Need Advice on Using Expander Mandrels

[jraulsten]

Just to try something different, I have decided to give this mandrel thing a go. I've always been pleased with the results from using Redding Type S Match full sizing dies with neck bushings and carbide expander buttons, but want to see if removing the expander and using a mandrel instead will have any effect on ES and SD.

I'm looking at the 21st Century die with the window and their caliber specific mandrels. I'm not ready to go all out on the mandrel kits so where should I start? How far do you size down with a bushing and then what size mandrel would you run through to get around .002 neck tension? Say I'm sizing ADG brass for a 7 SS, would a .283 mandrel give me the desired tension with spring back?

 

[billcaldwell]

tag

 

[FEENIX]

Just to try something different, I have decided to give this mandrel thing a go. I've always been pleased with the results from using Redding Type S Match full sizing dies with neck bushings and carbide expander buttons, but want to see if removing the expander and using a mandrel instead will have any effect on ES and SD.

I'm looking at the 21st Century die with the window and their caliber specific mandrels. I'm not ready to go all out on the mandrel kits so where should I start? How far do you size down with a bushing and then what size mandrel would you run through to get around .002 neck tension? Say I'm sizing ADG brass for a 7 SS, would a .283 mandrel give me the desired tension with spring back?

I have both the window and closed version.

"I" would go with .282".

 

[SealT5]

Your going to get a lot of advice on this subject. Here's what works for me on my hunting and general purpose rifles

I FL size my brass with the appropriate bushing to give my brass .003-.005" of "neck tension". Then I use a mandrel sized .001" smaller than my bullet diameter and go from there

 

[WapitiBob]

Why not use the neck bushing and no expander at all?

 

[jasonco]

Anything other than Benchrest, you're overthinking and overestimating actual results, as far as long range hunting is concerned.

 

[SealT5]

Anything other than Benchrest, you're overthinking and overestimating actual results, as far as long range hunting is concerned.

This guy is probably right if all other variables aren't in check or this isn't for a custom rifle. I'll be the first one to admit my hunting rifles shoot way better than they need too. But then again they are custom barreled rifles

 

[jraulsten]

All my guns I load for are custom and used for hunting or PRS. It would be pretty hard to get them to shoot any better (all are .2-.3 if I do my part). I'm just extremely anal and looking for something different to do now that I'm retired again Guess it's the old Navy engineer syndrome.......

 

[SealT5]

Then I'm back on your team! Go ahead and jump on the arbor press train if you already haven't

 

[sedancowboy]

Funny how some are trying to talk him out of using mandrels. That was not the question.
For .002 interference you would use a .002 smaller mandrel spring back will be minimal.
I will say that it did lower my SDs. It also helps with trimming or the lack there of. If you are shooting in the .2-.3 range I really don't have any advice for you.

 

[dok7mm]

I have tried both the bushings and the mandrels over the years and have moved toward using mandrels on all my rifles.

I turn all my necks and anneal every firing, so that has an effect on why I use the mandrels. Consistent spring back / tension is our goal and there is a difference here between the bushing vs mandrel.

Using a mandrel, the spring back is to the inside, whereas the spring back is to the outside with the bushing. Neck irregularities are pushed outside with the mandrel and inside with the bushing. Not much difference either way with turned necks, but with irregular neck thickness, mandrels give a more concentric ID and therefore a more consistent tension.

 

[jraulsten]

I have tried both the bushings and the mandrels over the years and have moved toward using mandrels on all my rifles.

I turn all my necks and anneal every firing, so that has an effect on why I use the mandrels. Consistent spring back / tension is our goal and there is a difference here between the bushing vs mandrel.

Using a mandrel, the spring back is to the inside, whereas the spring back is to the outside with the bushing. Neck irregularities are pushed outside with the mandrel and inside with the bushing. Not much difference either way with turned necks, but with irregular neck thickness, mandrels give a more concentric ID and therefore a more consistent tension.

I anneal after every firing but do not neck turn. I'm really looking forward to trying the mandrel route. Just makes sense to me that the most consistent interference fit would come from using a mandrel if you don't neck turn.

 

[ShtrRdy]

What sort of lube do you use before the mandrel?

 

[SealT5]

What sort of lube do you use before the mandrel?

Imperial dry neck lube