When converting from a standard caliber to an "improved" (Ackley type)can the original barrel be used, or must you rebarrel? Assume a standard factory barrel in .260 Rem. I know that reamers differ slightly by manufacturer, would it be enough that you should just rebarrel, or since the case draft is changed will this eliminate any problems from using a different reamer? Thanks for your help.

Doug-

On that conversion, you should be fine. However, for probably not more than an additional $150 or so, you can have your 'smith install a new higher quality (as opposed to factory) barrel. Something to think about.

If you're happy with your barrel though, an AI reamer should clean your chamber up nicely with minimal fuss.

Have fun!

Dodgy Doug,

The only problem I can see is if your Improved reamer has a slightly narrower neck. In this case, you will end up with a small step on your Improved brass.

I have seen it happen. It only requires the barrel to be set back a bit if this happens.

A new barrel, as Gary suggested, might be a better idea.

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saeed@ emirates.net.ae

www.accuratereloading.com

When I rechamber Ackley imp. I ALWAYS set the barrel back a thread in order to achieve the correct head space for the improved version & more importantly to still be able to fire factory ammo in the gun without case head seperation. Also while the barrel is off the action lap the lugs & square the receiver.

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Thanks to everyone for the great information. This is one area that I know very little about, but find fascinating. Your suggestions have all been helpful. Thanks again

The barrel should be set back at least on thread, preferably two for a couple of reason.

The first is to insure that if you have a really sloppy factory chamber, it gets cleaned up. It also gives the smith the oportunity to throat it for a specific load (for instance the 107 gr Lapua Scenar in a 6mm Ackley Improved loaded a lot longer than SAAMI standard cartridge OAL)

Secondly, a correct Ackley chamber is about .002 to .004 shorter than the standard chamber. This is so that the cases about to be fireformed are pushed up against the neck/shoulder junction of the chamber and held firmly in place to help prevent seperations. In effect, a 6mm Rem go-gauge would be the no-go gauge for a 6mm Ackley. There are a lot of "improved" chambers out there called Ackley, but P.O. was a pretty shrewd old boy when it came to chamber designs and he didn't really advertise why he did a lot of things the way he did. That slightly shorter chamber marks a true P.O. design.

Thanks Rust, Your information, along with everyone elses, is going into my log book. When I have my 260 AI built I'll put this information to good use. Thanks again for the info.