PRS Talk neck size 6 creedmoor alpha brass Breger 105 hybrid

[SirShagalott]

Probably a long shot, but hoping someone has a neck dimension of a loaded round using the following:
6 Creedmoor
Alpha Brass
105 Beger Hybrid

I am needing to order a bushing and being the idiot that I am, I have shot all by loaded rounds before thinking about it...Thanks in advance for your help!

-Ric

 

[ToddKS]

I believe .267 would be a safe guess on bushing size. That is what I am running on my 6GT with Alpha brass.

 

[SirShagalott]

I believe .267 would be a safe guess on bushing size. That is what I am running on my 6GT with Alpha brass.

Thank you Todd!

 

[Hickswr]

I’m using a .266 in the same setup. Get between 0.002 and .003 neck tension.

 

[SirShagalott]

I’m using a .266 in the same setup. Get between 0.002 and .003 neck tension.

Super helpful...thank you!

Are you using the Short Action Custom bushings by chance?

 

[Lawnboi]

I can measure when I get home but if I remember correct.

Amp annealed
SAC modular sizing die. .266 bushing
.241 expander/decapper

.0025 interference.

 

[Lawnboi]

This is 5 times loaded now.

 

[DeathBeforeDismount]

You need to measure your brass neck thickness. The loaded diameter doesn't really matter because it doesn't account for neck tension. Brass from same manufactures in different lots can have different thicknesses. So you always need to measure your brass to get the correct neck thickness.

Take 5 random fired cases. Take an average of the Measured neck thickness and do the following:

Bullet diameter + (2 x Neck thickness) - .003 = Bushing size.

So if your shooting a .243 bullet and your neck thickness is .013, you would use .266 bushing.

That will give you about .002-.003 of neck tension with some spring back accounted for.

You also probably want to use a mandrel to open up the case mouth uniformly after sizing. Mandrel / sizing bushing work together to get desired neck tension without overworking your brass and keeping everything uniform and concentric.