Headspace - too tight?

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peterdobson

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In trying a new Rem 700 SA - Krieger 6.5X47 Lapua there was "more than normal" pressure required in closing bolt as compared to factory barreled action.

I remember an article in Precision Shooting advising against too short headspace and that this pressure can actually end cartridge case. This is gunsmithing but also precision rifle.

Any comments?

Peter
 
I presume that the shoulder to boltface dimension is a bit short, and this results in more effort being required to close the bolt, the cartridge case being squeezed lengthwise. Once fired, the case should be fireformed.
How does the bolt feel on the GO gauge?
Might be an idea to do a little more reaming?
 
Are you closing the bolt with no cartridge, if so it is a rifle issue.

If there is a cartridge under the bolt then it is a sizing issue.

If the chamber was cut a bit short, as you can still close the bolt, adjust size die, worst case take a few thou off the bottom of the size die.

This will adjust the base to datum line distance as well as reduce body diameter somewhat.

Just the inverse of to much headspace, eg: forming 280ai brass from 270Win brass, the 270 will have excessive head space but producing a false shoulder will attenuate the issue for fire forming in the 280ai chamber.

The interior volume of the case may be somewhat smaller, but 'good practice' handloading will keep you from unexpected high pressure.
 
Years ago I was given a rifle by my uncle, it was a reworked military mauser in 257 Roberts. Brand new cases would not enter freely, if I took a new case and sized it, turned it 90 degrees and sized it again, then it would work. Instead of doing this, I took a case holder, shortened it .002 in a lathe, and then it was just a case of resizing like any other brass.

I see a manufacturer is advertising case holder sets that have been shortened by .002 an d .004 and so on. Why not try a set of these holders and use the one that works. If your chamber is a bit short and you fit your brass to the chamber, I don't see a problem with it.
 
Thanks, we are closing bolt on new Lapua ammunition which we should have mentioned. Could be issue of difference between go gauge and Lapua ammunition specs? We don't due gunsmithing, so not aware of how gauge felt.
 
If you are certain the bullet is not into the lands, I would guess you have negative head clearance due to contact at the shoulder. Now, whether this is the result of a rifle chamber too short or some ammunition which is too long, I can't say without being able to measure either one. It is also possible that the headspace measurement, at the datum line, can be perfect on both but the shoulder angle on one of the other is a little off.
 
You will have to compare it with a steel go gauge to determine if it is the rifle or ammo at fault as far as the hard bolt closing. Smoking the case and bullet may give an indication of where the interference is.

If you can feel the bolt on a go gauge it should be only at the very bottom of the bolt throw for an absolute minimum headspace. It certainly doesn't hurt to be a bit looser.
 
Agree with both Leeper and guntech. Even the mighty Lapua has brass that isnt in spec from time to time. Possible neck clearance issue? Get a headspce gauge and go from there.
 
Tight neck maybe? I had the same thing with my 6x45 lapua brass. Even after necking up had to turn necks. Never had to with any other brand of brass (R-p, hornady, winchester)
 
Peter, is it also tight on new empty brass ( 4PH6010 ) or just the loaded factory ammo?

I think it's more likely to be something with the chamber/reamer than anything with the factory ammo size.
 
SND said:
Peter, is it also tight on new empty brass ( 4PH6010 ) or just the loaded factory ammo?

I think it's more likely to be something with the chamber/reamer than anything with the factory ammo size.
Click to expand...
This issue of new brass vs reloaded brass is a good question. Soft,annealed, brass can be stretched quite a bit by the expander ball if it is a little tight when withdrawing it. This wont happen with Lee 'collet' dies fwiw
 
It is tight with factory ammo but not new cartridge case aka brass. Perhaps leade is too short - John Marshall will check. Ammo is Lapua 6.5X47 Lapua 123 grain.

Regards,

Peter
 
Smoke the bullet and try it, or a black felt pen ... rifling marks should be quite visible if the bullet is jammed. Then pull that bullet and try it again... should be a big difference in feel...
 
whose reamer print was used to cut the chamber and what was the reamer spec'd to? if the reamer was spec'd for a 140 grain VLD and your trying to load a factory 123 grain scenar I am going to wager a bet that you've got somewhere around a 47 thou jam going on, and or the reamer was spec'd for the 123's seated just off the shoulder/neck junction where as in factory loaded ammo it is quite likely loaded much longer
 
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