Protocall_Design
Member
I wouldn't worry about .001 of hammer shim. Just run with the .002. It will be fine.
Normal Hammer block contact? Model 36
- Thread starter Matt_X
- Start date
Sure. Moving the front edge of that hammer seat back a bit more may just solve the problem. I can't think of anything else that would cause these kinds of inconsistent primer strikes. The integrity of the hammer nose and the hammer nose bushing have been confirmed. There's really nothing else in the pathway of the hammer at this point.
Carter
Carter
Took that leading corner of the rebound back a bit yesterday evening.
This morning I thought it would not hurt ot further investigate the hammer nose and the shims. Since there still is a little contact favoring the right side of the hammer and hammer nose, why not.
Hammer freedom was compared with the main spring removed.
Swapping to the .003" hammer shim revealed a little bit of friction as the hammer completes its forward motion. Hardly noticible but not worth the risk.
Hammer nose has freedom of movement in the full forward (firing) position. But there was a little roughnous depending on if it touched a little to the left side.
So (a) very lightly stoned the nose circumfrance on the left to radiuse the corners and smooth the ridges.
(b) filed the rough contact visible on the left side of the frame cavity. Probably could do more there.
The action sounded snappy with snap caps, but that's fooled me before. I ran a piece of aluminum foil behind the dummy cartidges and the punchs look OK (but don't know if that proves anything). I'll report back when I get to a range and test it for real.
This morning I thought it would not hurt ot further investigate the hammer nose and the shims. Since there still is a little contact favoring the right side of the hammer and hammer nose, why not.
Hammer freedom was compared with the main spring removed.
Swapping to the .003" hammer shim revealed a little bit of friction as the hammer completes its forward motion. Hardly noticible but not worth the risk.
Hammer nose has freedom of movement in the full forward (firing) position. But there was a little roughnous depending on if it touched a little to the left side.
So (a) very lightly stoned the nose circumfrance on the left to radiuse the corners and smooth the ridges.
(b) filed the rough contact visible on the left side of the frame cavity. Probably could do more there.
The action sounded snappy with snap caps, but that's fooled me before. I ran a piece of aluminum foil behind the dummy cartidges and the punchs look OK (but don't know if that proves anything). I'll report back when I get to a range and test it for real.
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Not quite there yet.
First three cylinders fired without a hitch which was an improvment.
Fourth cylinder had the first failure on first strike double action.
It fire on second strike, also double action.
The misfire was after a slow trigger pull - not quite two stage but close enough I thought it could be a contributor.
But then there was a failure to fire every 5 to 10 rounds after that. Grand total of 4 failures to fire on the first pull out of 40 with Fiocchi, and 1 failure to fire on the first strike with 15 or so Precision One 125 gr FMJ. Used up the rest of both boxes with a Victory with no hitches.
First three cylinders fired without a hitch which was an improvment.
Fourth cylinder had the first failure on first strike double action.
It fire on second strike, also double action.
The misfire was after a slow trigger pull - not quite two stage but close enough I thought it could be a contributor.
But then there was a failure to fire every 5 to 10 rounds after that. Grand total of 4 failures to fire on the first pull out of 40 with Fiocchi, and 1 failure to fire on the first strike with 15 or so Precision One 125 gr FMJ. Used up the rest of both boxes with a Victory with no hitches.
Protocall_Design
Member
Have you ever checked to see how far the hammer nose sticks out of the recoil shield with the hammer all the way down? It should be around .050, about the thickness of a dime. Variations in rim thickness, primer seating depth, endshake, etc, can become a problem if there is not enough protrusion.
Yes. Firing pin protrusion is around .044 or .045" (comparing with feeler gages). Khunhausen wrote that he has measured .039 to .048" so it seems one is close to factroy maximum. (He also suggests .055 to .062 max should be good, but I infer that is if one is replacing the nose).p.79 5th edition
I just finished cleaning the cylinders and bore, so will take a look at the internals in a bit.
A little frustrating not being able to find a pattern.
Maybe I can check the main spring's force using a weight and wire coathanger?
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Were you pulling the trigger forcefully and completely to the rear during you double action pulls? An "incomplete" trigger pull can result in the rebound slide not being fully retracted.
Consequently, the rebound interferes with the hammer's full forward motion and impetus. The result is light hits on the primer.
Carter
Consequently, the rebound interferes with the hammer's full forward motion and impetus. The result is light hits on the primer.
Carter
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I beleive so but did not focus on that, which I should have after that first FTF.
After all this did come up earlier in the thread.As mentioned about I did catch myself pulling the trigger slowly when taking a more difficult shot. But it fired fine. It was the following shot that was the FTF. I'll have to pay more attention to whether I am short cycling the trigger.
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Protocall_Design
Member
How fast you pull the trigger makes no difference in the hammer fall. The hammer is always released at the same point regardless of how it got there. If the mechanism is correct, the rebound slide will be far enough back when the hammer comes off the trigger. Maybe if the trigger pull is just barely enough, the rebound spring might move it forward a bit as the hammer is falling.
Short stroking the trigger is when you don't let it return quite all the way and it locks up the action until it does go all the way forward.
Short stroking the trigger is when you don't let it return quite all the way and it locks up the action until it does go all the way forward.
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With the sideplate plate off and main spring out, moving the trigger to the point it will just release its close but seems the hammer can be moved forward to contact the frame before hitting the rebound. Still, I'll have to make a note to be sure to pull the trigger all the way to the the trigger guard just to be sure I'm not causing the problem as you describe.
Thank you for explaining that.
Three places where Dykem rubbed off:
Upper right leading edge of the hammer to the side plate.
Right side top of the hammer block.
Hammer nose - mostly right side.
Upper right leading edge of the hammer to the side plate.
Right side top of the hammer block.
Hammer nose - mostly right side.
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The rub mark on the sideplate indicated with an arrow is from the front leg of the bolt.
Carter
Carter
Checked the main spring force on the hammer as shown here.
https://smith-wessonforum.com/141763281-post12.html
It's a little different than Kuhnhausen but makes more sense to me.
Just about 3.5#
I used a coat hanger, milk jug with water, and postal scale.
https://smith-wessonforum.com/141763281-post12.html
It's a little different than Kuhnhausen but makes more sense to me.
Just about 3.5#
I used a coat hanger, milk jug with water, and postal scale.
Protocall_Design
Member
That's 56 ounces. With Federal or Winchester primers you would probably be OK. With your ammo (primers), you probably need to be in the 64 to 70 ounce range.
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Of course I had to recheck my measurements after you posted that.
3# 12 oz lifting very slowly the hammer held.
3# 13 oz. and it did not.
So 62 oz.
Right below what you're saying is needed for consistancy with the harder primers. But close enough makes me hopeful that a new factory spring might do the trick.
I didn't check before I took the Precision One to the range with me as an alternative to the Fiocchi. Yep They use CCI primers.
Protocall_Design
Member
CCI and Remington are the hardest primers. I don't know how all the foreign primers rate.
Finally got to do a little testing at the range.
So far, so good double action with
20 rounds Browning 130 gr FMJ
20 rounds Remington 158 gr LRN
Dykem is still on the right side of the hammer (did not get scraped off).
Next test will be the Fiocchi or Precision One with the harder primers.
So far, so good double action with
20 rounds Browning 130 gr FMJ
20 rounds Remington 158 gr LRN
Dykem is still on the right side of the hammer (did not get scraped off).
Next test will be the Fiocchi or Precision One with the harder primers.
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and with the Fiocchi 158 gr FMJ the failures to fire returned.
Most of today's shooting was single action as I was checking point of impact vs point of aim for 10, 16, and 25 yards. First 5 DA were fine. But there was a failure to fire on the first hammer hit for a cartridge in each of the 3 cylinders fired double action at the end. Second hit they fired.
Based on the hammer spring check above, it seems the most likely cause and solution will be a factory hammer spring.
Most of today's shooting was single action as I was checking point of impact vs point of aim for 10, 16, and 25 yards. First 5 DA were fine. But there was a failure to fire on the first hammer hit for a cartridge in each of the 3 cylinders fired double action at the end. Second hit they fired.
Based on the hammer spring check above, it seems the most likely cause and solution will be a factory hammer spring.
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I've read through this thread with great interest and am hopeful that a new, full power hammer spring takes care of it. If you PM me your address, I'll send you one.
ETA: grammar improvement
ETA: grammar improvement
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