50 or55 gr buulet? What do you feel would be better for a 22-250 ack imp.Also do you think 1 inch groups while fireforming is respectable?does accuracy improve after fireforming?

To start with, one inch groups while fireforming is plenty good. When fireforming for my 22-250 AI, I just go out and kill a bunch of varmints with it. Whether or not the groups will improve just depends on the gun and the loads. Some AI chambers shoot fireforming loads about as good as anything.

In regard to the choice of either 50 or 55 grain Ballistic Tips, it sort of depends on the barrel.
I have had a hard time getting 55 grain Nosler Ballistic Tips or Sierra Blitzkings to stabilize in 1 in 14 inch twist barrels. The 55 grain V-Max bullets seem to do better. In most all cases, I have had better luck with the 50 grain BT's in any number of 22-250's and 22-250AI rifles.

I have spoken to the folks at Nosler and Sierra and they readily admit that their 55 grain plastic tipped bullets are so long that they are often not stabilized in 1 in 14 inch twist barrels. The darned Nosler version is right on the ragged edge. They shot like crap here in CA at 300 feet elevation. However, at Nosler's suggestion I went ahead and took them to South Dakota and shot prairie dogs at around 3500 feet elevation and they did just fine. (Believe me, I took lots of other bullets along in case they didn't.)

Actually, myself and several friends have just about decided that for the most part 50 grain bullets are generally more accurate in 22 caliber center fire rifles than 55 grain bullets anyway.
Just read some of the old articles Bob Hagel wrote about the fantastic accuracy he got with the plain jane 50 grain Sierra spitzer. That is one heck of a good varmint bullet, you do not need a plastic tip to hit things.

R F

Shoot the one that shoots best in your gun. There's not much difference in the game either is appropriate for, and the higher velocity of the lighter bullet is somewhat offset by the higher ballistic coeffcient of the heavier bullet.

One inch groups with fireform loads are about 1/2 inch better than groups from average rifles with factory loads, so yes, I'd say they're pretty good.

You certainly shouldn't expect your best accuracy from fireforming loads, but it is entirely possible to have some loads that are less accurate with formed brass. That's why you have to work loads up and tailor them to your gun.

Guys, I used to use 55 Noslers BTs with IMR 4064 @ 36.0 with good accuracy. Cost forced me to VMax 55s with same charge and I have had great luck with them in my Rem 700 VS. They cluster with all touching consistantly with a cool down after three shots. They do the job on chucks making a redish spray on impact.
Tac

Depends on bore twist in your rifle as to waht weight bullet shoots best. Most 22-250 rifles have 1 in 14" or 1 in 12" twist rate. My 22-250 with 1 in 12" twist bore shoots very tight groups with bullets up to 60 grains. I use the 60 gr. HP for all my chuck shooting in my 22-250. The heavy bullet performs better at longer range shooting.
There are exceptions to every rule and your rifle will tell you what bullets it like best. Short stubby bullets like slow twist bores, long bullets like faster twist bores.

I use both the Nosler 50 and 55gr. Bal. Tip in 4 different .224 rifles. Both bullets shoot
well in each rifle. In fact, they are the only non hollow point bullets I do use. Nosler has
come a long way with their Balistic Tips. I'm starting to use them in other larger calibers from .243Win. to .308Win. and in all cases I'm more than satisfied. Best wishes.

Cal - Montreal