243AI question on fireforming

[Sheep Hunter]

I have a 243AI that is shooting lights out. The load is 45Grains of RL22 toped with a 105gr berger.

It seems to be a little tight when the bolt is closed with the fireformed brass. My question is what steps do you take after fireforming the brass. And if there are no pressure signs should I change any thing. I am using this gun for hunting so I do not want any loading issues in the field.

[adam32]

Are you full length or neck sizing them after they are fire formed?

[Sheep Hunter]

I am full length sizing, but only bumping it back 1thou. I am also trimming the neck to make sure they all start out the same length.

Thanks

[J E Custom]

Originally Posted by Sheep Hunter

I have a 243AI that is shooting lights out. The load is 45Grains of RL22 toped with a 105gr berger.

It seems to be a little tight when the bolt is closed with the fireformed brass. My question is what steps do you take after fireforming the brass. And if there are no pressure signs should I change any thing. I am using this gun for hunting so I do not want any loading issues in the field.

It is normal for the fire formed case to be a little tight because it has
no headspace and totaly fills the chamber.

If you want to avoid loading issues for hunting back off on your sizing
die just a little untill you get the desired fit.

If your neck sizing only it want help with the feeling of tightness.

J E CUSTOM

[Sheep Hunter]

Thanks J E.

[338hammer]

I am thinking that if one has a tight chamber then one has what could be called a benchrest quality chamber. When you say tight we really do not know what tight is unlee you say its leaving fine powder from the case on the bolt head. Maybe a bolt smear on the head of the case.
In any cartridge if its tight, screw the die down tighter to the shell holder until the issue goes away. If the issue does not go away call your smith.

Set back is normal when forming a factory case to an improved chamber. After the set back/headspace is correct then I use a neck die only. Careful about going to far in the set back as one can bulge the neck/shoulder juncture and make a tight fit as well. Typically when fire forming for the break opens I will have to set the shoulder .015-.020 back.

338

[ddgo]

Sheep hunter I have a 6mm AI tight neck that has had the same issue. I got a standard neck full length sizing die from Redding. The die will not size the necks on the tight neck, but it will bump the shoulder back to allow easy bolt closing. I use a set of redding shell holders that are different thickeness. Setting the die against the shellholder i find the one that allows for the feel that I want in closing the bolt.
I then go back and size the neck with a Wilson bench rest die with the proper sizing bushing. This gives me the perfect fit I want.
Hope this helps. ddgo