While we often hear much about 'bolt timing', seldom do we ever get to see an example of this. While there's a lot involved in this whole issue, much of it is subtle in nature and hard to describe without having the pieces in hand and saying: "See????!!!! That......right there! 
So with all that said, I'm going to put up a couple of pics showing how one specific bolt timing issue was resolved on an action. A little background is in order, I suppose. This action had always been a troublesome unit for it's owner since new. Despite minimal bolt-to-reciever clearance, when the bolt was cocked the bolt shroud and cocking piece would raise upward. The pin tip showed evidence of damage that initially was thought to be caused by the pin tip being retracted behind the bolt face, thus being dinged up as it bounced through the pin hole when the pin came foward. Despite these maladies, the rifle actually shot pretty well although never up to it's owners satisfaction. But it did show promise at times.
Several attempts were made to correct the 'jack up' issue with the shroud and cocking piece...lowering the trigger, a new trigger hanger, several new cocking pieces and some reworking of the cocking piece/sear engagement angle, new firing pin, shroud...you name it, it was tried. And still the issues remained...bolt shroud/cocking piece 'jack up' when cocked and firing pin damage finally culminating in the bolt handle coming loose.
The action finally made it's way into Stan Ware's hands at SGR Custom Rifles where the problem was identified. What was happening was that the locking lugs on the bolt weren't clearing the locking lug abuttments in the reciever before the root of the bolt handle was 'coming up' on the cocking cam angle machined into the reciever. When the bolt was closed, the cam angle on the bolt handle was 'camming' while the bolt lugs were firmly seated against the lug abuttments in the reciever...and since the cam angle on the handle rotated upward as it closed, this caused the cocking cam to raise upward along with the bolt shround. Because of the angles involved, all this happened during the last small amount of bolt closeure, making diagnosing this virtually impossible externally. Essentially, the original bolt handle was just a bit too far foward. By how much...I have no idea.
The original bolt handle did all it's camming on the small leading edge of the bolt handle. It also had the added benefit of a screw attaching it to the bolt body as well as the handle being silver soldered to the bolt body. Because of the 'jamming' that happened between the cam angle on the bolt handle and bolt lugs when the bolt was either opened or closed, the cam angle on the handle exerted tremendous force on the handle itself..in effect trying to rotate the handle around it's axis (the screw) which it finally did when the silver solder failed.
Picture #1 shows the original handle (bottom) and the new PTG handle installed by Stan. Stan recut the cam angle on the PTG handle to work with the angle on the reciever. This new handle spreads the camming load out over a much great area than the original...where the entire camming force was concentrated on the small leading edge of the root of the bolt handle.
[/IMG]
Picture #2 shows the cam angle on the reciever. If you look closely, you can see a small mark...this is where the 'jamming' was occuring.
[/IMG]
Picture #3 shows the cam angle interface between the reciever and the new bolt handle. Notice that Stan has kept a 'tail' on the bolt handle that wraps as far around the bolt body as possible. This, along with eliminating the bolt handle screw, almost doubles the surface contact area between the bolt handle and the bolt body for more silver solder area.
[/IMG]
Picture #4 shows another view of the cam angle interface.
[/IMG]
After the rework, the bolt shroud/cocking cam 'jack up' is gone. The original trigger hanger positions the trigger perfectly in relation to the cocking cam and sear. And finally....no more pin tip damage. What was initially thought to be damage caused by the pin tip being retracted behind the bolt face (and bouncing through it as the pin came foward causing the damage) was in reality the pin tip being 'tweaked' and slightly bent in the pin hole as the cocking piece was levered upward due to the bolt handle/locking lug being 'out of time' with each other.
Certainly there is a lot more involved with the whole topic of 'bolt timing' but hopefully this is of some help. When you get into an area like this, you really need to have someone with true 'gunsmith' or engineering skills to help sort this stuff out.
Hopefully this will start some discussion about 'bolt timing' and related issues. There are actions out there that have a history of never shooting well..no matter how many barrels they've had installed or how many scopes have been on or how many times they've been restocked. Maybe they're suffering from some timing issues and can be straightened out? I know that in conversations with some really good 'engineering type' gurus in the accuracy rifle business..they have all said that bolt timing is an area where occasionally an individual example of an otherwise fine custom action may not live up to their potential.
Looking foward to hearing your thoughts and ideas.
Good shootin'. -Al
So with all that said, I'm going to put up a couple of pics showing how one specific bolt timing issue was resolved on an action. A little background is in order, I suppose. This action had always been a troublesome unit for it's owner since new. Despite minimal bolt-to-reciever clearance, when the bolt was cocked the bolt shroud and cocking piece would raise upward. The pin tip showed evidence of damage that initially was thought to be caused by the pin tip being retracted behind the bolt face, thus being dinged up as it bounced through the pin hole when the pin came foward. Despite these maladies, the rifle actually shot pretty well although never up to it's owners satisfaction. But it did show promise at times.
Several attempts were made to correct the 'jack up' issue with the shroud and cocking piece...lowering the trigger, a new trigger hanger, several new cocking pieces and some reworking of the cocking piece/sear engagement angle, new firing pin, shroud...you name it, it was tried. And still the issues remained...bolt shroud/cocking piece 'jack up' when cocked and firing pin damage finally culminating in the bolt handle coming loose.
The action finally made it's way into Stan Ware's hands at SGR Custom Rifles where the problem was identified. What was happening was that the locking lugs on the bolt weren't clearing the locking lug abuttments in the reciever before the root of the bolt handle was 'coming up' on the cocking cam angle machined into the reciever. When the bolt was closed, the cam angle on the bolt handle was 'camming' while the bolt lugs were firmly seated against the lug abuttments in the reciever...and since the cam angle on the handle rotated upward as it closed, this caused the cocking cam to raise upward along with the bolt shround. Because of the angles involved, all this happened during the last small amount of bolt closeure, making diagnosing this virtually impossible externally. Essentially, the original bolt handle was just a bit too far foward. By how much...I have no idea.
The original bolt handle did all it's camming on the small leading edge of the bolt handle. It also had the added benefit of a screw attaching it to the bolt body as well as the handle being silver soldered to the bolt body. Because of the 'jamming' that happened between the cam angle on the bolt handle and bolt lugs when the bolt was either opened or closed, the cam angle on the handle exerted tremendous force on the handle itself..in effect trying to rotate the handle around it's axis (the screw) which it finally did when the silver solder failed.
Picture #1 shows the original handle (bottom) and the new PTG handle installed by Stan. Stan recut the cam angle on the PTG handle to work with the angle on the reciever. This new handle spreads the camming load out over a much great area than the original...where the entire camming force was concentrated on the small leading edge of the root of the bolt handle.
Picture #2 shows the cam angle on the reciever. If you look closely, you can see a small mark...this is where the 'jamming' was occuring.
Picture #3 shows the cam angle interface between the reciever and the new bolt handle. Notice that Stan has kept a 'tail' on the bolt handle that wraps as far around the bolt body as possible. This, along with eliminating the bolt handle screw, almost doubles the surface contact area between the bolt handle and the bolt body for more silver solder area.
Picture #4 shows another view of the cam angle interface.
After the rework, the bolt shroud/cocking cam 'jack up' is gone.
The original trigger hanger positions the trigger perfectly in relation to the cocking cam and sear. And finally....no more pin tip damage. What was initially thought to be damage caused by the pin tip being retracted behind the bolt face (and bouncing through it as the pin came foward causing the damage) was in reality the pin tip being 'tweaked' and slightly bent in the pin hole as the cocking piece was levered upward due to the bolt handle/locking lug being 'out of time' with each other.Certainly there is a lot more involved with the whole topic of 'bolt timing' but hopefully this is of some help. When you get into an area like this, you really need to have someone with true 'gunsmith' or engineering skills to help sort this stuff out.
Hopefully this will start some discussion about 'bolt timing' and related issues. There are actions out there that have a history of never shooting well..no matter how many barrels they've had installed or how many scopes have been on or how many times they've been restocked. Maybe they're suffering from some timing issues and can be straightened out? I know that in conversations with some really good 'engineering type' gurus in the accuracy rifle business..they have all said that bolt timing is an area where occasionally an individual example of an otherwise fine custom action may not live up to their potential.
Looking foward to hearing your thoughts and ideas.
Good shootin'. -Al
Last edited:
