Savage bolt head dimensions,

J

Jay Idaho

Guest
Bill Leeper posted on another thread:
"Although this might be hijacking the thread to a certain extent, I'm going to do it anyway!
How much slop in the floating bolt head? Also, is the pin at 90 degrees to the locking lugs? The last bolt I made for a Remington, I started out to make a floating head. I then decided to fit everything closely instead. My thinking was, if the bolt body and bolt head are precisely made and fitted, they would be straight anyway. Nonetheless, I may make the next one to float."
I have one Savage bolt, several bolt heads and crosspins. The crosspins are about .244/245 diameter. The matching hole in the bolt head and bolt body are .250(bolt head)/.251(body) pin "go". The shank on the bolt head ranges from .461 to .464 diameter and the hole in the end of the bolt body is .469 pin "go".
The crosspin is 90º to the lugs.
Incorporating some semblance of "Borden bumps" on the bolt body should minimize vibrations.

Jay McMunn
 
I think the idea is to accurately size the case to fit the chamber and let the case head locate the bolt head with no induced stresses from too tight a fit between the bolt head and the bolt body. For a trued action there is probably no accuracy advantage from the Savage design. For an action that is not true then there could be accuracy gains to be had.

Maybe one should fit the Savage bolt head to tighter specs if he has a trued action.

Also, maybe putting some bumps only on the rear part of the bolt would be good to counteract the trigger effects while leaving the case head to locate the bolt head.
 
Not sure if there was a question but I am a big fan of the savage floating bolt head.

The floating head 'absorbs' alignment variances in the action/threads/barrel so that things still lock up tight and true. I get BR tight lock up and alignment without the costs. Both lugs must seat on the receiver.

There is little point in making a floating bolt head for a dead true BR type action. No slop to take care of.

I also see no point in putting borden bumps on a Savage bolt body. Yes, my bolt bodies move around when the sear is dropped. Quite visible actually.

But because the bolt head is floating, movement in the bolt body does not upset the bolt head lock up. The bolt head stays firmly seated against the receiver.

This has allowed me to get some very accurate rifles limited to barrel/bullet quality more then action. The accuracy is also retained at some elevated pressures - magnum pressures.

One nice thing about the floating bolt head is the firing pin hole must be enlarged. At pressures much beyond magnum (65/70,000psi), you will get primer cratering. No issues with extraction or accuracy but a sure fire way to know when things are getting toasty.

Works for me....

Jerry
 
Jerry, if you have bolt movement when you pull the trigger, you will also have rifle movement. It is this tiny amount of movement that top BR guys are wanting to reduce. Crank the magnification up to 45x or more and dry fire at a target, the crosshair will move and that means the rifle was not pointing at where it was supposed to be. This doesn't really apply to my shooting but it certainly does for many of the guys here.

In the Savage bolt head the firing pin is not in the firing pin hole until you pull the trigger. Along the inside of the bolt head body, the diameter is larger than at the face, the pin has a tremendous amount of float when cocked and does not when fired. The pin tip could actually hit this firing pin hole inside edge as it moves forwards, it is not tapered. If you remove the bolt assembly screw and allow the pin to protrude, you can hold it in place as you flip it back up by tilting the head to the side and as you release the head the assembly will fall out. This means the firing pin assembly has lots of room to float and the firing pin hole determines where that pin assembly is going to be centered. On the bolts I bushed, the head float remains the same but the pin bushing is deep so the firing pin assembly is guided all along. Initally I was worried about the firing pin stop alignment to the head but the threads allow the stop to straighten up when it hits the head.

To reduce or possibly stop cratering on a Savage in particular, the firing pin tip radius can be increased. Often the tip is too sharp and this promotes cratering where there should be none. Having a sharp tip and a oversized hole may tell nothing about pressure, except maybe when its too low.

I would like put "Borden Bumps" on my new Savage Dasher, but have so many irons in the fire right now its going out :D Maybe a little nubbie on the bottom of the bolt handle [90` when the handle is up] would do?

Cheers,
Rob
 
crb said:
Jerry,
We are putting Savage bolt heads onto Remington 700 bolts.
Click to expand...

How have the results been?

PEIRob, that is interesting on the bushing. I think the scope vibration is due more to the slamming of the firing pin then the bolt body moving. There is not much mass moving a small distance. The firing pin is hitting pretty hard.

Besides all that wiggly is factored into the very big boom that follows :D

I have used many actions and never found the cratering to be a problem. I have always hit magnum or slightly higher pressures before cratering occurs. That tells me I am in the right pressure range.

Accuracy is also usually the best when that starts.

Seems to work for me.

Jerry
 
Hi Rob,
If you are dry firing with no case or primer, the bolt & scope movement will be much greater than if a primer is in place.

Typical pin protrusion is about 0.060". Typical primer indent is more like 0.030". In the real world, the pin never slams into it's bottom seat. If the pin is not restrained/cushioned by the primer, the firing pin will slam into it's bottom seat with much more disturbance than if it is cushioned by the primer indent.

Regards,
Dave Russell

PEI Rob said:
Jerry, if you have bolt movement when you pull the trigger, you will also have rifle movement. It is this tiny amount of movement that top BR guys are wanting to reduce. Crank the magnification up to 45x or more and dry fire at a target, the crosshair will move and that means the rifle was not pointing at where it was supposed to be.
Rob
Click to expand...
 
Jay,
I was just looking at the only Savage bolt I have handy (from an old CIL 950T) and it doesn't appear to have near that much clearance on the bolt head to body fit but there is enough that it will move.
I don't know that there would be any advantage to installing bumps on the Savage bolt though I suppose it wouldn't hurt. Since the purpose of the bumps is to prevent misalignment from pressure on the cocking piece, and since the pressure on the cocking piece of the Savage is not transmitted to the bolt body, I dont see any advantage. On the other hand, floating bolthead or not, better alignment is never a bad thing. It would be fairly easy to make a replacement body that fit better
When I made the bolt up for my 40x, I made it to be more like a Remington bolt which was pinned together rather than soldered. In other words, the dimensions were much the same as the Remington bolthead. I also made the crosspin much larger (.375") so it would accomodate the Remington firing pin.
Rob may be onto something regarding the firing pin alignment. When I first disassembled the 950T bolt the firing pin tip was bent. There had to be a reason for that. Since the crosspin does move quite freely, it's possible the crosspin was misaligned and pushed the pin to the side. I might have to bush the bolt head tenon. Good call, Rob! Regards, Bill
 
Bob Brushingham said:
What would happen if you unsolderd a Remington bolt and machined some slop in it and installed a savage cross pin?
Bob
Click to expand...
A friend gave me a 700 bolt that he trashed (put the Sako cut on the wrong side!). I decided to take it apart to see "how it was made". Between the crosspin and the silver solder, it required a major effort. I can't imagine being able to take one apart and reassemble it in a satisfactory manner. Serious heat is required to melt the silver solder that was used by Remington.
A conversion to a Savage bolt head is a piece of cake compared to the above operation. Making your own bolt body is no big deal if you have a super spacer or similar tool available.
I would love to hear from someone that has an easier way to do the disassemble/reassemble job with success.

Jay, Idaho
 
Savage bolt truing and timing

As part of the process, I turn a shoulder on the main bolt screw for the cocking piece sleeve to align on. I tap the cocking piece through and insert a .250 X 28 X .187 set screw in the cocking piece to stabilize the cocking piece pin.I make a bushing to go between the firing pin stop and the firing pin spring moving everything rearward. I recut the cocking ramp in the bolt body. I bush the firing pin in the bolt head to both align it and prevent cratering. I am working on a completely new bolt arrangement for savages they both are in the prototype stage. One would still use the Savage style sear and trigger. The other would incorporate a Remington 700 aftermarket trigger.

2008 may bring some revolutionary aftermarket parts for the Savage actions.

Rustystud
 
Jay said:
Serious heat is required to melt the silver solder that was used by Remington.

You need an oxy/acetelyne torch and in my experience, once the two parts are separated they are unusable unless you can machine the excess solder off. Thanks, Douglas ex-pipefitter
Click to expand...
 
D R, thanks, I wasn't sure how much difference there was between dry and live but with the factory actions I'm looking at, its all bad. About the only time I dry fire is when I'm function testing or putting something away but know the stops will be hitting home sometimes and had to consider that when doing the bushings.

Jerry your probably right on, it wasn't the cratering that bugged me actually, it was the oversized hole and the firing pin hitting the primer at random locations. :D

Thanks Bill, I'll take the good question compliment but remind all even a blind pig... I think you should bush your pin and "Incorporate some semblance of Borden bumps" then tell me how to do it ;)

Rustystud, if I tap the cocking piece through and install the set screw [loctite?] to jam the cocking piece pin, do I have to touch the ramp? I ask because I have neither the tools nor skills to recut the ramp properly.

Cheers,
Rob
 
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