Forming 17FB from 221FB and die preference

[GrocMax]

This has been posted on Saubier as well, I know a bunch of you small caliber nuts are over there as well.

For you veterans of forming 17FB from 221FB, what is your preference?

2 basic differences between 17FB and 221FB are the shoulder angle (30 vs. 23) and the shoulder diameter (17FB is ~.005" larger).

Use the 221FB bushing die and leave the shoulder a sloppy fit, or finish with the 17FB die and let the shoulder mushroom?

Is there a consensus on the best method?

 

[yotehater]

Tag.

I was doing some today from LC 13 .223 going to 221 Fireball first. Annealed, turned, to 17FB seater, trimmed to max, then I crushed the necks. grrr.

I stocked up on the Lapua 221 brass for a new barrel but want to get my learning curve down first. Looking online that hi plains brass seems a bargain. Even having to neck turn it.

 

[NorCalMikie]

Why not just neck down the .221 to to .17 and be done with it?
Do you think/feel the "shoulder angle" difference between the two makes that much difference?

 

[germanlongbow]

I have the original trim and form dies for 221 fireball to 17 mach IV. There is a slight difference between the old mach IV and new fireball. If you by 221 bushing dies you should be able to easily form to 17 fireball in three of four steps with bushings. I prefer to turn the necks a .0001-0.0015 to clean up the necks after full length sizing the new brass first. Then step down in bushings to desired size. Either system will work but I have turned to bushings the past few years. Most of what I shoot now a days are wildcats that require a bit of time to form: 6 and 6.5 saum from 300 saum norma brass, 20 Br from 6 br lapua, 20-250 from 22-250, 22-6mm AI, etc. The smaller the cartridge the thinner the necks, usually the easiest to mess up, go slow and lube. Almost everything I've formed develops donuts so my final stage is neck turn off the donuts then final form with end die. I've had good luck with this technique, its a bit time consuming but worth it in the end.

 

[GrocMax]

Thanks all-

Just using the 221 FL bushing die couldn't get them short enough at the neck/shoulder junction to chamber, takes a final bump to the top of the shoulder (no bushing) with the 30 deg 17FB bushing die, which mushrooms the shoulder slightly. Only lose about .005"-.007" case OAL. No donuts!! (yay!)

Using the 17 die for the last neck down steps shortened them more than I was comfortable with (more mushrooming) and was concerned about installing donuts.

Didn't need to neck turn at all, ends up with .003"-.004" neck clearance in a SAAMI chamber (.205"-.206" neck ID). Definitely need to neck turn 223 based brass.

 

[GrocMax]

Why not just neck down the .221 to to .17 and be done with it?
Do you think/feel the "shoulder angle" difference between the two makes that much difference?

Its probably that extra little radial clearance at the neck/shoulder junction of the 221 bushing die that made it not be able to chamber, had to bump it with the 17 die then all was well.

Get that cute little 20 TCM slaying squirrels yet?