.38 Special case variation puzzle!

Status
Not open for further replies.
R

rcmodel

Member in memoriam
Joined
Sep 17, 2007
Messages
59,074
Location
Eastern KS
I have been fighting a 20% DA misfire rate with the Colt Commando since I bought it in October.
It works 100% in SA.

Original thread:
http://www.thehighroad.org/showthread.php?t=551464&highlight=colt+commando

Misfires: (FP strikes are not as far off center as they appear in the photo)
38misfireJPG.jpg

First, I found a cracked original mainspring, and replaced it with an aftermarket mainspring of unknown pedigree.
Still misfired about 1 in 6, but the DA pull was Sweet!

Then, I found a burr under the extracter star holding it up off the cylinder enough to cushon the FP blows.
Still misfired, but maybe not as bad.

Then I swapped another original Colt mainspring from my buddies Commando.
Still misfires, but only occasionally, about 1 every 12 rounds..

I tore the gun down twice since, and could find nothing at all out of spec as far as end shake, B/C gap, headspace, firing pin protrusion, hammer block interference, etc.

I had been testing with old mixed case reloads I had around for a long time. They work perfectly in a bakers dozen S&W J, K and N-frame .38’s & .357’s over the years, so I had no reason to suspect they were bad reloads.

Finally, after the last frustrating range trip, I got to putting 2 & 2 together and came up with 4, instead of the numbers I had been getting.

SAAMI max rim thickness is 059”.
Loads I had been testing rim variation:
Super-Vel = All .057” rim.
W-W = .056" to .057” rim.
R-P = .051" to .056" rim.
RA-67 = .051” to .053" rim.

Primer pocket depth range:
Super-Vel = All .119”.
W-W = .117” - .119".
R-P = .116”. - .118"
RA-67 = .117” - .121"!

The last three misfires were all in the RA-67 cases with the thin rims and deep primer pockets.
Primer seating depth was .005”, .006”, and .008” below flush!
Unfired GI RA-67 loads are .002" below flush, so they must have used taller primers then my CCI SP.

I had previously thought a .38 case was a .38 case.
But they are obvously not! :banghead:

It seems these RA-67 cases that worked perfectly for 40 years in every S&W I have owned since 1968 will just not work in the Colt Commando for whatever reason.

rc
 
Last edited:
As you found out, there is a tremendous amount of variance in rim thickness on different brands of .38 Special brass. That's why revolvers in that caliber over the years have had such heavy hammer springs. You'll find some that are paper thin, and then others that are pretty thick. PMC brass comes to mind, as well as Federal.

At least you figured it out. I'd hate to see you cross over into the New Year with that problem hanging over you.......

Happy New Year,

Fred
 
Yep!
The crazy thing is, I knew that.
If someone had posted the misfire question on THR, I would have suggested right from the get-go they try to narrow it down to maybe one brand of brass causing the problem.

But in this case, I had it stuck in my head it had to be a gun problem, cause the same mixed brass loads had always worked fine in my S&W's.

Never intered my mind it could be a combination of tolerance stacking of the thin rims and deep primer pockets in the R-P & RA-67 brass!

Pretty stupid of me not to take what would have been my own advice to others!!

At this point, I can only assume that all my S&W's over the years just hit them harder & deeper then this old Colt Commando.

rc
 
Last edited:
rc - don't sweat it, it happens to me too.

I'm a computer geek & there have been times when my pc is acting up.
(same situation as you) if someone else would've called me, I would've told them to do this & that.

But because it was mine, I couldn't think of the solution.
 
Just tested the gun again the other day with three different primers.

50+ rounds each with Win, Rem, and Fed primers, and it is 100% DA with all three.

It just won't light CCI primers all the time DA in these RA-67 cases.

Even CCI primers are fine in Winchester cases.

rc
 
Last edited:
Very interesting indeed.

It reminds me of an episode about 3 years ago. A buddy of mine bought about 2000 rounds of .38 Special factory ammo made by Magtech. His plan was to shoot them all up and then use the brass for all his reloading. He invited me to shoot with him one day to use up more of the factory ammo. I recall that when shooting my S&W J frame, I had a whole slew of misfires in DA. That was the only revolver that didn't like them. That revolver haas a very sweet DA pull also, and we just assumed that the mainspring "must have been" lightened by a previous owner and that the Magtech primers "must be" a bit harder. But as you point out, there's more to it than just weak springs or harder primer cups.
 
just a question. why does it fire 100% in SA and not DA? hammer not coming all the way back in DA, or something?

murf
 
why does it fire 100% in SA and not DA? hammer not coming all the way back in DA, or something?
Click to expand...

Correct - the hammer doesn't come all the way back in DA, since the trigger breaks earlier in DA than in SA.

50+ rounds each with Win, Rem, and Fed primers, and it is 100% DA with all three.

It just won't light CCI primers all the time DA in these RA-67 cases.

Even CCI primers are fine in Winchester cases.
Click to expand...

Would it make a difference if the CCI primers are hand-seated in the RA-67 case? I could make an argument either way that this might help or hurt reliability, so I'm curious what the data show.
 
They were hand seated in all the cases.

I use an RCBS hand priming tool for all my primer seating.

Basically, all the brands were seated the same way with the same equipment.

rc
 
They were hand seated in all the cases.

I use an RCBS hand priming tool for all my primer seating.

Basically, all the brands were seated the same way with the same equipment.

rc
 
Been there, done that.

Stripped and cleaned and lubed with Rem-Oil & GunSlick grease in all the right places.
I also tightened the slop in the hammer block linkage and removed manufacturing burs to make absolutely sure it is always getting out of the way of the hammer and hammer fall is free & not draggin on the frame.

I didn't replace the firing pin though, as the firing pin protrusion is already longer then my friends Commando by about .003".
I even have his mainspring in it now.

Already checked end-shake, headspace, firing pin protrusion, hammer travel in DA & SA, etc., and everything is in spec, or better then his gun as near as I can measure it.

rc
 
just saw you replaced main spring with your buddy's. this is getting interesting.

murf
 
how about this: fire one round SA and one round DA. compare the firing pin strike craters on the primer. do it again on your buddy's gun. see if there is a difference between the two guns.

murf
 
The firing pin mark will show a little, but isn't conclusive evidence of spring tension. There's a reason for that. When a primer detonates, it moves back out of the primer pocket and stops when it hits the recoil plate of the revolver. Then when the powder ignites, the pressure from the burning powder forces the case to the rear, reseating the primer. If the firing pin is still forward when this occurs, it will reimprint the primer cup.

This is what physically occurs when the round goes off, and of course there are other factors to consider as well. These include the charge of powder, size of the chamber, friction within the chamber, etc.

Just something else to consider.

Hope this helps.

Fred
 
+1
You can't tell a thing from looking at the fired primers.

As Fred pointed out, when they fire, they back out and form themselves around the protruding FP, then get re-seated when the fired case slams back against the recoil shield.
So the ones that fire look perfectly fine.

It's only the ones that don't fire that still show light hits.

rc
 
I have pulled my hair out trying to figure this one out with my S&W 66. I did everything you did to try and resolve the problem, and had better reliability, but still not 100%. I ordered an extended firing pin from Midway and a factory replacement main spring, and was still not getting 100%. Now after looking the problem over from the hammer, I found the hammer was actualy in need of a fine lapping, .002" lapped of the stop and it is now 101% reliable. SA delivers a longer drop on the firing pin which gives adequate energy to drive the firing pin hard enough. But DA isn't as long a drop so your getting reduced energy from the hammer and need a little more of the firing pin to drive. It's a tricky process because if you lap too much of the hammer you'll be carying a revlver that can discharge when dropped. But if your careful there is nothing to worry about. Just don't take it off more tha .001 at a time and load a bunch of primed only cases to test with as you lap.
 
I got 5 or 6 Colt Police Positives from police surplus from AIM for $80/ea for destructive tests.
But I really have fell in love with them.

Some of them have mis fires in double action.
So I take off the side plate and tweak the hammer spring.
Then they fire in double action.
 

Attachments

  • ColtPolicePosSpecialCutFrameRemedChamberDSCF3401smallerblankedss.jpg
    ColtPolicePosSpecialCutFrameRemedChamberDSCF3401smallerblankedss.jpg
    43.3 KB · Views: 108
why does it fire 100% in SA and not DA? hammer not coming all the way back in DA, or something?
Click to expand...
I have noticed this with some Colt DA revolvers, in DA the hammer doesn't travel very far.
How's the firing pin ?
 
So I take off the side plate and tweak the hammer spring.
Click to expand...
I considered doing that too.

But, original Colt Commando forged mainspring replacements are about as hard to find as unicorns.

I'm afraid to tweak it cause I might break it.

rc
 
I tweaked one and it worked great.

The next one with a problem, I think I broke the spring on tweaking it.

But I had another revolver that was blown up, so I cannibalized it, and tweaked that part.

If I am reading this right, and it is correct, then a V shaped hammer spring should go in and work:

http://thefiringline.com/forums/showthread.php?t=73953

Now I see that Commando means the old ones with the frame hump over the trigger.

When my youngest brother was in high school he made a flintlock. He made the V springs by bending flat spring steel. Then he heated it red hot and dropped it in oil to harden it. To temper it he put it in a tuna can full of oil, set it on fire, and let it burn itself out.
 
Status
Not open for further replies.

Similar threads

J
  • Locked
First .38 reloads. Lots of misfires
Replies
18
Views
953
rcmodel
R
B
  • Locked
What primer depth should I look for with 38 special?
2
Replies
30
Views
2K
.38 Special
.38 Special
K
  • Locked
plastic cased .38 Special
Replies
12
Views
935
GooseGestapo
GooseGestapo
joneb
  • Locked
"Missfire, kill the the SOB"
Replies
23
Views
1K
oldreloader
oldreloader
T
  • Locked
Old model Charter Arms Undercover .38 misfiring--again.
Replies
10
Views
3K
tbeb
T
Back
Top