260 AI headspace

[scope eye]

Hi I sold my 260 ai barrel so I took it off they action, but the guy changed his mind and ended up getting another barrel I had, so when I went to put the barrel back on they action I remembered when I put it on the first time I had to pay a gunsmith to do it since I could not find any 260ai gauges anywhere, I usually have no problem setting headspace and I have all the popular chamberings, but my 243-308 set is not right, I heard there is a way to set it with a standard set but can't figure out how.

Tanks Dean

[rjtfroggy]

Don't quote me but I think the 308 no go is the go gauge for ai and then the .002-.003 shim on that for the no go.

[scope eye]

Thanks hope others chime in, there's a lot 260 AIs out there someones gotta know,

Dean

[hcpyro13]

The 260 go gauge becomes the no-go gauge on the 260AI, you need to get yourself a 260AI go gauge. I called ptg direct when I needed mine and only had to wait for shipping. After my dealings with PTG I call them directly, they have had everything I have needed in stock when none of the catalog suppliers did.

-J

[stangfish]

If you have a piece of 260 AI brass that was shot in the gun but has not been resized, chamber it, snug up the barrel against the shoulder, lock her down where the bolt is a little snug to close. You have have now tightened up your headspace - .0005. or less than it was before you took the barrel off. Worst case scenario you bump the shoulder back .001 on resizing to loosen the bolt. Yeah all the smiths and book worms say no but if you know what your doing as a reloader this aint no step.

[bootsmcguire]

If you have a piece of 260 AI brass that was shot in the gun but has not been resized, chamber it, snug up the barrel against the shoulder, lock her down where the bolt is a little snug to close. You have have now tightened up your headspace - .0005. or less than it was before you took the barrel off. Worst case scenario you bump the shoulder back .001 on resizing to loosen the bolt. Yeah all the smiths and book worms say no but if you know what your doing as a reloader this aint no step.

+1, I have been been using this method for quite some time. Keep that brass you use seperate so if you need it again down the road, you are keeping things consistant. I have been pondering the idea of injecting epoxy into a pc. of fired brass for each of my barrels to create my own custom Go-Gauge specific to my chamber. This way there is no risk of accidently tightening up the barrel too tight and shoving back the shoulder on my gauge. Just a thought.

[bsekf]

I have a reference mark on the barrel nut, and before I remove a barrel I put a mark on the barrel, as close to the nut as I can get it. I use a sharp prick punch. Then when I replace the barrel I have a reference. I still use a fired case for go and 2 pieces of tape for no-go. The reference marks make it very evident if I am a full turn off.

[scope eye]

Will a 260AI gauge also work on a 243AI? To make it less of a hit to buy.

Tanks Dean

[maclowry]

Good info
I'll tag this

[bootsmcguire]

Will a 260AI gauge also work on a 243AI? To make it less of a hit to buy.

I do believe they are the same.

[BillPa]

I do believe they are the same.

Without going into all the gory details, no, they are not the same. The 260 Rem is .025" shorter from the casehead to the neck-shoulder junction than the 243 Win., where the correct cartridge head clearance is established for firing the parent in an rimless bottleneck improved chamber. Using a 243Imp GO would result in roughly .029" ( .025 plus the .004" crush) short head clearance in a 260 Imp chamber.

Bill

[bootsmcguire]

Without going into all the gory details, no, they are not the same. The 260 Rem is .025" shorter from the casehead to the neck-shoulder junction than the 243 Win., where the correct cartridge head clearance is established for firing the parent in an rimless bottleneck improved chamber. Using a 243Imp GO would result in roughly .029" ( .025 plus the .004" crush) short head clearance in a 260 Imp chamber.

Bill

Thanks for clearing that up. Sorry for being wrong, but it happens to us all I guess.

[BillPa]

Thanks for clearing that up. Sorry for being wrong.

Hey, no biggie Boots. I just like to offer what I've learned over the last forty years play'n with weird stuff! I built my first better one in 1971, a 280 Imp.

Just to elaborate a bit further, using the 308 family for instance......



Although they all share the same length case head to shoulder datum in their original configuration the case head to the neck shoulder junction varies due to how far the neck diameter protrudes in the the shoulder. As the amount of protrusion increases or decreases it changes the cartridge head clearance in an improved chamber.

Since the design of a improved cartridge is the ability to chamber and safely fire the parent without alteration it requires the cartridge to seat on the junction with a crush fit, the body and shoulder are hanging out in the wild blue yonder!


With that maybe it helps to understand why gages for improved rimless bottleneck cartridge are unique and not the same with cartridges even in the same family.

Bill