Excessive Headspace and Sizing Cases

[Fcb]

It looks like my M1917 has just a bit of excessive headspace as evidenced by protruding primers and excessive case stretching rings using full power loads. If I use reduced loads, this seems to not be an issue. My question is there a way to adjust your die to resize your case to accommodate for this longer chamber? Or after you have fire formed the cases, then would neck sizing only be best because the case is now a fit for the chamber? It seems the headspace is not TOO excessive that it needs gunsmith work but want to hear what you experienced folks and maybe some gunsmiths have to say. Thanks in advance.

[racepres]

The headspace is only excessive if You size the cases to make it so... All of my bottleneck cases get treated the same as my Wildcats..

[Hannibal]

Back your sizing die off about 4 turns and size a case. Check to see if the neck is fully sized and if the base to shoulder dimension has changed. Adjust the die so you get a completely sized neck but no shoulder set back. You will need a comparator such as the Hornady model to do this correctly.

Also be careful if you are stretching your case much or you will have case head separations eventually. Particularly if you've already fully sized your cases and stretched them a couple of times.

[Der Gebirgsjager]

The best solution is probably to just neck size the fired cases. They have expanded from the first firing to fill your chamber and have stretched to compensate for the excess head space. If you just neck size and reload them they should work fine in your rifle. I know you have a 1917, but this problem is quite common in Lee Enfield rifles as well, and that is the solution. Unfortunately, the cases have been somewhat weakened from the stretching, and will probably separate at the stretch mark after fewer reloadings than you would expect to get. This is not dangerous, as it usually appears as a crack observed after firing and you can discard them before the next shooting. Even if they separate in the chamber there is little danger. You may find the case head comes out with the extractor, and you can usually remove the body remaining in the chamber with a .45 cal. cleaning brush on a rod inserted into the case. It will come out with the brush when removed. As for correcting the headspace, the normal way would be to remove and set the barrel back to original specs. A less conventional way would be to try some other bolts and perhaps one would solve the problem. Your bolt's lugs may be worn a bit.

DG

[hades]

I would do what Hannibal suggests. Reduce your shoulder set back to 2 thousandths. A head space comparator gauge is the best and easiest way to measure but a spent casing works too if you find one thats nice and square or trim it so the case mouth is perfectly square. 40 SW/10mm would work perfect as a cheap make shift comparator insert.

[Fcb]

Thanks everyone - great advice!

[Rich/WIS]

30/06 brass is plentiful so would suggest you discard any that make you suspicious of possible head separation. Starting with new or once fired brass from a rifle with proper headspace neck size only and seat your cast bullets to engage the rifling when the bolt is closed. A mild load is better as it will not seize to the chamber walls like a full power load and let the case move back against the bolt face. When reloading these cases only neck size and try the cases in the chamber. If they chamber fine load them, if they are hard to close the bolt on size only enough to allow easy chambering. The cases are now fireformed to match your chambers headspace.

[Hannibal]

30/06 brass is plentiful so would suggest you discard any that make you suspicious of possible head separation. Starting with new or once fired brass from a rifle with proper headspace neck size only and seat your cast bullets to engage the rifling when the bolt is closed. A mild load is better as it will not seize to the chamber walls like a full power load and let the case move back against the bolt face. When reloading these cases only neck size and try the cases in the chamber. If they chamber fine load them, if they are hard to close the bolt on size only enough to allow easy chambering. The cases are now fireformed to match your chambers headspace.

I would have to disagree with you about the mild loads. I have found that cases will often not fireform to the chamber fully without a full power load and even then it sometimes takes 2 or 3 firings. This isn't a big issue unless you are measuring shoulder set back. Once you go down that road if your cases are already a a few thousands from being fully formed and then you set them back .002" now you just compounded the very problem you are trying to fix.

[stubshaft]

I would have to disagree with you about the mild loads. I have found that cases will often not fireform to the chamber fully without a full power load and even then it sometimes takes 2 or 3 firings. This isn't a big issue unless you are measuring shoulder set back. Once you go down that road if your cases are already a a few thousands from being fully formed and then you set them back .002" now you just compounded the very problem you are trying to fix.

I have found that for the most part they will form to the chamber with milder loads if you anneal the brass first.

[atr]

yes, just back off the full length die to achieve neck sizing only. It doesn't take much backing-off, I usually back off 1/4 of a turn.

[M-Tecs]

The basic instructions that the die makers recommend are just that basic and a starting point that should work in all SAAMI spec chambers. That doesn't mean they are the optimal method of adjusting your dies. For the most part I have given up on neck sizing only. I do control the shoulder bump to .001" to .002" for bolt guns and .002" for 003" semi-autos, pumps and lever guns.

When you have a chamber with excessive headspace the best methods are to neck up and form a false shoulder or jam the bullet into the lands if you can. That will eliminate the excessive case stretch from the first fireforming.

Once you have a case that is fully formed to the long chamber you need to set your die for the amount of shoulder bump you want. The Hornady Lock-N-Load® Headspace Comparator or the RCBS Precision Case Mic work well for this.

You set the should bump by slowing adjusting the die until you get the bump you want.

No need to have the barrel setback using these methods. You basically are loading for a very mild form of wildcat is the chamber is outside SAAMI specs.

Good overview of the process here

http://www.floridareloading.com/inde...tleneck-cases/

[Fcb]

The basic instructions that the die makers recommend are just that basic and a starting point that should work in all SAAMI spec chambers. That doesn't mean they are the optimal method of adjusting your dies. For the most part I have given up on neck sizing only. I do control the shoulder bump to .001" to .002" for bolt guns and .002" for 003" semi-autos, pumps and lever guns.

When you have a chamber with excessive headspace the best methods are to neck up and form a false shoulder or jam the bullet into the lands if you can. That will eliminate the excessive case stretch from the first fireforming.

Once you have a case that is fully formed to the long chamber you need to set your die for the amount of shoulder bump you want. The Hornady Lock-N-Load® Headspace Comparator or the RCBS Precision Case Mic work well for this.

You set the should bump by slowing adjusting the die until you get the bump you want.

No need to have the barrel setback using these methods. You basically are loading for a very mild form of wildcat is the chamber is outside SAAMI specs.

Good overview of the process here

http://www.floridareloading.com/inde...tleneck-cases/

Thanks. This is really helpful and I understand what you are describing. After the cases are fire-formed I could just neck size but you said you have given up on that. So you believe in FL resizing with a die adjusted to what is required for that chamber. Does this mean you believe neck sizing the fire-formed cases is not sufficient for a chamber with excessive headspace?

[M-Tecs]

Thanks. This is really helpful and I understand what you are describing. After the cases are fire-formed I could just neck size but you said you have given up on that. So you believe in FL resizing with a die adjusted to what is required for that chamber. Does this mean you believe neck sizing the fire-formed cases is not sufficient for a chamber with excessive headspace?

With neck sizing only at some point you will have to bump the shoulder or you will get hard bolt closing. With proper shoulder bump that never is an issue. The primer pocket will fail first or the necks will split long before head separation becomes an issue. Accuracy with a proper shoulder bump will be equal for your application.

For what you are doing neck sizing only has no advantages and the one disadvantage verse a proper FL sizing and shoulder bump.

[Hannibal]

With neck sizing only at some point you will have to bump the shoulder or you will get hard bolt closing. With proper shoulder bump that never is an issue. The primer pocket will fail first or the necks will split long before head separation becomes an issue. Accuracy with a proper shoulder bump will be equal for your application.

For what you are doing neck sizing only has no advantages and the one disadvantage verse a proper FL sizing and shoulder bump.

I've had more extraction problems than bolt close problems but yes, if one is difficult the other is sure to be about to become a problem too.

[Fcb]

With neck sizing only at some point you will have to bump the shoulder or you will get hard bolt closing. With proper shoulder bump that never is an issue. The primer pocket will fail first or the necks will split long before head separation becomes an issue. Accuracy with a proper shoulder bump will be equal for your application.

For what you are doing neck sizing only has no advantages and the one disadvantage verse a proper FL sizing and shoulder bump.

Thanks for the more detailed explanation - I get it.

[lar45]

my 9.3x57 has very excessive head space. I expand the necks on the cases, then run them into my sizing die that is not screwed in all the way. Check the case to see if it will chamber, turn the sizing die in a little, size the case a little bit more and recheck until the bolt will just close. I lock the nut on the sizing die in this position and do all the rest of the cases.
Next, you will fireform and blow the shoulder out to it's new longer position. After this, just neck size and your cases will be fine. Just mark the ammo box for which rifle it's to be used in.

As was mentioned above, you can also seat a cast bullet longer and achieve the same result. Seat a cast bullet in your loaded case so that it jams into the rifling, this will hold the base of the case back against the bolt face. When you fire the round the shoulder will be blown forward to fill the chamber. After this adjust your dies so you neck size only and you should be fine.

[kentfielddude]

I have a m1917 that eats a field gauge. I'm kind of scared to shoot it to form the brass. If I seat a cast bullet so it jams into the rifling is it safe or is there still a concern with saftey?

[lar45]

Should be totally fine. The cast bullet will hold the case back against the bolt face while the front of the case expands to form to your chamber.

[kentfielddude]

I have another m1917. I haven't tested it with the field gauge yet. When I got the rifle the bolt was stuck closed. After a considerable amount of force and hammering I finnally got the bolt open. There was an empty brass case stuck in the chamber. Had to drill and tap the base of the brass to thread in a rod that I could use to pull out the brass (didn't have a metal rod long enough to push it out). Brass headstamp was R-P 30-06 SPRG Picture of the removed brass:

I then shot one round through this m1917 and the bolt also was also stuck but not nearly as bad as when I got the rifle. I could open it just using my hands. The brass was quite fire formed to the chamber and you could see indentations in the brass of where there was pitting in the chamber. Scared to shoot that one again.

[racepres]

I have another m1917. I haven't tested it with the field gauge yet. When I got the rifle the bolt was stuck closed. After a considerable amount of force and hammering I finnally got the bolt open. There was an empty brass case stuck in the chamber. Had to drill and tap the base of the brass to thread in a rod that I could use to pull out the brass (didn't have a metal rod long enough to push it out). Brass headstamp was R-P 30-06 SPRG Picture of the removed brass:
I then shot one round through this m1917 and the bolt also was also stuck but not nearly as bad as when I got the rifle. I could open it just using my hands. The brass was quite fire formed to the chamber and you could see indentations in the brass of where there was pitting in the chamber. Scared to shoot that one again.

Long as the Gasses are Not coming at yer Face!!!
Seriously.. steel wool, and try to clean up the chamber... if it was a real Mauser, The barrel comes off easy enough to set the barrel back 1 thread.(maybe worthwhile). But, The 1917 (and the '03 as I have heard) do Not give up the Barrel easily!!!
Certainly If you can clean that chamber up... you Need (ie pretty much have to) keep the Brass separate for that rifle..