.257 AI back from the Gunny

[MT Pockets]

I got my Model 7 Remington back from the gunsmith last month. With upper 90 degree temperature weather I have yet to get it to the range. I have loaded three boxes to fireform my new Nosler brass and am hoping to get that done this week. I am a bit dismayed at the lack of load data for this round. What I have loaded is a 120 gr Speer found at the local big box gun store. My rifle has a 20" 1-7.5 twist so it should be OK but I want to load in the 110gr to 117gr range. My question is where to begin loading after fireforming without IMR4350 and RL19 powder. I can't find it anywhere.

 

[SJB358]

I imagine a QL user can give you some useful data for the bullets you wanna use. Otherwise maybe just use Roberts data or Sierra AI data to work up with your chosen powders and bullets.

 

[JD338]

I started exploring the 280 AI almost 20 years ago. 280 Remington max loads are starting loads for the 280 AI. The 280 AI chamber was cut to give a slight crush on a 280 Remington case at the datum line so I never have had any issues fire forming my brass.
I would suspect the 257 AI to be similar.
Do you know how your gunsmith cut your chamber?

JD338

 

[Blkram]

Do you want to stick to the 58,000 psi pressure limit or bump up to 64,000 psi for in your Model 7?