Headspace gauge variations got me confused

[opos]

I've done some searches concerning the headspace data on the 1917 and seem to always come up with threads that veer off into the 303 arena so I'll hope to not aggravate folks with my questions...I'm familiar with the 1917 and the probability that the modern SAAMI headspace gauges are "commercial" and not as large as the military gauges.

Here is my dilemma. I was recently given a Winchester model of 1917 in very nice condition. I have a set of Forster gauges for 30-06 and set out to check the headspace...I fully stripped the bolt/extractor..."hyper cleaned" the chamber, bolt lugs, etc and was not surprised when it ate the NOGO gauge...I then took the field gauge and very gently checked it...the bolt would not close (moved to about 2/3 closed and stopped...didn't "push it"...

Now for my question...I was looking at Hatcher's note book and several other postings I've found on the 1917 headspace and they seem to make reference to the Field headspace length of 1.9xxx inches...my Forster NO go is 2.0547 and the Field is 2.0577. Neither seems to be in that "under 2 inch" range...is there something I'm missing? Is Forester using a different datum point on the shoulder or am I losing it?

I would assume (bad word) that with the rifle not closing on the Field I'm probably fine to go...I do handload and I do neck size after the first firing and I load medium loads in anything I load..nothing hot. I got a box of Federal American Eagle fired brass (once fired from this rifle) and it shows no signs of any issues at all..

I'm probably being overly fussy but the different lengths I see quoted for the gauges vs what my gauges show is confusing to me...old and easily confused.

Sure appreciate any comments on the 30-06 gauges..

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[RC20]

I don't know about the gauge specs and measurements

I don know form going over maybe 10 of the 1917s, they almost close on field gauge, seems to be the reality and good enough regardless and no issues with shooting reloads

[Cosine26]

http://i116.photobucket.com/albums/o...eadspaceR2.jpg
The Gi headspace gauge reference point is different from that used by commercial (SAMMI?) headspace gauges. The above is extracted from Hatcher's Notebook and shows how the reference point is determined for the GI gauge.
The three GI gauges are GO 1.940, No Go, 1946, and Field 1.946. The notes at the bottom of the illustration show normal ordnance acceptance criteria.
The commercial gauges are usually marked 2.XXX (I do not remember the exact measurements) and I do not know the reference point.
Measuring the headspace of a M197 type action is not as straight forward as with other actions.

[jmoore]

As far as M1917s seeming to have largish headspace, don't forget that, unlike most Mauser actions, the locking surfaces are inclined. Gives you about 100:1 leverage on bolt turn down! It also means that only the last fraction of bolt turndown has any meaning for gaging. Your basic Mauser will either allow the bolt to close on the gage or not at the commencement of turndown. L-Es gage the same way as M1917s except their locking surfaces are rather more inclined.


Seems that your M1917 ought to be fine in the chamber length department, opos.

[Chuckindenver]

well,
put the books down,
heres how you check headspace...
as you did.
remove the fire control {striker} can have an extractor.
with the tool dry..slowly insert the tool, close the bolt slowly, even if it closes...if you can feel the bolt press against the gauge, it passes.. ideal is not to close on the guage.
Forester gauges are out of spec for most mil surp bolt guns,
No Go.. and Field reject are really the only 2 you should worry about.. if it doesnt close on the field.. your good to go..
dont over think it, and just enjoy the rifle.

[opos]

Thanks...I figured I was fine but the differrence in numbers just threw me for a loop.

See you are from Denver..I was born there and raised there, and in Fort Collins and Granby...great state...not much for the snow anymore at my advanced age.

Got a question about 1917 bolts that you or other 1917 folks might help with. I have a neighbor that has a "sporterized" 1917 that has a cock on opening modification and diffeent safety than stock...he asked me if I could help him tear the bolt down...I've always used the "nickel trick" on a 1917 but that won't work on a 1917 that cocks on opening as far as I can see..I don't want to try and "help" and then end up going to the smith with a box of parts...any comments appreciated...I've tried several sources and find nothing..thanks
opos

[Chuckindenver]

use the edge of a table to catch the sear. pull it down, put your nickle in just like the others.