Any pitfalls to be aware of when making 20VT cases from 223 cases?

[BaconFat]

Even though my current crop of 20 VT cases were made from 221FB I thought I try my hand at forming them from .223 cases. I read the thread by the guy from NZ on how he does it and I pretty much followed his steps.

My method to create these cases is the following:

1. Redding 221FB form die #1 to partial form neck.

2. Redding form/trim die to finish neck and create shoulder.

3. F/L size with Redding 20 VT die.

4. Cut neck down to a manageable length.

5. Use Wilson neck trimmer and trim case to 1.399. Will have a WFT on Monday because the Wilson trimmer is too time consuming to use.

6. Clean cases to remove trim shavings.

7. Size neck.

8. Expand neck with PMA expander mandrel.

9. Turn neck to .013" with PMA neck turner.

10. Chamfer and deburr.

11. Clean cases again to remove shavings.

12. Anneal with Bench-Source annealer.

Some may think I'm cleaning the cases one time too many. I have contaminated my bushings and other stuff with brass shavings before so I've taken steps to separate my

trimming/turning area from the rest of my reloading space and a little quick wash doesn't take too long. One of the things I'm not sure of is my trim length. The chamber in

my rifle is 1.410" which should give me .020" of clearance. I have read that during fire forming the OAL length will decrease a little when the shoulder is properly formed

which is why I went with the noted length in step 5.

 

[L-46]

I am sure you have covered it,
But if not deburr the internal flashhole before necking to 20 cal, saves buying more tools.
also check the base diameter of your new cases with your chamber, being the reamer might have a parent case of the 221 which can vary from the 223 base size?

 

[BaconFat]

... But if not deburr the internal flashhole before necking to 20 cal, saves buying more tools.

This is the kind of suggestions I was looking for. I bought a flashhole deburrer for these cases, but since I save the deburring

step for near the end, after necking down to 20 cal, it didn't fit. :-\ So I thought, here's another piece of equipment I've

purchased that I can't use. Well, I checked a case from my box of Lapua .221FB and bingo, the deburrer slips through the

neck like a glove. Of course Lapua cases don't need this done, but I do have some virgin LC .223 cases on the way.

Thanks L-46 for the suggestion.

 

[L.Sherm]

Also if the primer pockets need swaged do it before you neck down because mine from Rcbs won't fit in a 20 cal neck rod is to big

 

[Phasor]

Your steps look good. And the other's suggestions are good ones too. When I was doing this I found that if I annealed the cases before I started the forming I never lost one case in the process. And since you are using a Benchsource machine I believe that it would be worthwhile. I use the same Benchsource and since it does such a good job quickly I do it everytime now.

 

[BaconFat]

I was wondering about annealing the cases to start with. Since this kind of a special situation wouldn't you want to anneal lower on the case in the area that's being necked down and where the new shoulder will be.

 

[L-46]

Anneal only two cases to start,
pushing the shoulder back down the case, can require some luck, if the brass is soft from annealing it could crush and not form.

I ended up using Skip Otto case form dies, to make similar cases, they start at the full case body diameter, and go down in small steps to 17 cal, as required.
use lots of imperial case sizing lube and find some trial/old cases to get the method working.

 

[BaconFat]

Anneal only two cases to start,
pushing the shoulder back down the case, can require some luck, if the brass is soft from annealing it could crush and not form. ....

I'm getting a little dimple in the case body just below the shoulder now. I know they'll go away once the case is fire formed. This was where I wasn't sure if annealing would help. I also have to check to see if the dimple is showing up when the case is run through the die to initially create the shoulder or when I use the 20VT die to create the 30° shoulder.