243 Win vs 243 AI

[Jsn_leonard]

How much accuracy would you loose out on by shooting 243 Win ammo out of a 243 AI? The guy I got the gun from told me he thought it’s an Ackley but wasn’t sure. It’s a rem 700 action with a 24” heavy barrel. I’m unsure of the twist rate an am shootin Barnes 80gr TTSX. It’s not shootin bad but I think it should be grouping a little tighter. Here’s the before an after brass. Thanks!

 

[deerkiller]

How much accuracy would you loose out on by shooting 243 Win ammo out of a 243 AI? The guy I got the gun from told me he thought it’s an Ackley but wasn’t sure. It’s a rem 700 action with a 24” heavy barrel. I’m unsure of the twist rate an am shootin Barnes 80gr TTSX. It’s not shootin bad but I think it should be grouping a little tighter. Here’s the before an after brass. Thanks!View attachment 117570

you will probably lose a little velocity to pressure loss from the case reforming but I doubt it'd be much - I couldn't begin to count the PD's and rock chucks I've killed with fireforming loads from a 243 AI but it's a whole bunch AND PD's too with 223 AI fireforming loads
243 AI is one of PO's better conversions

 

[Cahunter805]

That’s definitely an AI chamber. Is it a slight crush fit when you chamber a factory round?
An AI chamber is usually shorter than the standard so when fire forming the shoulder/neck forms well.
AI forming loads normally are pretty accurate. I’d shoot up some factory ammo then reload and see what your AI likes. If you handload you can also load forming loads for plinking/varmints then use the brass for hunting loads. It should be about 100-150fps faster if not more vs factory loads and might be more accurate.

 

[deerkiller]

That’s definitely an AI chamber. Is it a slight crush fit when you chamber a factory round?
An AI chamber is usually shorter than the standard so when fire forming the shoulder/neck forms well.
AI forming loads normally are pretty accurate. I’d shoot up some factory ammo then reload and see what your AI likes. If you handload you can also load forming loads for plinking/varmints then use the brass for hunting loads. It should be about 100-150fps faster if not more vs factory loads and might be more accurate.

it's not technically a "crush" fit, you want to SLIGHTLY force the ogive into the lands to prevent the case from slamming backward into the boltface to headspace which will stretch the web and weaken the brass but After fire forming you are good to go with THAT brass - Be aware that when pushing the bullet into the lands, IF you try to unload that unfired fireform round you might pull the bullet and dump the powder into the action = BIG MESS