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280 AI with head space issues.

My 280 Rem, a Remington 700 Mountain rifle, shot just under an inch with my reloads. It was easy to get there, and I didn’t think much of it.

A close friend shoots a 280 AI. I liked what his gun was producing, so, off the gun was sent to the same gunsmith that did his. The gun returns, and load development starts.... and I’ve struggled. Three different powders and a number of different weight bullets and manufacturers. Nothing better than 1 1/2”, and not even consistent at that. Even tried factory Nosler Trophy ammo that friends gun runs to 3/4”. Still an 1 1/2“ in my gun.
Being a bit frustrated, had the gun looked at by another gunsmith. First thing he did was strip the bolt, and get out his go/no go gauges. First gauge was the go gauge and all good, as I expected. When the bolt closed on the no go, made me bit sick.

So. He’s come up with options to bring it back into spec.
I’d like to have some input on what can or should be done to the rifle now.

And what conversation I should have with the gunsmith that did the original work.

I’m looking for input, I’ve posted this on another forum.

thanks in advance. Doug
 
It would have been nice for gunsmith #2 to tell you how far off it was but I suspect that is not the entire problem with the accuracy. I, as the owner, sure would have liked to have an idea on how far off it was.
Your fired brass can still be sized .002 shoulder bump and fix the headspace through reloading though that does not make up for shoddy work nor does it promise to fix the accuracy. That method would lend itself to finding the accuracy "problem" you are having by eliminating the headspace variable.

The term mountain rifle is not necessarily associated with accuracy. Check your action screws, check your scope base and rings to be sure they are tight. Make sure the scope didn't die. Try more loadings.
 
What gauge did second gunsmith use? 280 Rem and 280AI (SAAMI) are different. The AI chamber is .040" longer at the datum. Contrary to the Ackley "doctrine" of an AI minimum chamber being .004" shorter than its parent round, to facilitate a crush fit with factory rounds for fire forming.
 
Thats not your problem unless its way off. How far does the shoulder move forward upon firing? The gunsmiths particular reamer may be a different setup than the checking out gunsmiths gage. The 280ai is the most screwballed one of them all since nosler standardized it and left all the old wildcat stuff out there
 
Thats not your problem unless its way off. How far does the shoulder move forward upon firing? The gunsmiths particular reamer may be a different setup than the checking out gunsmiths gage. The 280ai is the most screwballed one of them all since nosler standardized it and left all the old wildcat stuff out there

The shoulder moves .006 forward when fired. It was new Nosler brass. Length of case did not get longer. I believe the gauge the new smith used was a Manson SAAMi 280 AI. Reading on E A Browns Site, even no go gauges are set different.

And you are spot on with the 280AI and SAAMI/Nosler/original Ackley 40* being a muddy mess. They could have called it 280 Nosler and everyone could know they’re different.
 
What gauge did second gunsmith use? 280 Rem and 280AI (SAAMI) are different. The AI chamber is .040" longer at the datum. Contrary to the Ackley "doctrine" of an AI minimum chamber being .004" shorter than its parent round, to facilitate a crush fit with factory rounds for fire forming.

I called the old gunsmith. He didn’t know which reamer he “rented”. He said they send a no go gauge with the reamer. And with that.... I’ve sent an email to the rental company. Hope they know more than the old gunsmith. He also said he did not set back the barrel. He said it didn’t need it.
 
If it only moves .006 forward and everything else looks good and your die can size the brass after firing it shouldnt be an issue

I did find out it looks like it Was reamed with original type reamer and the barrel was not set back. I talked with the original gunsmith. So, at this time it looks like it’s not on the new Nosler SAAMI standard. That being said, I personally do not have a problem not shooting factory ammunition. I’ve ordered a Lee three die Set made for the original 280 Ackley.
 
I did find out it looks like it Was reamed with original type reamer and the barrel was not set back. I talked with the original gunsmith. So, at this time it looks like it’s not on the new Nosler SAAMI standard. That being said, I personally do not have a problem not shooting factory ammunition. I’ve ordered a Lee three die Set made for the original 280 Ackley.
Well the original design did require a setback but i think youll be fine as long as you know what you have. If those lees do not work you can call redding and they will make you the originals that i know will work with what you have
 

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