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- Thread starter Riflechair
- Start date
A tight chamber will not increase pressure. A tight bore or neck might or Win .308 factory ammo can in a 7.62 NATO chamber.
I use tight chambers in my match guns that require small base resize dies. Normal factory ammo will go in those chambers.
You need to have proper head space gauges to truly check headspace.
Could be the steel cased ammo is oversized for that chamber.
BTW, I've seen some of your youtube vids. I like them.
I use tight chambers in my match guns that require small base resize dies. Normal factory ammo will go in those chambers.
You need to have proper head space gauges to truly check headspace.
Could be the steel cased ammo is oversized for that chamber.
BTW, I've seen some of your youtube vids. I like them.
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First stop using that crap steel ammo in an expensive rifle...
Then take the rifle back and indicate you would like the headspace checked and that factory ammo is showing what you consider excessive pressure... but cratered primers and flattened primers are not necessarily due to excessive pressure.
It isn't excessive pressure unless you have hard bolt lift...
Then take the rifle back and indicate you would like the headspace checked and that factory ammo is showing what you consider excessive pressure... but cratered primers and flattened primers are not necessarily due to excessive pressure.
It isn't excessive pressure unless you have hard bolt lift...
How have you measured your brass? What tools did you use? Which measurement is 2 thou under SAAMI?
Pierced primers on a factory load indicates a problem. Should not have high pressure with a factory load. You should have them check the bolt face for damage too...
The NATO cartridge can be up to 0.013" longer so it makes sense that it would not fit in a SAAMI chamber toward the tighter end of the tolerance for headspace.
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Mystic Precision
CGN Ultra frequent flyer
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RC, sorry to hear of your woes but from a competition rifle stand point, I would be happy.
As a "high end" rifle, the assumption may be that the shooter is a reloader and will cater to the chambers dimensions. There is a very good chance that the chamber is cut near or at min SAAMI spec and those dimensions may continue into the neck and throat. If this is what has happened, YES, typical factory ammo can show pressure signs.
First check, can you drop a bullet into the fired case neck or does it stop or not even enter? Check the necks for burrs from the industrial trimming process.
Is there a rub mark around the base of the case where the case web would be? Is there a rub mark around the shoulder/neck area?
Does the fired case show stretch marks in the case body? colour now dull with very fine lines all around the mid portion of the case?
What was the factory ammo?
If you plan to use factory ammo in this rifle, maybe a looser chamber is in order or different ammo. If you are going to handload and do a bunch of prep, you may just have a great shooter.
If the action is strong and the lock up is good, there is performance available not typical of reg factory rifles.
Send me an email if you want to discuss further.
Take care....
Jerry
PS, I wouldn't be using surplus ammo as a headspace gauge... I wouldn't use factory ammo either
What measurement do you get for an unfired factory load? For the factory fired case? I know you said the fired cases were 0.002" less than SAAMI, but I am wondering if they got longer or shorter when you fired them?
A tight and minimum tolerance chamber will most definitely cause a big increase in pressure and the problems you are getting if the brass is longer than the chamber and causes the mouth of the brass to compress or hold the bullet too tightly on firing.
A minimum tolerance chamber will give you much better accuracy than a loose chamber but you will probably be best with only using handloaded, fire formed and properly trimmed brass that does not compress the bullet when the bolt is forced close and allows the bullet to release on firing normally.
A minimum tolerance chamber will give you much better accuracy than a loose chamber but you will probably be best with only using handloaded, fire formed and properly trimmed brass that does not compress the bullet when the bolt is forced close and allows the bullet to release on firing normally.
