Reloading for 257 AI

[rf2]

Hello, I'm very new to reloading - I've read quite a bit about the hobby and I've put together 20 rounds for my 30-06 with some good results, but that's it.

I've purchased a rifle in 257 AI - it's a custom gun built on a 96 Swedish Mauser action with a heavy contour barrel and some other customizations. I picked up some 257 Roberts +P brass (257 Roberts factory ammo was way too expensive), so I am just about ready to reload for this gun. My plan is to load up the +P brass with H4350 and Hornady SST 117 grain bullets because that's the powder I have used previously, and I would like to shoot the 117 grain bullets possibly for deer hunting.

I have a few questions however.

1 - I seem to remember reading that for fireforming with a projectiles, it's best to use faster burning powders with lighter bullets. Is my plan described above potentially unsafe (heavy bullet, slower powder)? I thought it would be fine since apparently you can just use factory ammo to fireform without any concerns, but now I'm having second thoughts.

2 - I made up a dummy round with the long 117 grain bullets, and seated the bullet to the cannelure (because that's what my reloading manuals suggest as the seating depth). The round fits in the magazine fine and chambers in the gun, but according to my Lyman manual the total length (2.877") is longer than the SAAMI max length (2.775"). Can I just disregard the SAAMI max length? Is it because the action is originally for the 6.5X55 Swedish Mauser round that the cartridge fits in the magazine even though it is "too long"?

3 - I have a RCBS 257 AI die set (40° shoulder) which only comes with the full length die and the bullet seating die. I would like to extend the brass life as much as possible, because it was not that easy to come by. Should I purchase a Lee collet neck sizing die. Would a 257 Roberts collet neck sizing die work, or would I have to purchase one (custom) for the 257 AI? (EDIT: Based on the Lee diagrams for their collet neck sizer dies, it seems like a 257 Roberts collet neck sizing die would screw-up the shoulder on 257 AI brass - correct?) Or can I just neck size by backing out the RCBS full length die?

Any input would be appreciated.

 

[Sask_Hunter]

I used one of the 4895 powders to form over 200 257AI and 100 6.5x55 cases with out a problem. Take any load with 4895 and a 100-120 bullet that's listed with that bullet weight and seat it so it's in to the lands, the case needs to be seated tight against the boltface.


To answer question two, SAAMI specs for loaded overall weight is not an issue, if your chamber can handle a longer length and the magizine can also handle the length then load to it.

For your die question just turn out the sizing die so it doesn't bump the shoulder back, you only need to size the first 3/4 of the neck. Use a marker and mark the neck, run it through and look for the ring it leaves. I trimmed my cases after I fire formed and have needed to since.

Any of the 4350's, 4831's Reloader 17, 19 and 22 have worked well in my 257AI.

 

[KDX]

Congratulations on buying a rifle with the most excellent chambering on the planet Earth. Here's a post I did a while back on fire forming the same brass. Link I took my chronograph out last week and had a 5 shot average of 3735fps with a 75gr V-Max, 45gr of XBR and a Winchester magnum rifle primer. That's faster than a 25-06 by a wee bit and it's using less powder. Here's a link to an interesting article in Handloader magazine.

 

[rf2]

Congratulations on buying a rifle with the most excellent chambering on the planet Earth. Here's a post I did a while back on fire forming the same brass. Link I took my chronograph out last week and had a 5 shot average of 3735fps with a 75gr V-Max, 45gr of XBR and a Winchester magnum rifle primer. That's faster than a 25-06 by a wee bit and it's using less powder. Here's a link to an interesting article in Handloader magazine.

Just wondering, why did you use magnum rifle primers?

Also, is there any point to playing around with powder charges while fireforming? I figure "no" because the final case capacity will be different once the cases are fireformed, so I'll basically have to start over. On the other hand, it might get a bit boring/discouraging if I'm always firing the same load for 50 rounds, especially if it's not producing good groups. On the "other" other hand, I'd probably get more uniform cases by using the same load.

 

[KDX]

I used magnum primers because I accidentally bought 1000 of them and the store is a 300km round trip to take them back. I asked around on here and the common consensus was that it was OK. I used the max load (Hodgdon) of H335 for fire forming because I have 3 pounds or so of it on hand and figured I need to use some up. My fire forming loads were actually quite accurate also.

 

[rf2]

Take any load with 4895 and a 100-120 bullet that's listed with that bullet weight and seat it so it's in to the lands, the case needs to be seated tight against the boltface.

This makes perfect sense, but I have never read that you have to seat the bullet against the lands when fire forming the AI brass. Does everybody else do this?
If you are fireforming using factory 257 Roberts ammunition, you don't have to do this. Why not?