45 undersized die

[CQB45ACP]

I’m thinking the goal of understanding the benefits of the undersized die is two fold, Bullet Retention & Setback Resistantance, both improved.
Let me know if that’s not the intention.

Yes

 

[CQB45ACP]

I’m thinking the goal of understanding the benefits of the undersized die is two fold, Bullet Retention & Setback Resistantance, both improved.
Let me know if that’s not the intention.

Okay

Looks like .4635-.464 for the U and
.4655 for two different standard dies

With no warranty expressed nor implied.

I was surprised how difficult that was

 

[JHTexas]

Thanks for taking the time to measure the dies.
What expander did you use with the last loads that you tested?

When I get a good copy of the “U” die I’ll do some testing and we can go from there.

 

[CQB45ACP]

Thanks for taking the time to measure the dies.
What expander did you use with the last loads that you tested?

When I get a good copy of the “U” die I’ll do some testing and we can go from there.

None. No expanding.

 

[JHTexas]

Yes, thanks for reminding me. Old age I guess…

 

[JCSC]

Just adding results to close this out.

I used the U die and factory rcbs expander.

I noticed slightly different sizing pressure, but really no felt changes to the expanding or seating operations.

Prior non U test yielded up to .010” set back on a dummy round.

With U die and 200 gr Xtreme FP I had about .001” setback per cycling. .004” total after 5 chamberings.

I will continue and see no reason not to implement this in my process.

 

[CQB45ACP]

Just adding results to close this out.

I used the U die and factory rcbs expander.

I noticed slightly different sizing pressure, but really no felt changes to the expanding or seating operations.

Prior non U test yielded up to .010” set back on a dummy round.

With U die and 200 gr Xtreme FP I had about .001” setback per cycling. .004” total after 5 chamberings.

I will continue and see no reason not to implement this in my process.

Happy you’re happy

A couple of us are still churning away on this in our own little world—post #75 describing what we’re doing.

At present I’m undersizing and not expanding except for coated bullets when I standard and expand.