What is meant by the term "throw by" and what is the cause ?

[M. De Land]

I've heard 45D and perhaps one or two more folks use this term and think I know what it means but would like to have it described and explained so I can learn more.

 

[SDSmlf]

I've heard 45D and perhaps one or two more folks use this term and think I know what it means but would like to have it described and explained so I can learn more.

When the cylinder rotates past the bolt and isn’t locked up correctly.

 

[M. De Land]

When the cylinder rotates past the bolt and isn’t locked up correctly.

Oh, bolt hop from a late drop or buggered notch ? Wonder how that happens with a lead cut that is marked up? I've not experienced the problem that I'm aware of.
Must have been common with Walkers and Pattersons having no lead cuts.

 

[SDSmlf]

Oh, bolt hop from a late drop or buggered notch ? Wonder how that happens with a lead cut that is marked up? I've not experienced the problem that I'm aware of.
Must have been common with Walkers and Pattersons having no lead cuts.

No expert here, but yes…. I’ve seen it happen from late drop, usually on out of tune or cheaper DA guns being worked fast. I’ve also seen it on C&B guns from the leading edge of the notch getting peened over to the point that the bolt couldn’t enter the notch, always speculating it was because of the soft steel the C&B cylinders were manufactured from. I’ve not seen peen notches on cylinders made for modern CF guns, with the takeaway being that the cylinders were made from proper modern gun steel.

Above is speculation on my part based on observation. Let’s see what the experts have to say.

 

[45D]

Oh, bolt hop from a late drop or buggered notch ? Wonder how that happens with a lead cut that is marked up? I've not experienced the problem that I'm aware of.
Must have been common with Walkers and Pattersons having no lead cuts.

Yes, "bolt hop" or "bounce"(Colt parlance) CAN happen when bolt drop happens too close to the notch. It's purely a physics thing.
It is common if folks decide to "fan" their SA, with no "attention", out of the box. Most Italian reproductions have late bolt drop and when subjected to "fanning" or "fast handling" (cowboy shooting) . . . it won't handle it.
With correct timing (per Colts) - Walkers, Dragoons even Remingtons ( obviously not Colts) without "lead cuts" (approaches would be Colts parlance) can in fact be fanned.

In fact, I saw this post as I sat down to supper and decided to go through some of my revolvers with a "fanning" test ( its been a while ). So, tested were a Pietta 1873 copy, a 1st Mod Dragoon, a Remington and 2 Ruger Old Armys. All were loaded with dummy rounds and fanned (not just cocked with an open hand but actually fanned like the competition shooters) and all did perfectly fine with no throw-by. The approaches add some assurances but it isn't a "must have". All have the 4 lb bolt tension (rather than the 8/9 lb you get from the factory) and my upgraded hand spring and pushrod for enhanced "frame mounted" (Ruger type) hand spring set up.
The Factory "check list" lists the first check be for a cracked or broken or mis-adjusted hand spring . . . mainly because it's the job of a correctly set action that the hand "retard" cyl rotation for lockup. Its been the contention of some that the bolt dragging on the cylinder is responsible for "braking" for lockup but as far as Factory build specs / rebuild instruction, and Custom Shop employees, it is in fact the job of the hand to ready the cyl for lockup.

Obviously, if a bolt spring is broken or compromised, you wouldn't have lockup at all. Throw-by may NOT happen if the action is cycled slowly but with "normal" or anything more aggressive than that may in fact have Throw-by consequences.

Mike

 

[JimCunn]

I've got throwby when fast thumbcocking an older Uberti 1862 Police.
In my case, it seems to be a combination of a very draggy bolt and a weak, well-used bolt spring. Bending the handspring for more force and facing the worn top of the hand helped a little, but I've got a new hand assembly and bolt spring on the way, and am going to do a bit of internal polishing when I install them. The old ones are still serviceable, so will go in the parts bin.

 

[M. De Land]

I've got throwby when fast thumbcocking an older Uberti 1862 Police.
In my case, it seems to be a combination of a very draggy bolt and a weak, well-used bolt spring. Bending the handspring for more force and facing the worn top of the hand helped a little, but I've got a new hand assembly and bolt spring on the way, and am going to do a bit of internal polishing when I install them. The old ones are still serviceable, so will go in the parts bin.

I've had to ratchet file both my original cylinder and the new one I fit to the my 62 Uberti to get them to function correctly. It seems to me that the five point ratchet star having a sharper angle for the hand to engage and traverse the teeth in the lift cycle is geometrically less smooth than is the six point star and thus more fussy about the contact angles.
This is aggravated by a longer stroke the hand has to make with five teeth instead of six in proportion to the cylinder diameter.

 

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It can also happen on big kickers like the .454 Casull in Freedom Arms. Recoil can cause it.

 

[SDSmlf]

It can also happen on big kickers like the .454 Casull in Freedom Arms. Recoil can cause it.

Curious that recoil from big kickers would cause the bolt to drop/disengage allowing the cylinder to ‘throw by’ or over rotate the next time a single action revolver was cocked after being fired. Recoil memory maybe? Could you possibly provide some documented examples of this occurring? First I’ve ever heard of recoil causing the event, and do own, shoot and reload for a number of ‘big kicker’ type handguns we don’t discuss here.

 

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No I cant, just personal experience.

 

[SDSmlf]

No I cant, just personal experience.

So you have had one or more of Dick’s guns ‘throw by’ from recoil? I still have a few factory special order ones from the 1980s, all of which are still bank vault tight and tighter than any other handgun I have owned, with never a hint of ‘throw by’. I’ll drop off here as this is outside the scope of the forum rules, but having dealt with the man personally before he passed, a problem like you describe would have been resolved immediately. No need to answer, but surprised the problem wasn’t corrected. Topic for a different forum.

 

[[email protected]]

So you have had one or more of Dick’s guns ‘throw by’ from recoil? I still have a few factory special order ones from the 1980s, all of which are still bank vault tight and tighter than any other handgun I have owned, with never a hint of ‘throw by’. I’ll drop off here as this is outside the scope of the forum rules, but having dealt with the man personally before he passed, a problem like you describe would have been resolved immediately. No need to answer, but surprised the problem wasn’t corrected. Topic for a different forum.

Only one and it was corrected. Another term was used, not throw by, but cant remember now what it was, it was about 20 years ago.