Headspace Question

[Phil3]

I have a question on what is appropriate resistance on bolt closure against a GO headspace gauge in my Savage Precision Target action. The ejector has removed, but the extractor was left in. The Scotch Tape used in this test measures 0.0025" thick, but if calipers are pulled tight, it goes to 0.002".I am somewhat concerned it is too tight.

1) Bolt closes on GO gauge with somewhat more resistance than without the GO gauge. It is hard to quantify how much more "somewhat" is, but if I was blindfolded, I am pretty sure I could tell from bolt feel if the gauge was in the chamber or not. I can close the bolt on the gauge with two fingers, but I have to push firmly. The Savage action is already stiff, so hard to tell.

2) I applied scotch tape to the back of the GO gauge, trimmed off all tape around the edges, inserted the gauge and tried closing the bolt. No way. The bolt stops very early and firmly.

3) I inserted new Lapua brass in the chamber. The bolt closes, with less resistance than the GO gauge, but maybe more than with no case chambered. The stiff Savage action makes it hard to tell. The brass looks fine when it comes out. No dents, or other obvious damage.

4) I applied scotch tape to the back of the Lapua case. The bolt will not close, but it felt like I could push the bolt down a bit further than with the GO gauge. Again, my hand is not calibrated.

Headspace too tight or? It is possible to damage a barrel or head space gauge if cranked down too hard on the bolt? There is no obvious damage to Go gauge. I have heard a head space gauge is softer steel than barrel steel, but I have little confidence in the source of that info.

Thanks for your thoughts.

Phil

 

[Someoldguy]

Based upon your description, your headspace setting is fine.

Curious, what prompted you to be concerned about it to begin with?

 

[#40Fan]

With all of my Savages and use of a No-Go, the bolt stops at the 2:00 position. Honestly, I use the No-Go for more of a confirmation than the Go.

I put the Go into the barrel while it is slightly pointed down and screw the action on. I listen for the click of the gauge going past the extractor. Then slowly tighten the barrel until just snug. Tight the nut which will draw the barrel away from the bolt face just a touch and check with the No-Go.

 

[nmkid]

Is this the first Savage barrel you have installed?

 

[Dusty Stevens]

Sounds like its absolutely perfect to me

 

[Phil3]

Based upon your description, your headspace setting is fine.

Curious, what prompted you to be concerned about it to begin with?

Honestly, I am not sure. I checked it when I assembled it and thought the headspace fine, and for some reason checked it again, and now, do notice it somewhat tight. What is the worst that can happen with too tight headspace? Like I said, chambered brass seems OK after extraction, so not being crushed. I did put a Sharpie line on the case neck down the shoulder to case base, chambered it, and could not find a mark on the line. But, it did feel slightly tighter on bolt closure with this new unfired Lapua case vs nothing in chamber.

- Phil

 

[Ggmac]

If you have concerns after firing brass , just keep your brass from this gun separate . Having too short of headspace will only show when your brass is fired in another Gun with longer specs for headspace .

 

[tmwinds]

Sounds like its absolutely perfect to me

I agree with Dusty, I don't see how you could get it any better.

 

[Puzzaz01]

A Go gauge is only a SAAMI spec, your head space can be slightly off either way and once you fire a round thru this chamber your brass will then be set for this chamber. Personaly I like the chamber a little loose feeling on the go gauge, that way you have no problem when properly sizing your fired brass. I bump my shoulders back 1-1/2 thou when sizing and if you have a very tight chamber...... well, that makes it a little tougher to size beacause it's already fire-formed short.

Darrin

 

[Phil3]

A Go gauge is only a SAAMI spec, your head space can be slightly off either way and once you fire a round thru this chamber your brass will then be set for this chamber. Personaly I like the chamber a little loose feeling on the go gauge, that way you have no problem when properly sizing your fired brass. I bump my shoulders back 1-1/2 thou when sizing and if you have a very tight chamber...... well, that makes it a little tougher to size beacause it's already fire-formed short.

Darrin

I am a little concerned about this. I have some fired 6mmBR brass from another rifle, so will FL size and make sure it chambers OK. Right now, that fired brass will not chamber at all. If the die cannot set the shoulder back far enough, I obviously have a problem.

 

[Puzzaz01]

I am a little concerned about this. I have some fired 6mmBR brass from another rifle, so will FL size and make sure it chambers OK. Right now, that fired brass will not chamber at all. If the die cannot set the shoulder back far enough, I obviously have a problem.

Yep, that's exactly what I was talking about.

Darrin

 

[GenePoole]

What's the big deal? It's a Savage. Just loosen the nut and move the barrel a few degrees if you're not happy with the headspace. 16 tpi gives 0.0625/360° = 0.00017in. per degree. Rotate it about 6 degrees for every thou of extra headspace you want.

 

[Phil3]

What's the big deal? It's a Savage. Just loosen the nut and move the barrel a few degrees if you're not happy with the headspace. 16 tpi gives 0.0625/360° = 0.00017in. per degree. Rotate it about 6 degrees for every thou of extra headspace you want.

What makes me happy is the appropriate amount of bolt closure resistance on the GO gauge. Since I have no experience in this, I am not sure what is too snug, just right, etc.

Your calculations are correct, for 16 tpi. The Savage has 20 tpi, making a turn of just over 7 degrees necessary for .001" change in headspace.

Phil

 

[fguffey]

1) Bolt closes on GO gauge with somewhat more resistance than without the GO gauge. It is hard to quantify how much more "somewhat" is, but if I was blindfolded, I am pretty sure I could tell from bolt feel if the gauge was in the chamber or not. I can close the bolt on the gauge with two fingers, but I have to push firmly. The Savage action is already stiff, so hard to tell.

I do not find it necessary to use a head space gage, but, when I do I do not find it necessary to use a go-gage with tape etc. because I am comfortable using a no go-gage or a field length/reject gage.

If you are using the gage to measure the length of the chamber from the shoulder to the bolt face with .002" thick tape/shim you are checking for a short chamber. In the perfect world the case is minimum length or full length sized. The case category is a large one, it includes new, factory, over the counter ammo. Problem? The reloader does not know the length of the ammo he is and or going to chamber. It has been considered closing the bolt on a solid head space gage is a very bad habit.

Length of ammo from the shoulder/datum to the case head is referred to as being 'head space by most reloaders; the reason for that mistake is caused by the failure of the reloader to read and understand. SAAMI list case length, they do not list case head space because the case does not have head space.

I have no clue who talked you into using tape on the head space gage. Head space gages are nice but head space gages come in three different sizes. Chambers do not come that way, I have 30/06 chambers that are .002" shorter than a go-gage from the shoulder to the case head, I also have 30/06 chambers that that are .0025" shorter than a no-go gage, and then there is the one that has a chamber that is .016" longer than a minimum length/full length sized case or .011" longer than a go-gage length chamber or .002" longer than a field reject length gage.

If I fired a minimum length/full length sized case in the long chamber it would have .016" clearance. I understand it sounds strange but I can measure the long chamber with a go-gage without shims and or tape. When I first measured the length of any in thousandths chambers I thought any smith and or reloader could do it. They are convinced they can not do it.

F. Guffey

 

[fguffey]

A Go gauge is only a SAAMI spec, your head space can be slightly off either way

There is nothing like being able to verify, verify the length of the gage, case and chamber. I am the fan of standards, I use standards to verify.

F. Guffey

 

[DaveTooley]

There are a few absolutes in this world.
One is some people have a headspace problem.

 

[fguffey]

Your calculations are correct, for 16 tpi. The Savage has 20 tpi, making a turn of just over 7 degrees necessary for .001" change in headspace.

And if you had the ability to verity the gage you could verify the length of the case from the shoulder to the case head. I understand that is complicated and it gets worst, if you chambered a verified case in the chamber you could screw the barrel in until it contacted the shoulder of the case; after contacting the shoulder back the barrel off and then place a feeler gage between the barrel and receiver to set your clearance, .0035" is a good number.

F. Guffey

 

[tobnpr]

As good as it gets.
When I get it to where the bolt closes with light resistance it's perfect...
I would run the new brass through your sizing die though to make sure it doesn't bump the datum any further up though if you're FL sizing.

 

[ckaberna]

LOL....

 

[fguffey]

What makes me happy is the appropriate amount of bolt closure resistance on the GO gauge. Since I have no experience in this, I am not sure what is too snug, just right, etc.

I determine the length of the chamber without crushing the go-gage. And then there are those rumors; it is said some smiths have stretched receivers by closing the bolt on gages that were too long for the chamber.

F. Guffey

appropriate amount of bolt closure resistance on the GO gauge

That would be a short chamber; how short?

F. Guffey