Gunsmithing Sear/Extraction Timing & Cocking Piece Handoff

[vvillium3]

Good Afternoon All,

Curiosity has gotten the best of me recently, and I started wondering why some custom actions are inherently smoother than others during bolt close/open. Machining tolerances, spring rates, and action/bolt type aside (let’s just assume similar design). Is one of the biggest factors in smoothness, the timing between the cocking piece hand off to the trigger sear bar & the extraction cam? Is there an ideal point to hand off the cocking piece in relation to the extraction? Because the extraction happens for a longer duration than the cocking release, is there a general guideline to follow is degrees of rotation?

I’m sure that I’m over thinking this, but I know there is a reason some actions come with trigger hangers to better time this. As well as fixtures to help time the handle better when being soldered on. Let me know if I’m way off on this one.

Thanks,
Jason

 

[Sonic Crack]

Cocking does effect how smooth the bolt close feels. Also how the bolt meets the angles leading into the lug abutments. Excesive over cocking can be taken care of to improve feel. Ive been told that you want at least 1/4" of firing pin drop for good ignition.

 

[Turd in the Pool]

The extraction cam should only come into play when you are extracting. Trigger hangers are mainly to make closing easier/smoother.

I fought a camming issue a while back. Turned out the guy that installed the bolt handle missed what was kicking my ass too. Hate to name the bolt maker but I'd bet you can guess.

The engaging corner of the lugs were square. They should have a slight 45 deg. angle on them. Each bolt/ rec. combo is unique so finding an ideal handoff point is unique.

 

[Aeon1]

Trigger hangers came about so you could remove a trigger from a glue in without the hassle of removing trigger cross-pins and getting them realigned to put the trigger back in not to mention cross-drilling stocks properly to get to the pins. Offset hangers came about when people realized the variances in triggers as far as pin fall was concerned. Many started using the offset hangers to move the triggers to improve cocking feel but then many noticed their rifles would not shoot consistently. If you reduce pin fall too much on a rifle it may suffer inconsistent ignition. BAT will give you recommended pin fall specs as well as Kelbly's. Kelbly's bases their design on Remington research during the Mike Walker era. Kelbly's has done a fair amount of testing triggers and pin fall as it relates to ignition. You may get away with less fall but not always. In short it's a trade off. I prefer to do everything I can to insure good consistent ignition rather than a smoother cocking mechanism. There are ways to improve cocking feel without reducing pin fall. As you alluded to materials and heat treat have a lot to do with how smooth things can be made as well.

 

[vvillium3]

Trigger hangers came about so you could remove a trigger from a glue in without the hassle of removing trigger cross-pins and getting them realigned to put the trigger back in not to mention cross-drilling stocks properly to get to the pins. Offset hangers came about when people realized the variances in triggers as far as pin fall was concerned. Many started using the offset hangers to move the triggers to improve cocking feel but then many noticed their rifles would not shoot consistently. If you reduce pin fall too much on a rifle it may suffer inconsistent ignition. BAT will give you recommended pin fall specs as well as Kelbly's. Kelbly's bases their design on Remington research during the Mike Walker era. Kelbly's has done a fair amount of testing triggers and pin fall as it relates to ignition. You may get away with less fall but not always. In short it's a trade off. I prefer to do everything I can to insure good consistent ignition rather than a smoother cocking mechanism. There are ways to improve cocking feel without reducing pin fall. As you alluded to materials and heat treat have a lot to do with how smooth things can be made as well.

Aeon,

Thanks for the great response. I just couldn't get my head around the angle timing between sear handoff while the bolt was moving forward on the extraction cam. But in reality, it's just down to the spring tension fighting back during closing & cocking.

Thanks Again,
Jason