6 Dasher - Expander Mandrel 101

[lazyMlazyK]

The 6 Dasher I've been working on is getting close to being finished again, and I'm wondering if I should use an expander mandrel on my virgin Alpha OCD brass. There are a couple of case mouths that are slightly dented, and I don't care to use the expander ball on the Redding bushing die.

The barrel was reamed with Alpha's legacy reamer. If I'm using Alpha brass, what size expander should I get? I've never used an expander mandrel so this is all new to me. Do you typically only use the expander mandrel on virgin brass, or do you undersized with a bushing, then expand back out with a mandrel to set your neck tension? I plan on only using a bushing to set neck tension after firing, but am open to opinions!

Thanks for any info!

 

[762plinker]

i would size down and then expand up

 

[NZ_Fclass]

I find that with annealed 6BR Norma brass, a .243 mandrel works for me. But for you, it will dependent on the brass thickness, the sizing die, the neck tension that your want, neck dimension of the chamber... but once I started using a mandrel for all the calbres that I shoot - It has been another rabbit hole to dive down - I can see an improvement on load quality and a change in the way I reload ammo.

 

[mikea5232]

I just got a dasher with a .272 neck and using alpha brass. Loaded rounds measure .269. I expanded the virgin necks with a. 242 eplander and shot a few groups this morning. Tomorrow if it's not snowing I'm going to shoot groups with and without too compare. But the bullets seated harder than i prefer without expanding.

 

[Ray123]

I just got a dasher with a .272 neck and using alpha brass. Loaded rounds measure .269. I expanded the virgin necks with a. 242 eplander and shot a few groups this morning. Tomorrow if it's not snowing I'm going to shoot groups with and without too compare. But the bullets seated harder than i prefer without expanding.

I use the exact same combination .272 neck, alpha brass, .242" expander ...loaded round .269" Remington 7 1/2 primer, Varget or RL 15, 108 gr Berger, with RL 15 maybe having a slight accuracy edge.
Wanna go fast try 6.5 Stabal with the 107, 108, 110, to 115 gr. I like the 110 gr SMK at 3085 fps in the windy days on steel. Try H4895 for some slow accuracy loads with 115 gr. Even IMR 4064 was pretty decent.
CFE 223 for 58 grs Vmax Varmint loads fast and accurate in 7.5 twist.
I find the 6 Dasher easy to load for, accutate, easy to shoot, and just a lot of fun...

 

[Sightcast-Alan]

How much spring back are y’all seeing with a .242 expander on new or anealed cases ?

 

[Rset]

The 6 Dasher I've been working on is getting close to being finished again, and I'm wondering if I should use an expander mandrel on my virgin Alpha OCD brass. There are a couple of case mouths that are slightly dented, and I don't care to use the expander ball on the Redding bushing die.

The barrel was reamed with Alpha's legacy reamer. If I'm using Alpha brass, what size expander should I get? I've never used an expander mandrel so this is all new to me. Do you typically only use the expander mandrel on virgin brass, or do you undersized with a bushing, then expand back out with a mandrel to set your neck tension? I plan on only using a bushing to set neck tension after firing, but am open to opinions!

Thanks for any info!

An mandrel is just another way to set neck tension. I no longer use them and now set my neck tension with bushings. I do not use expander balls in any of my dies. Either way works. I didn't see any advantage on the target so I eliminated the extra step from my process.
Doesn't matter if you use a bushing or a mandrel, you are going to have to know how much neck tension your rifle and your load likes. This has for me, always necessitated the need for multiple sizes of either so I could test it.
Your chamber doesn't care which you use. Seating your bullet determines the final neck OD, not the method of sizing the neck and setting the tension.
As for the couple of dented case mouths.. Well, the method for straightening those will depend on your ultimate choice of the above processes.