Forming 20BR - Help!!!

[trappst]

Okay folks, I'm trying to form some 20BR cases but I've got a serious issue.

First off, I don't have any other BR chambers so I bought the Redding Type S neck die set for the 20BR. Type S neck die, body die and standard seater....I also have a large assortment of bushings for this and other chamberings.

My problem is straight forward but I'm not sure where it's coming from. While necking down in steps, somewhere I'm inducing a TON of runout in the neck. When I say TON, I mean like .010" as measured on my Sinclair concentricity gauge. It's bad enough that you can see the crooked neck with the naked eye.

The decapping rod assembly looks straight. Am I not adjusting the die to leave enough space between the bushing? I thought I had about 1/16 turn but maybe I need more?

Please help me!

 

[trappst]

Thanks gunamonth,

Yes, new Lapua brass and my steps are almost identical except I use a 250 bushing for that first step as I don't have the 22br form die.

I'm gonna keep track of the neck run-out during the process to see if I'm getting a bunch at one step or if it's a progressive thing.

I may also try to widen the gap between the decap assembly and the bushing to see if that'll keep things aligned within the die.

 

[CajunBlake]

about a 1/2 dozen members over on Saubier.com own 20 BR's or 20 Dashers.

may also want to post this query on Saubier for more suggestions.

 

[Fireball]

trappst, I haven't had that problem when forming 20BR cases. My experience has been like gunamonth's in that what little runout they had after forming, fire forming straightened them out just fine. Perhaps the very first step of using a 22BR form die helped me quite a bit as it "funnels" the neck nicely on the very first, and largest, sizing step. I always use regular or forming dies as much as possible before resorting to using bushings to step down the neck.

I don't think your bushing adjustment is the problem. As long as you can hear the bushing rattle around a bit you should be fine. Redding now sells a 20 caliber carbide button kit that may help out quite a bit. I am planning on buying some of these kits as I love them in my 22s and 6s. Sinclair has them in stock last I checked.

 

[trappst]

A quick update for everyone:

I finally got a handle on my runout issues! It seemed to be a combination of factors but I did order a 22BR form/trim die and I also found I didn't have the type S neck die down far enough to take the slack out of my press/shellholder.

What I ended up doing:

Run case through 22BR form/trim die
Run case through 20BR seater w/o seating stem
Type S neck die with .235" bushing
Type S neck die with .231" bushing and button
20BR body die to iron out the neck

I do still have a little bit of rounout but I can live with it. Gotta get this brass fireformed and then it'll be off to the races!

Thanks again for everyone's input and assistance!

 

[trappst]

Another update:

I just wanted to say thanks again and share some load data. Last week, I shot 35g bergers and Benchmark up to 33.2g. which gave me 4300fps. The groups were okay but I think a slight tweak in seating depth will really show their potential.

Yesterday, I shot 40g Noslers with R-10x. Yes, the 1:12 twist pac-nor handled them just fine. I started at 28.4g and loaded rounds up to 30.2g. I only shot rounds up to 29.8g as I got some stiff bolt lift and slight ejector marks on the brass. I'm considering 29.5 as my workable max.

Groups were very good with 29.2g yielding 4050fps with single digit ES and SD. Again, a slight tweak in seating depth should really tighten things up!

I'm one happy camper!