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Ease of bolt lift after firing

Rocketvapor said:
I don't think I need to look into bushing the bolt head.
Pin measures 0.0687", bolt head passes a 0.072" (-) pin but not a 0.073"(-) pin.
View attachment 1561792

Pin fall is greater than a stock Savage Bolt. Pin cocking piece counterbored to shorten pin and increase pinfall. See previous picture of stock/modified pin.
View attachment 1561793
This required a little work on the cocking slot.

View attachment 1561794


The small parts shown in my previous post show a "New" style BAS, a 10mm Carbide micrometer tip, a 38cal mod with a Silicon Nitride ball (7/32" and 1/4" balls).
The bearing races are 10mm from ebay (not from a lift kit) and can be inserted under the micrometer tip to increase/decrease spring preload.
The Carbide tip in the new style BAS is 0.080" SHORT. I shaved down BAS length about 0.065". The 38SPL brass case/Ceramic ball can be made from a low of about 0.050" to about 0.090" giving a wide range of added internal preload.
View attachment 1561798View attachment 1561799

The spring is an EGW Commander flat wound spring with firing pin preload shortened by counterboring the cocking piece about 2 threads.
Click to expand...
What pound is the commander spring?
 
Shooter13 said:
Good point, maybe we can get @Alex Wheeler to school us some on this.
Click to expand...
Most of the bolt lift comes from the spring and cocking ramp design. Depending on the action and the era it was from will tell you a lot. Theres only so much you can do with a spring and you can only go so light before giving up accuracy. The cocking ramp itself plays a big role. Theres some tricks you can do to help smooth out the lift with the design. I have been cutting cocking ramps for a decade now and have tried a lot of different things with the helix. A straight consistent helix works but its not the best way. I shared some of that with Borden and you will notice a change in the helix on those bolts if you have been paying attention. Particularly at the top of the helix. The newer bolts open much better than the old straight helix bolts. This has been a while though, maybe 3 or 4 years now. Bats are the opposite. The old Bats had too shallow of a ramp to get much firing pin fall. I used to have to cut every one. I did get them to change the ramps maybs 5 or 6 years ago. But I still re cut my personal ones deeper yet and incorporate some of those designs because I prefer a lot of firing pin fall. The steeper ramp can actually open as good or better than a shallower one if its done right. Now my testing has been mostly all long range. The little involvement I have in short range has shown that in that game you can get away with less energy. The thing I have never seen hurt accuracy is too much firing pin fall and I prefer more than most from what I have seen. Not enough is a killer same with springs. However, the springs really have a relationship to the primer and are chosen accordingly. Still there is a minimum threshold. And all of this is based on a good clean ignition. They have to be gone through and all bind or drag eliminated. Depending on the action your comparing to, it may be that they open easier or it my be your technique. You should be able to roll open the bolt even with a heavy spring and not slow down much. You cant just grab the knob and lift. Push the shroud down and roll open the bolt with your fingers. I have some guys that complain about bolt lift and I have their stuff setup as low as I can without hurting anything and they still cant shoot as fast as some with 25+ springs that open far worse. So technique is huge. Now if your willing to live with cock on close then all that goes out the window and you can make them open real easy. Im not.
 
kris bassett said:
What pound is the commander spring?
Click to expand...

It's lighter, by a lot, than the stock Savage 28lb spring.
Probably too light to be used without shortening the pin by counterboring cocking piece (increases preload and pinfall) and shimming the preload up some more if needed. Watch out for the bottom of the slot when increasing pinfall of a Savage.
The 0.060" pin protrusion with the stock savage (Primer stops the pin before that anyway).costs some pinfall.
I shoot for just under 0.040". Some say you can go lower.

Savage wastes a lot of pinfall with decocking when moving from the cocking shelf/notch to sear hold. Lawyers must have designed the notch/bump :)
Mine seem to make the cocking jump just at the point the primary extraction ramp on the rear baffle engages.

When the wife and I go to the range to try out something I usually take two bolts, set up differently to try. What I like about the Carbide/Silicon ball bolt lift mod is I can pull the BAS and add or remove shims at the range.
Glad I got away from the new style firing pin, lift kits, and external washers.
I have a couple of Tubb springs to cut down from long action to short action but haven't done anything with them, yet.

EDIT 6/9/24: The spring I am currently using is an EGW Flat Wound spring for a Colt Commander, part # 10660, listed as 22#.
Using a single 10mm bearing race behind the Carbide Mic tip for a total internal increase in spring preload of about 0.120" (shim, and shortened pin) and about 0.060" increase in pinfall over a stock Savage bolt. Pin protrusion is about 0.038"

Just remember, I am NOT a GunSmith, just an experimenter.
Nice explanation Alex. Care to give away some secret stuff? :)
 
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Alex Wheeler said:
Most of the bolt lift comes from the spring and cocking ramp design. Depending on the action and the era it was from will tell you a lot. Theres only so much you can do with a spring and you can only go so light before giving up accuracy. The cocking ramp itself plays a big role. Theres some tricks you can do to help smooth out the lift with the design. I have been cutting cocking ramps for a decade now and have tried a lot of different things with the helix. A straight consistent helix works but its not the best way. I shared some of that with Borden and you will notice a change in the helix on those bolts if you have been paying attention. Particularly at the top of the helix. The newer bolts open much better than the old straight helix bolts. This has been a while though, maybe 3 or 4 years now. Bats are the opposite. The old Bats had too shallow of a ramp to get much firing pin fall. I used to have to cut every one. I did get them to change the ramps maybs 5 or 6 years ago. But I still re cut my personal ones deeper yet and incorporate some of those designs because I prefer a lot of firing pin fall. The steeper ramp can actually open as good or better than a shallower one if its done right. Now my testing has been mostly all long range. The little involvement I have in short range has shown that in that game you can get away with less energy. The thing I have never seen hurt accuracy is too much firing pin fall and I prefer more than most from what I have seen. Not enough is a killer same with springs. However, the springs really have a relationship to the primer and are chosen accordingly. Still there is a minimum threshold. And all of this is based on a good clean ignition. They have to be gone through and all bind or drag eliminated. Depending on the action your comparing to, it may be that they open easier or it my be your technique. You should be able to roll open the bolt even with a heavy spring and not slow down much. You cant just grab the knob and lift. Push the shroud down and roll open the bolt with your fingers. I have some guys that complain about bolt lift and I have their stuff setup as low as I can without hurting anything and they still cant shoot as fast as some with 25+ springs that open far worse. So technique is huge. Now if your willing to live with cock on close then all that goes out the window and you can make them open real easy. Im not.
Click to expand...
Thank you sir! That is a lot of information! Again, thanks
 
Thanks for the information guys, one thing...can you explain what you are talking about when you say pin fall? I am pretty good at trigger mods but have never messed with bolts. I actually like a cock on close bolt. Would love it if my rifle was a cock on close.
 
kris,
Pinfall is the distance that the pin falls from the position held by the sear to the position when hitting the decock pin stop (back of bolt head) or primer.
Impact energy delivered by the spring depends on spring force accelerating the pin and distance traveled (minus friction encountered as it falls).

When cocking a Savage over the notch, cocking force of the spring plus primary extraction (handle to rear baffle ramp) can add up at the handle. You'll FEEL this at the top of handle travel extracting a fired case.
Dropping the Shelf and Notch gets the pin cocked a little earlier.

Another comment,
I don't have to worry about voiding a warranty playing with the cocking ramp.
Worst that can happen is destroying a $40 bolt body.
 
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I see, that's what I figured it was just wanted to make sure. This is my cocking ramp which I'm sure is very typical of a savage. I do want to get one of pt&g oversized bolt bodies as mine has a lot of play in it.1000004233.jpg
 
GPalman said:
its al in the reamer specs and the diameter of the case .200" in front of the case head,.
Click to expand...
Greg, hummm, no. I can dry fire mine and still can't lift the bolt with ease, I can use my fingers but can't imagine doing it 100 to 150 times! I'd have a 3" callus on my finger! LOL
 
Shooter13 said:
Go here https://www.wheeleraccuracy.com/videos and click on "straight stocks track", I know he is promoting the stock tracking but watch the bolt as he fires and refires. Also watch "how smooth timed actions cycle"
Click to expand...
I agree with everything Alex said but I think the three biggest factors are brass, dies and pressure. I know you mentioned dry firing but those things are way bigger than any normal mechanical aspect of the actions. Another thing with that video is gun weight and stock width. Not sure about either specifically but I'd guss at least 17 lbs and 4 or more inches wide at the forearm. Those things go a long way toward making it look great as compared to a lighter, narrower gun.
 
Shooter13 said:
Go here https://www.wheeleraccuracy.com/videos and click on "straight stocks track", I know he is promoting the stock tracking but watch the bolt as he fires and refires. Also watch "how smooth timed actions cycle"
Click to expand...
Those are all old videos from when I still had a youtube channel. I used a lot of Pandas in those days. They were all recut to have .240" or more pin fall with no cock on close with the factory 21 pound spring. So I made them open a little harder to make them close better. So that Panda your watching opens more like a Borden. Which in my opinion is not a bad thing. Now with with better ramps and coatings they open even better. What you are seeing is technique. And that ramp is not a straight helix either. But a new Bat or Borden will open as good or better. If your struggling, have someone check it just to be sure you dont have an issue. Sometimes the cocking piece pin walks out and rubs inside the shroud. Aside from killing accuracy it will make opening hard. Check the wear pattern on the ramp as well. Thats a 17lb. 4" wide rifle fyi. The second video shows the timing which is all close. It opens easy because I didnt dry fire it. Timing is how they close. Thats what I was showing. And that run of timed dual port pandas I did with sako extractors before they would do a sako were to this day some of the smoothest actions I have ever had my hands on.
 
gunsandgunsmithing said:
I agree with everything Alex said but I think the three biggest factors are brass, dies and pressure. I know you mentioned dry firing but those things are way bigger than any normal mechanical aspect of the actions. Another thing with that video is gun weight and stock width. Not sure about either specifically but I'd guss at least 17 lbs and 4 or more inches wide at the forearm. Those things go a long way toward making it look great as compared to a lighter, narrower gun.
Click to expand...
Mike I agree all those things are contributing factors BUT this is a Borden action (BRMXD) and without a round in chamber I can dry fire and still have heavy bolt life, like Alex said there is a lot in technique I still can't get it to do anywhere close to what I see others do. My BAT M is the best I have as far as opening and closing.
 
You may be looking in the wrong area. You said this happens after firing so the problem may be in the lower area in the cartridge case. You may need to size the bottom of the case in addition to using an FL die. You may need a smaller based die.
 
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