches or self defense ignore the possibility of hang fires. They teach an immediate tap-rap-bang response after a pistol doesn’t go bang. That’s not prudent if you think about it.

 

[GaryS]

Timely thread. As I posted in my "Model 13 at the Range" thread here, I had three FTF out of 100 38 Special WWB rounds. The gun is used and has a very nice trigger pull.

Is it normal for a strain screw problem to only cause three misfires or is likely to be the ammunition? Two of the rounds fired on the second strike, one was moved to my 642 and fired.

 

[LEO918]

About half the S&W revolvers I buy have the strain screw backed out some.