Light Firing Pin Strikes on a Pre-27

[Peter M. Eick]

I have a very nice 8 3/8" pre-27 that has been heavily worked over by a gunsmith at some point in its history. When I got it, I am nearly positive it had never been fired beyond proofing or maybe 1 or 2 cylinder's full (if that). The trigger and hammer have been polished enough to remove the color of the case hardening, the action has been tuned and polished internally completely. The trigger pull is great, sub 2lbs in SA and 7 lbs in DA and crisp, really really crisp. The main spring has been "thinned and tapered" dramatically from the bottom to top.

Now the bad news. The side plate has been polished and the fitting edge was also polished thus there is a distinct gap around the sideplate to the main frame. The assembly numbers all match so I figured what the heck, it is a shooter. As a collector gun its value is shot, but as a shooter, what the heck!

Now the really bad news. This gun will not consistently set off CCI primers in SA mode let alone DA mode. After around 800 rounds, I am starting to get irritated. Yes the tensioning screw is tight if you are wondering and it appears to be the same length as my other pre-27's.


Some smith put a lot of effort into this gun and I hate to bugger it up, but I really enjoy shooting the 8 3/8" gun and it is the first one I have ever seen in pre-27 or Registered fashion.

So, do I replace the spring and call it good? Shim the tensioning screw or some other non-cosmetic change? Switch to Federal's for just this gun? Other ideas?

 

[Old Fuff]

First of all, be sure you don't have any cylinder end-shake (back and forth movement of the cylinder when it's latched, as opposed to rotational movement). A little end-shake can make a big difference when you also have lightened springs.

Using feeler gauges, measure the cylinder/barrel gap while holding the cylinder back as far as it will go. Then do the same while pushing it forward. Subtract the second reading from the first, and the result will indicate the end-shake, if any.

Also be sure there isn't any powder fouling between the extractor star, and its seat in the cylinder. This, in combination with end-shake will in effect move the cylinder forward, away from the firing pin.

If the double-action is truly 7 pounds you have no tolerance left - and must have maximum firing pin protrusion and impact.

 

[rmw]

If you have excessive headspace or endshake that could be the cause , also check the firing pin protrusion . If all of that looks ok and the DA pull is light then he probably just lightened the spring "file or belt sander" so you can tighten the strain screwall you want and you will never get enough tension

 

[ribbonstone]

Only reasons I can think of for the light strikes:
1. Mainspring is too light...as stated, could be a polished down spring or a replacement. Strain screw can be full length, but if the spring has been changed, it won't increase the tension enough.

2. Firing pin strike is short ..could be a gunk-build up or somthing else limiting the strike. Need to check the amount of pin protrusion.

3. Headspace (produced by end shake) .

4. With the over polishing you describe, could they have polished INSIDE the frame as well..and if they did, could the hammer have enough side-to-side play that the pin is striking along the side of the channel, dragging and slowing it's fall through the recoil shield?

5. Does the firing pin is supose to have a bit of up-down spring loaded "wiggle"..check to be sure it isn't jammed in place by gunk/rust/debris.
---
I had a brand new mod. 19 that missfired...eventaully i traced it down to the little tiny frame cut that model 19's are supose to have at the top fo the firing pin channel. Cut wasn't there..was on all the other 19's checked. Pin was tapping the frame as it moved forward, which robbed it of part of it's power.

 

[1911Tuner]

re:

Look at the strain screw itself to see if the end has been trimmed back. It should have an extension that's smaller than thread diameter. Some of the old smiths used to cut that off.

CCI primers are known for being tough to light. Try Winchester or Federal.

 

[LHB1]

Replace the mainspring (hammer spring) with a Wolff Reduced Power spring or Full Power spring. If gun still misfires, problem lies elsewhere as noted above. FWIW, I have/had at least eight S&W K, L, and N frame guns with Wolff Reduced Power mainsprings and no misfires in any with Win primers.

Good shooting and be safe.
LB

 

[HSMITH]

Peter, I do NOT believe in action jobs that require a certain primer for reliability. As Fuff mentioned that is SOOO sensitive that it doesn't take much of anything to have misfires. Take a spent primer cup and put it on the end of the strain screw, in between the screw and the spring and crank it down. Try it out. If it gets better we have a direction to take. A Wolf reduced power spring will keep you down with a light pull in DA, and should handle the CCI primers if the firing pin protrusion and all of that is OK. A standard power mainspring and a 12 pound rebound spring will still pull around 7 or 8 pounds DA (provided ALL of the action work was done well and correctly) and works fine in a target gun, if it won't light any and all primers there is something really wrong with the gun. All standard power springs in the gun with good action work should still pull 8 or 9 pounds and be dead smooth, it will be hard to tell it from a 7 pound pull on the range.

Thinning and tapering the mainspring is an old trick to lighten the spring for a reduced DA pull. It works, very well in fact, but it MUST be done just right or the spring is junk.

 

[1911Tuner]

Cup

HSMITH said:

>Take a spent primer cup and put it on the end of the strain screw, in between the screw and the spring and crank it down.<
****************

And I thought I was the only one who had done that little trick.
Used to do it on trimmed strain screws. Works, too!

 

[Old Fuff]

Take a spent primer cup and put it on the end of the strain screw, in between the screw and the spring and crank it down.

Yup, I've done that too...

But I don't think its the answer in this case...

Peter said...

Yes the tensioning screw is tight if you are wondering and it appears to be the same length as my other pre-27's.

 

[HSMITH]

Fuff, it is a pretty good cheat on a spring that got thinned out too far though also, gain a little smack on the stroke if you know what I mean....

 

[1911Tuner]

Cheatin'

Fuff, it is a pretty good cheat on a spring that got thinned out too far though also, gain a little smack on the stroke if you know what I mean....

If nothin' else, it's a pretty reliable way to test the mainspring. If the primer cup makes it go bang more reliably, it's probably the spring. If not, look elsewhere.

 

[Peter M. Eick]

Thanks guys, I was thinking along the same lines myself (that is a shim on the strain screw, but the primer cup is a great idea).

The gun has no endshake at all. None is measureable unless I really physically force the cylinder to move in the window. I probably should have noted that but I figured since I stated the gun was new, and it was a Pre-Numbered gun, that would go without saying.

Well, I guess it is time to pull out the strain screw, and find a large pistol primer (spent of course) and see what good that does. I have plans to go shooting this friday so I will let you know how it works.

By the way, have you all ever wondered why someone would buy a gun, get it smithed to high heaven for target shooting and then never once fire it? Its like the 38/44 Outdoorsman I picked up last years. 55 year old gun, never even had the cylinder turned. Weird.....

 

[Old Fuff]

Its like the 38/44 Outdoorsman I picked up last years. 55 year old gun, never even had the cylinder turned.

Some people just get lucky...