M1917 Headspace Question

[fguffey]

chuckindenver, If I was selling Eddystones that is the way I would present them, before the Internet, the Eddystone had a reputation of being anyone's guess when it came to quality.

Bolt set back: if the bolt sets back where does it go? An expert on the M1917 will suggest checking the bolt handle contact, as you should know the M1917 does not have a 'third lug', the bolt handle is the third lug. If the bolt sets back the bolt handle supports the bolt or it shares in the support, and as you should know there is not a lot of room in front of or behind the bolt handles when fitted to the receiver.

Then there is the 'bucket of bolts mentality' when purchasing bolts, it is suggested, when purchasing bolts, purchase two or three etc., seems one day a reloader/smith would discover the effect the bolt has on off setting the length of the chamber can be measured.

Again, an old member of this forum was having trouble determining the length of the chamber in thousandths. I went over to load a Mill I purchases and while there I checked his chamber length with a feeler gage and the ammo he was going to fire. I verified the length of the chamber with one of his head space gages and a feeler gage. He had no less than 80 bolts, I had no less than 30 bolts for the rifle he was working on, I offered to check all of his bolts for their ability to off set the length of his chamber with out installing the bolt.

I knew none of my bolts would help him, in time he got help from a resource/collector.

F. Guffey

[chuckindenver]

bolt set back..
if you remove the barrel,
and look into the face of the action, you will see the locking lug ways..were the back of the locking lugs ride against the receiver.
the 1917 is 3.5% nickel steel, as is the bolt, both are only surface hardened.
with amount of camming pressure the 17 has, after time, the bolt wears through the way or weigh...on the receiver, setting the bolt back..
you can buy time with a new bolt, or use a USMC or K marked bolt as they were made of 8620 steel and run smoother, and tend not to gual the steel.
however...this usually death for the receiver..

[fguffey]

"You assume way too much, sir"

I appreciate this approach more than I appreciated the"

"My goodness. Someone certainly is full of himself!"

In the beginning there was a drawing illustrating a case with a line through the shoulder area of a case, with an arrow pointing to the line and the caption, "Datum line", then the total amount of information in the description claimed "And that is how they do it".

The datum was not a line, it was a round hole/circle, with all the space used when posting the illustration there was never mention of the diameter of the datum or the distance from the datum to the head of the case, even today the case has a length measured from the datum to the head of the case but the case does not have head space, the case has a length that off sets the length of the chamber.

If I assume too much? I can not disagree, I assume collectors/reloaders/smiths are capable of understanding the concept.

Perception in my assuming, there are members that do not know and or understand and they do not want anyone else to understand.

F. Guffey

[chuckindenver]

you can see all the measuring and high tech work that went into making a 1917 barrel....this short film puts a nother spin on the over all.
http://www.criticalpast.com/video/65...ough-periscope

[fguffey]

Chuckindenver, not easy to respond, you changed/edited your post, I ask about the set back bolt, "Where does it go? Back? When the bolt moves back what does it hit?, What stops the bolt from moving back?

F. Guffey

[chuckindenver]

bolt set back..
if you remove the barrel,
and look into the face of the action, you will see the locking lug ways..were the back of the locking lugs ride against the receiver.
the 1917 is 3.5% nickel steel, as is the bolt, both are only surface hardened.
with amount of camming pressure the 17 has, after time, the bolt wears through the way or weigh...on the receiver, setting the bolt back..
you can buy time with a new bolt, or use a USMC or K marked bolt as they were made of 8620 steel and run smoother, and tend not to gual the steel.
however...this usually death for the receiver..

you missed it...sometimes you have to log out and log back in..

[chuckindenver]

a picture for your veiwing pleasure..
as you can see. the ways are worn through the hardening...it was really time to retire this ol girl..

[chuckindenver]

bolt set back is the most common issue with 1917,s and P14s..and if this bad...a killer.. just a matter of time before a load of hot gas is blown in the shooters face.
please keep in mind..
most of the reader on this and other sites..are average shooter hobbiest collectors, just a regular Joe with a attraction to old rifles...
sometimes a basic simple answer is really all thats needed to help...
i too get to long and drawn out and have to catch myself...i remember to make it easy to read and understand.

[oldtirediron]

1917 headspace!

This subject has been bouncing around since at least 1946-- You can read about it in Hatcher's Notebook and If I remember correctly they reamed a 1917 out to some monsterous oversized condition and the rifle still shot and sometimes the accuracy even increased! if it were my rifle I would disassemble the bolt clean the chamber, receiver, bolt bearing areas and the bolt-- Then I would check the headspace and see what it reads!! Next step I would try and get a new bolt and check the headspace with that one-- Next step?? all depends!! Most of these rifles are fixed rapidily with a new bolt---I think a lot of these rifles are and are being messed with by people Matching up the parts!! The military armorer didn't care who made the part-- just as long as it worked!

[fguffey]

This subject has been bouncing around since at least 1946-- You can read about it in Hatcher's Notebook and If I remember correctly they reamed a 1917 out to some monsterous oversized condition and the rifle still shot and sometimes the accuracy even increased! if it were my rifle I would disassemble the bolt clean the chamber, receiver, bolt bearing areas and the bolt-- Then I would check the headspace and see what it reads!! Next step I would try and get a new bolt and check the headspace with that one-- Next step?? all depends!! Most of these rifles are fixed rapidily with a new bolt---I think a lot of these rifles are and are being messed with by people Matching up the parts!! The military armorer didn't care who made the part-- just as long as it worked!

There was situation One, situation Two. The assumption, head space causes case head separation, problem: No one doing the test knew what they were looking for. The shoulder was moved forward .080”, the difference in length between the chamber length and case length was .085”, when fired the shoulder of the case did not move, it was erased when a new shoulder was formed. How would they have know? Hatcher and his crew could have scribed the shoulder of the case before firing and then again after firing.

Scribing: If the case had been scribed at the case body/shoulder juncture they would have knew the case did not stretch between the case head and case body. They would have know the case did not stretch ‘period’, had they scribed the case body/shoulder juncture they would have know part of the shoulder became part of the case body and part of the neck became part of the shoulder. The case head spaced on the extractor. There are other receivers that do not have the Mauser type extractor. I have fired 8mm57 ammo in an 8mm06 chamber, that is .127” difference in length between the chamber and ammo, I ejected 8mm06 cases with very short necks, meaning most of the shoulder became part of the case body and most of the neck became part of the shoulder. I could have used a different receiver without the Mauser claw, meaning another extractor of a different design may not hold the case.

Changing bolts, I have no less than 40 Springfield bolts, I do not find it necessary to switch/change bolts to determine the effect the bolt will have on the length of the chamber, the effect the bolt has on changing head space/length of the chamber can be measured and compared with the bolt that has been removed. I have 12 M1917 bolts, with 2 exceptions 10 of the bolts will not change the length of the chamber .001”, the two exceptions are bolts that have been opened for magnum belted cases.

The M1917 does not have a third lug like the Springfield or Mauser, the bolt handle is the safety lug, when checking for bolt set back I check the clearance behind the the bolt handle. Checking the clearance is possible, if the clearance is measured bolt set back can be tracked.

F. Guffey