Barrel breech to bolt spacing.

F

frwillia

Guest
I was sitting here doing some arithmetic to determine how long the barrel tenon should be on my Savage LRPV (right bolt left port target action) .22-250 Rem. if I was going to chamber a barrel that wouldn't use the barrel nut.

I measured 1.061" from the forward face of the recoil lug (the far side from the bolt) to the bolt face. The bolt face is 0.116" deep. If I subtract 0.116" plus the desired bolt to barrel breech gap, that would be the tenon length. Right?

That brings me to the bolt to barrel breech gap. The way the rifle was set up from the factory gives me 0.015" of bolt to barrel breech gap determined as follows: My bolt recess is 0.116". The Go-Gage sticks out of the barrel .128". That means that at zero headspace clearance I have .128 - .115 = .013" of gap between the bolt and the breech end of the barrel, which means there is 0.013" of exposed brass there. In reality I have something like 0.015" because there is about 0.002" of clearance between the bolt face and the headspace gage with the bolt closed.

Which brings me to my question: Should I be going for a smaller gap between the bolt face and the breech end of the barrel? If so, what gap is recommended?

One more question: Do folks ever machine a bit of a recess in the barrel breech to eliminate the exposed brass between the barrel and the bolt in a Savage?

Thanks
Fitch
 
Stick a case in the chamber. You will see that only the extractor groove is sticking out of the chamber. Now a Remington on the other hand has quite a lot of case sticking out of the chamber.
 
claerance ( center fire rifles )

i always use .008 ot .010 where i can would work tighter, but tried as little as .002 it in past and found that i got in trouble with hot day's debre build up :(

just now iam shooting a sako and the bolt nose claerance is .018 or the extractor will not work, my savage pta in 22br as bolt nose claerace of .008 with the barrel fitted with out nut !! and workd grate
 
I would not make it less than 5 thou clearance. I would probably go with 10 thou clearance. Make sure your bolt is stripped and "back" against the lug recesses when measuring. Most case heads can hang out 160 thou with no problem at all but why do more than you need.
 
Dennis Sorensen said:
I would not make it less than 5 thou clearance. I would probably go with 10 thou clearance. Make sure your bolt is stripped and "back" against the lug recesses when measuring. Most case heads can hang out 160 thou with no problem at all but why do more than you need.
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Thinking about it a bit, 0.010" seems like a good specification. It's big enough to avoid problems with the sort of stuff one might find in a single shot target/varmint rifle.

I'll go with that unless something compelling turns up leading to a larger gap.

Fitch
 
The headspace gauge should extend .125" minimum and .130" maximum out of the chamber. As mentioned, the gap between the barrel and bolt head should be .010". Fits perfect with the .116" recess. You may as well true the lugs to the face and remove the rad so you can reposition the washer, the later helps grease stay put. Be sure not to remove too much, a few thou off the face will do. I touch up the front of the head as well but very little because of the extractor. I go for a .118" recess and a .008" gap but accept any combo within reason. So long as it passes the official headspace checks, I like to use a resized case because my sizing die has the final word in headspace.

No barrel recess, won't work for that bolt head.
 
Savage Headspace

Rob what die are you using to determine the final word on your headspace. Thanks Tony
 
PEI Rob said:
You may as well true the lugs to the face and remove the rad so you can reposition the washer, the later helps grease stay put.
Click to expand...

I followed the rest of the post just fine, but I want to make sure I understand what you mean by "reposition the washer". This is a perfect "picture save a 1000 words" opportunity. Is this what you are talking about?

Washermove-1ARS.jpg


If that is what you are talking about, is there a down side to doing that?

Thanks
Fitch
 
my sizing die has the final word in headspace
Click to expand...
A full length sizing die determines the final size of the case. If the die is on the short side of the spec limits then the cases will also be one the short side and therefore have more "gap" than a die made long. Partial full length sizing is very common but does not always work or may not be desired. Think of using a headspace gauge set and all is well. You could be at the long limit but within spec. Now use a sizing die that is made short. You will have max allowable case stretch, which is way more than you might think, IIRC its around .020" for a .308 win. Why not match the headspace measurement to your sized case and have no stretch?

frwillia, yep. You will note the radius on the head won't allow you to move the washer there. Removing the radius while truing the head permits the washer to be placed there which helps grease stay on the lugs. No downside, there is not much force at that junction so removing the rad won't cause problems.
 
PEI Rob said:
Why not match the headspace measurement to your sized case and have no stretch?
Click to expand...

I wish I'd thought of that. Makes sense. I may do exactly that. I full length size all my new brass before I shoot it anyway. The LRPV is a varmint/target rifle that won't see a factory round while I own it so there's no issue there. I could set it to headspace with about .002 on resized brass.

I might need to adjust my powder charge downward a tenth or two to make up for decreased case volume.

frwillia, yep. You will note the radius on the head won't allow you to move the washer there. Removing the radius while truing the head permits the washer to be placed there which helps grease stay on the lugs.
Click to expand...

I've not disassembled a Savage Bolt before. I found instructions to disassemble the bolt on the WEB. I may do that today. It would be better to have the firing pin and extractor removed when I'm using it to check headspace anyway, right?

No downside, there is not much force at that junction so removing the rad won't cause problems.
Click to expand...

I'm inclined to agree with you but want to ask a question first related to rifle motion during the first few milliseconds after the powder burn takes place and before the bullet leaves the barrel.

Where the washer is now, the other "thing" (I don't know what the proper name is) is pressed against the back of the bolt head. That is, it's up against the back of the locking lugs. I realize it is actually turned 90 degrees and is only against it in the center when the rifle is fired. As it is now, the "thing" is against the locking lugs so it moves to the rear with the locking lugs and probably doesn't do any "bouncing" till after the bullet has left the barrel. If I put the spring in between, the locking lugs get a head start and the "thing" will slam into them after spring compression as they head to the rear during recoil. They don't move far, but they do move. The spring will probably soften the blow a bit.

The heavier the rifle, the less of a problem this might be.

I'll probably try it anyway, though not in concert with other changes because I like to see if I can isolate the effect of changes. I'll recut the crown, try the rifle, then if I still think it's a good idea, I'll do as you suggest with the bolt.

That said, out of due dilligence if for no other reason, I have to ask if you have done any before and after testing with just that one change?

Thanks
Fitch
 
Getting a bit off topic now, but truing the lugs on this Savage bolt has me confused. The bolt head pivots on a cross pin and is most definitely not rigid with the bolt body. The lugs make contact on both sides because they can't help it so unless the bolt face isn't square with the bore centerline, it doesn't matter.

I haven't taken it apart yet.

I think Savage bolts are a completely different animal than any of those in the book I have. For sure aren't like remington bolts.

Fitch
 
crb said:
Stick a case in the chamber. You will see that only the extractor groove is sticking out of the chamber. Now a Remington on the other hand has quite a lot of case sticking out of the chamber.
Click to expand...

crb

You make it sound like the Rem design is inferior. The nominal bolt nose recess in a remington barrel is only .150" and on a custom job it can be reduced to .130" or so. The solid web of most modern hi-intensity cases in .200", or more. That's quite a substantial safety margin. Plus the Rem has a solid ring of steel over the bolt nose, something that most other actions do not have.

JMHO

Ray
 
The solid web of most modern hi-intensity cases in .200", or more. That's quite a substantial safety margin. Plus the Rem has a solid ring of steel over the bolt nose, something that most other actions do not have.

You are right Ray..

The 700 series (unaltered) is the strongest, safest mass produced action ever made.


.
 
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Ray,
If I thought Remmys were inferior I wouldn't have sold all my Savages and replaced them with Remmys ;).

I did recut the bolt nose on a PTG bolt that has a Sako extractor. No need for .150 when the Sako ext will accomodate .120 or so. Also I wanted to rebate some 6PPC cases so I could use a PPC bbl with this 223 bolt face. I don't consider that possible with the .150 depth.
 
Another point to remember, through the same die, hard brass won't size down as much as fresh brass. If you set up for zero gap, you'll know when to anneal soon enough.

The bolt face is dished due to the tumbling process at the factory, about .003". After cutting the face the lugs are trued to the new face. Not likely needed but hey, its fun.

I haven't done a test and usually change many things if any at all. I've never diagnosed or heard of front baffle movement causing any trouble but cannot say anything more than my limited experience. Really don't think it does but I'd bet it would take a tunnel to confirm.
 
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