Headspace Issue?

[geraldgee]

I was recently asked a question about headspace that I can't answer and would like to hear your opinions.

A new build .260 hunting rifle based on blueprinted Rem700. The factory fired ammo appears to have stretch marks on them.

EDIT -The cases pictured in the thread have not been resized. This is how they appear directly from the chamber

Are these cases showing headspace issues? Can anyone explain the markings on these cases?

Thank you in advance for your input.

Gerald

 

[mao0720]

That looks like it's just where the brass is contacting the inside of the die while sizing. Take a paper clip and straighten it except for a small "L" at the end. Stick it in your case and run it up and down the case wall to see if it hangs up on a thin spot in the wall. This will tell you if you have excessive case stretching. Out of curiosity, how much did you have to trim off the brass after resizing?

 

[geraldgee]

The brass you're looking at has NOT been resized. You are looking at the cases as they came out of the chamber after firing.

 

[ebb]

What moa 0720 said. The web is solid metal all the way through, except for the flash hole. No way you are going to size it so the die is made so it doesn't.

 

[SheepDog]

So, the cases came out of the chamber they were fired in and they have not been sized yet.
i don't see any bright ring to show stretch just the finish change on the brass.
Was extraction at all hard? I wouldn't expect so. The pressure just pushed the brass into the chamber wall and changed the finish. You can check the inside of the case for a ring but if it doesn't show on the outside it's not likely you will find one on the inside.
I think the brass is fine. I see no indications of any problems.

 

[long40shot]

Any blown primers? Any ejector marks?

 

[geraldgee]

No extraction difficulties whasoever - no bolt lift problems. I have a picture that seems to indicate that the primer backed out some. Please bear in mind this is factory ammo - not hot-rodded hand loads.

 

[geraldgee]

 

[geraldgee]

Slight mark between 260 and REM

 

[Shawnba67]

i have a couple that do that I always assumed it was due to the chamber finish

 

[SheepDog]

I see a case that has a primer with a rounded radius and a slight mark from an ejector. It could be near a maximum load or it might be a slight lack of clearance of the ejector. Either way I see nothing that shows a problem at this point. None of the visible marks will show after the cases are sized and polished. Resized them just enough that the shoulder/neck junction is defined and load them up.

 

[4xforfun]

View attachment 1011979 No extraction difficulties whasoever - no bolt lift problems. I have a picture that seems to indicate that the primer backed out some. Please bear in mind this is factory ammo - not hot-rodded hand loads.

WOW...that looks hot, factory or not. Take a new round and put 1 piece of scotch tape on the back of the case where it makes contact with the bolt face and trim it to match the back of the case. If you have a bolt tool, take the bolt apart and chamber the round with the tape on it. Does the bolt close. NO...headspace is fine. Yes...add another piece of tape, trim and chamber. Does the bolt close? No...probably ok, yes...add ANOTHER piece of tape and so on ...till it won't chamber. Let us know. General rule is 1 piece of tape = .002 headspace. This is a GUIDELINE...not a hard rule. DO NOT FIRE THE ROUNDS WITH THE TAPE IN PLACE....THIS IS JUST FOR MEASURING!!!

Let us know. You don't have to take your bolt apart, but it helps to feel how much, if any effort it takes to close the bolt. Also, if it takes more than one piece of tape you can easily measure the thickness of the tape as it peels off of the back of the case in one piece.

Good luck,
Tod

 

[Iowa Fox]

I've seen that on quite a bit of range brass that I pick up to examine. I know the guys were shooting factory ammo in factory guns. I came to the conclusion for my mind that some factory chambers are rough and that web line where the dull finish starts is where the case bites the chamber when fired, that bottom part, shinny, doesn't bite the walls. The ones I look at do not have any case stretch to speak of.

 

[Northridge]

It could very well be a chamber texture imprint on the fired case. Does not always indicate high pressure or a in accuracy problem. I've experimented with chamber texture surface finish in the past heavy texture to fine texture or finish. Depending on case geometry and how are you run that cartridge different textures will perform better and some worse. I don't believe you have a headspace issue

Shawn Williams

 

[johnfred1965]

i have a couple that do that I always assumed it was due to the chamber finish

What he said. Your gunsmith didn't polish up the chamber when he cut it. I know of many who will take a piece or crocous cloth or fine steel wool and a bit of oil and clean up the chamber after cutting. It isn't really a problem if you don't mind it looking a little different after firing. If you can't stand it anymore, take some isso paste and a bore mop on a short piece of cleaning rod, chuck it in a drill and polish it yourself.

 

[geraldgee]

WOW...that looks hot, factory or not. Take a new round and put 1 piece of scotch tape on the back of the case where it makes contact with the bolt face and trim it to match the back of the case. If you have a bolt tool, take the bolt apart and chamber the round with the tape on it. Does the bolt close. NO...headspace is fine. Yes...add another piece of tape, trim and chamber. Does the bolt close? No...probably ok, yes...add ANOTHER piece of tape and so on ...till it won't chamber. Let us know. General rule is 1 piece of tape = .002 headspace. This is a GUIDELINE...not a hard rule. DO NOT FIRE THE ROUNDS WITH THE TAPE IN PLACE....THIS IS JUST FOR MEASURING!!!

Let us know. You don't have to take your bolt apart, but it helps to feel how much, if any effort it takes to close the bolt. Also, if it takes more than one piece of tape you can easily measure the thickness of the tape as it peels off of the back of the case in one piece.

Good luck,
Tod

I'll certainly pass this suggestion on and get back to y'all.

I appreciate all the input - thank you.

 

[geraldgee]

I spoke with the gun owner who explained that he can close the bolt on a PTG nogo gauge but if he adds a piece of tape (.002 as above) the bolt no longer closes. Is this dangerous? Can the brass be used to reload?

Again thank you for your responses.

 

[Uthink Uknow]

Yes it can and firing it will fire form to chamber dimensions. That primer looks as though your firing pin hole in the bolt face is oversized. Can you take a picture of it? Can you strip the bolt of the firing pin and check for scraps of an earlier pierced primer?

 

[hrlincoln]

I spoke with the gun owner who explained that he can close the bolt on a PTG nogo gauge but if he adds a piece of tape (.002 as above) the bolt no longer closes. Is this dangerous? Can the brass be used to reload?

Again thank you for your responses.

If he can close the bolt on a NO GO gauge (without the tape), he has excessive headspace. Best to contact the builder for resolution.

 

[msinc]

If he can close the bolt on a NO GO gauge (without the tape), he has excessive headspace. Best to contact the builder for resolution.

Well, "the builder" has missed getting the headspace right....and turned him loose with a rifle that has a rougher than needed chamber and what appears to be an oversized firing pin hole in the bolt....I don't know if I'd be in any rush to contact him or not!!!! I think at this point I'd be contacting a real gunsmith.