308 Chamber headspace is 1.621, is this considered a tight chamber?

[masterblaster1]

This is in a McGowan barrel, I have tried everything in my press, getting ready to send sizing dies out to Lee and RCBS to get them to custom trim to help me bump the shoulder back as I am not getting the bump needed to get teh cartridge in the chamber okay. The RCBS sizing die is a SB X-die so I know its not the case width. Is 1.621 a tight chamber that would require a custom die?

 

[243winxb]

SAAMI lists minimum at 1.630" for the chamber. http://www.saami.org/specifications_and_information/index.cfm?page=CC

 

[masterblaster1]

I used a match hedspace gauge to install these barrels, one is a savage 5 r barrel and the other is a McGowan, the headspace gauge measures 1.621 as well, should I reset the barrels? to a longer headspace?

 

[243winxb]

•Headspace gages are available in three different lengths, listed below, from shortest to longest:
•Go Gage: Go Gages match the minimum chamber dimensions allowable under SAAMI specifications. In order to accept SAAMI maximum ammunition, the rifle must be able to chamber the correct go gage.
•No-Go Gage: No-Go Gages are sized to the maximum recommended headspace dimensions. If a rifle will chamber the no-go gage, it may still be within specifications, or this could indicate excessive headspace. To determine if the rifle is safe to shoot, the chamber must be checked with the field gage.
•Field Gage: Field Gages correspond to the maximum safe headspace dimension. If a rifle will chamber a field gage, it should be inspected and repaired by a competent gunsmith prior to use. http://www.midwayusa.com/product/561125/forster-complete-match-headspace-gage-set-308-winchester You need to ask a gunsmith, as i dont really know. I have only used a field gauge.

 

[masterblaster1]

I live in south Fla, no smiths around that I trust. I am looking at my go gauge it is giving me a measurement of 1.621, I wonder if I got a lemon.I will call PTG.

 

[stool]

how and with what are you measuring your headspace gage ?

 

[masterblaster1]

I mean my ptg go gauge to be more precise, sorry I omitted in OP.

 

[Concha]

This really is an easy fix. It is a savage after all.

 

[Erik Cortina]

Sounds like it is a Savage pre-fit barrel.

Have someone that knows what they are doing install the barrel for you. Do not let the same guy that installed it previously touch it again.

 

[stool]

i'm still lost.....you have a 1.621 ptg headspace gauge ??

how have you come up with the 1.621 number ??

 

[Concha]

Thanks Erik. I went back and read some of the OP's other threads and figured that out. I also edited my first post.

I was thinking what Stool posted. Also verify the calibaration of measuring tools and implements.

 

[Erik Cortina]

how and with what are you measuring your headspace gage ?

This is an important question.

 

[masterblaster1]

Stool, the go gauge is measuring 1.621 using the Hornady headspace tool.

 

[Erik Cortina]

Stool, the go gauge is measuring 1.621 using the Hornady headspace tool.

I don't think the Hornady tool is accurate enough for this kind of measuring.
Get a reamer print and it will tell you the measurement from base to datum line on shoulder. It will also tell you the diameter of the shoulder at that point. The tool needs to be that diameter and not chamfered to get a close measurement.

 

[Concha]

did you reset your calipers to zero with the gauge installed.?digital or dial) Did you account for any wear at the face to bore junction?

 

[masterblaster1]

Yeah, they are zeroed, digital. Eric, what you are saying is the chamfer on the I.D of the 0.400 insert is giving me a false (shorter) reading because of the relief?

 

[Concha]

Yes. If the bolt closes on the gauge you need to back off a few degrees.

 

[stool]

ok lets try some shade tree shop work.
can you strip your bolt ?
does the bolt close on the ptg head space gauge.

one step at a time.....

 

[masterblaster1]

Yes I installed the barrel, when I did I stripped bolt and usd this headspace gauge, now my dies barely get the brass sized down enough to fit tightly in the chamber. I was about to send my dies in to get them cut by RCBs and Lee but started thinking that this problem started when I switched barrels so I measured the headspace gauge and looked tat min sammi spec. Now I am thinking that the gauge is out of spec. This happened with two different barrels on two different 308's.

The bolt closes on both with headspace chambered, but wont close with a piece of scotch tape on the back, I gauged the scotch tape at 2 thou after I put it on the gauge web.

 

[stool]

ohh welllllllllllll
will it close on a commercial 308 win round ?

measure that case
now add tape to the base till the stripped bolt will not close...

there is no way a ptg go gauge is out by that much...


something you are doing is not correct