Headspace issue????

Fore300

Fore300

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Just got a new barrel spun on my 260 and trues the action. Wanted to load up some rounds and found the over all length significantly shorter then previous or Sammii spec.
SAMMII States max OAL is 2.800, max I can go is 2.750 and that has the bullet touching the lands.
Still loaded up the shorter rounds. At the range found that it was difficult to Chamber a round (brass was full length sized , trimmed , chamfered,) had to use pressure to lock the bolt. After shooting I had to tap the bolt with my hand to get it to move back.
Came home to try resizing my brass. Removed the ejector from the bolt to find the sweet spot. With the Forester Die fully bottoming out the brass still has a slight hang up on the bolt.

Would this mean the chamber is to shallow? Does it need to be cut deeper or just leave it like this
 
Does a FL sized piece of brass chamber ( no bullet seated).
Also, I think you are not understanding SAAMI as it applies to chamber dimensions ... not the COAL with a seated bullet. Different bullets will engage the lands at different lengths...depends largely on the length of the bullet and the shape of the ogive.
 
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JEC said:
Does a FL sized piece of brass chamber ( no bullet seated).
Also, I think you are not understanding SAAMI as it applies to chamber dimensions ... not the COAL with a seated bullet. Different bullets will engage the lands at different lengths...depends largely on the length of the bullet and the shape of the ogive.
Click to expand...

It will chamber a FL brass but is slightly stiff. After a round is shot it is very hard to get the bolt back. I have chambered a spent piece of brass from today, it is also stiff going in and very hard to get the bolt back like it is locked in
 
Will it accept new unfired brass?
Was the brass you are using previously fired in another barrel?
Have you tried it with Go and No Go gauges?

When the action was trued, were the rear surfaces of the locking lugs, and the corresponding locking abutments in the receiver recut? How is primary extraction?
Was it a prefit barrel, or was the chamber cut by the 'smith?
 
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tiriaq said:
Will it accept new unfired brass?
Was the brass you are using previously fired in another barrel?
Have you tried it with Go and No Go gauges?

When the action was trued, were the rear surfaces of the locking lugs, and the corresponding locking abutments in the receiver recut? How is primary extraction?
Was it a prefit barrel, or was the chamber cut by the 'smith?
Click to expand...

Hello,
I don't have any unfired brass unfortunately so I am not able to check that. The brass was all fired in the previous barrel and has been full length sized and trimmed
I also do not have any go no go gauges so am not able to check
The lugs and reciever were both cut and the barrel was chamber cut by the Smith.
Only issue with extraction is after the rifle has been fired, you can lift the bolt but can't pull it back. Like it is locked on something. I can reproduce this by chambering the fired brass it will go in, lock and then hard to pull the bolt back
 
It is possible that when the locking lugs and abutments were faced off, primary extraction may have been compromised or reduced.
When you open the bolt slowly, how far does it rotate before the primary extraction camming begins?
Hard extraction could result from a less than smooth reaming job.

Following standard practice, the 'smith should have reamed the chamber until it closed on his Go, but not on his No Go. This chamber will have nothing to do with the chamber in the previous barrel. A FL die may or may not size cases down to unfired specs. I assume that he test fired the rifle.

Cartridge overall length depends on when the bullet's ogive contacts the rifling leade. Different reamer, different overall length.

I would suggest trying new cases or factory ammunition - see if it fits.

By all means call the 'smith, and report the problems you are experiencing.
 
tiriaq said:
It is possible that when the locking lugs and abutments were faced off, primary extraction may have been compromised or reduced.
When you open the bolt slowly, how far does it rotate before the primary extraction camming begins?
Hard extraction could result from a less than smooth reaming job.

Following standard practice, the 'smith should have reamed the chamber until it closed on his Go, but not on his No Go. This chamber will have nothing to do with the chamber in the previous barrel. A FL die may or may not size cases down to unfired specs. I assume that he test fired the rifle.

Cartridge overall length depends on when the bullet's ogive contacts the rifling leade. Different reamer, different overall length.

I would suggest trying new cases or factory ammunition - see if it fits.

By all means call the 'smith, and report the problems you are experiencing.
Click to expand...

Yeah I am calling him today to go over it, just was trying to see if I was missing something small before I go back.
Thanks for the help
 
Congratulations, you probably have a rifle that has a chamber cut to its smallest possible dimensions for the best potential accuracy. The brass which sounds like it came from a different rifle has been 'fitted' to that old rifle's chamber which sounds likely to have been mass produced and pretty much at maximum possible dimensions.

So, first off, SAAMI has nothing to do with COAL or CBTO. It is all about the case and the chamber. COAL is all about magazines. If it don't fit in a mag it won't work in your rifle unless used in single shot hand fed mode. CBTO is about the casing base to ogive on the bullet. This length is what you set to ensure that the ogive iin normal loadings is off the lands.

You need to worry about the overall case length, and the CBTO as well as the COAL, but more importantly, the casing base to shoulder length.

Since this is all once or multiply fired brass and resizing isn't working it could be case hardened and not being fully resized due to springback. Buy some new unfired brass and chamber it without loading or firing it. Brand new brass is almost always as small in ALL dimensions as it will ever be. Does the new brass chamber and extract properly? Measure where your lands are and adjust the seating depth so that the ogive on the bullet is at least 10thou off. Load up 5 or so and take them to the range. Do they fire and extract properly? They will now be about 90% of what will be the fireformed chamber dimensions of your new rifle's chamber. Measure all five casing base to shoulder. Yes you will need the proper tools to do so, Hornady makes some more than adequate stuff. You can use the same tool with different inserts to measure CBTO properly. Measure 5 of your previous resized cases. The old cases must be the same length or shorter than the truly once-fired new cases or they will NOT chamber properly which appears to be the current case.

Resizing - maybe your die isn't doing enough of it. It could be that you might require a small base sizing die. This allows the die to come down to the web area of the brass a little further and push the shoulder back more. The same action can be done by extremely CAREFULLY and ever so SLOWLY hand sanding, on a flat piece of emery cloth, the upper surface of a shell holder down in increments of around 0.002" and redoing the resizing, until the empty brass chambers properly. I say carefully as the upper surface of a shell holder must remain flat and parallel to its base. Emery cloth flat on the work surface. Light pressure on teh shell holder held so that the top is on the emery cloth and rotate a tiny bit every stroke or two with constant cleaning and measuring.

On top of this, it could be that the neck and shoulder is suffering from the work hardening as well during prior firings and will not resize properly.

My opinion. Buy some new brass. Load it up and shoot it. I bet it works perfectly. You can figure out what is wrong with the old stuff later.
 
I buy bulk once fired military 5.56 and 7.62 Lake City brass fired in a multitude of different chambers. And all this brass is resized with a small base die and the cases are returned to minimum SAAMI dimensions.

Bottom line your cases were fire formed to your original chamber and even after sizing the brass tries to spring back to its fired size.

Dies and chambers vary in size and a case fired in a "fat" chamber when resized will squeeze the shoulder forward more when resized.

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Below are three .308 resizing dies sold by Forster for different sizing needs.

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There is one thing more your can try, full length resize the cases again and pause for 4 to 5 seconds at the top of the ram stroke. Meaning keep the case inside the die for 4 to 5 seconds before lowering the ram. This reduces brass spring back after sizing and case diameter and headspace length may remain smaller. If this does not help you may need a small base die to reduce these cases to minimum SAAMI dimensions. You need to check to see if its a case diameter problem or if the shoulder is not being pushed back far enough or both problems. Or simply buy new brass and not be bothered with your old brass.
 
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Ended up coloring a piece of brass to see where the issue is and found it was at the web of shell. It has a slight ridge from the previous factory barrel and the full length die doesn't size this portion or at least without modifications and pushing the shoulders way back.
New learning experience for me. Thanks for everyone's input it helped a lot
 
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