Neck Bushings- Bullet Central vs SAC

[memilanuk]

I dont have ANY bushings that size 0.003 difference going 1 size up or down... So this may be your brass prep, annealing, age, but I dont have those issues...

Yeah... before this summer, that's what I would have said too.

As for my brass prep... I'd say it's pretty good. Good enough for F-class, anyway. See here for my earlier description of the issue.

 

[padom]

Yeah... before this summer, that's what I would have said too.

As for my brass prep... I'd say it's pretty good. Good enough for F-class, anyway. See here for my earlier description of the issue.

Ah.. BC Bushings. I thought you were talking about Redding bushings.

 

[Jdne5b]

Yeah... before this summer, that's what I would have said too.

As for my brass prep... I'd say it's pretty good. Good enough for F-class, anyway. See here for my earlier description of the issue.

What’s chamber neck diameter? Could this be a result of too much clearance?

 

[memilanuk]

Ah.. BC Bushings. I thought you were talking about Redding bushings.

Currently having the same thing with my 'old' / conventional bushings - not sure if they're Wilson or Redding. 2x fired Alpha OCD brass, annealed, 0.333 bushing... passes a 0.306 pin, almost a 0.3065. 0.332 bushing... 0.302 pin (barely). So... out come the 21st Century expander mandrel (0.3055), netting me the desired fit - actually almost a fuzz too snug - on a 0.305 pin.

What’s chamber neck diameter?

The same 0.343" chamber that I've been using for oh, 15 years or so. Fired cases come out @ 0.3415-0.342". I just haven't tried bushing *only* sizing for a very long time, so I probably never noticed it before.

 

[padom]

Currently having the same thing with my 'old' / conventional bushings - not sure if they're Wilson or Redding. 2x fired Alpha OCD brass, annealed, 0.333 bushing... passes a 0.306 pin, almost a 0.3065. 0.332 bushing... 0.302 pin (barely). So... out come the 21st Century expander mandrel (0.3055), netting me the desired fit - actually almost a fuzz too snug - on a 0.305 pin.



The same 0.343" chamber that I've been using for oh, 15 years or so. Fired cases come out @ 0.3415-0.342". I just haven't tried bushing *only* sizing for a very long time, so I probably never noticed it before.

What do you mean your .333 bushing passes a 0.306 pin? What passes a 0.306 pin? the case neckl ID after sizing??

 

[padom]

I dont size any brass with bushing only. I use bushings to size my fired necks to 0.004 under loaded neck diameter. Whatever bushing does that, thats the bushing I use. I then use my 21st century mandrels to open the neck up to my final desired neck tension.. Usually 0.002... This produces extremely straight and concentric rounds.

 

[Jdne5b]

Currently having the same thing with my 'old' / conventional bushings - not sure if they're Wilson or Redding. 2x fired Alpha OCD brass, annealed, 0.333 bushing... passes a 0.306 pin, almost a 0.3065. 0.332 bushing... 0.302 pin (barely). So... out come the 21st Century expander mandrel (0.3055), netting me the desired fit - actually almost a fuzz too snug - on a 0.305 pin.



The same 0.343" chamber that I've been using for oh, 15 years or so. Fired cases come out @ 0.3415-0.342". I just haven't tried bushing *only* sizing for a very long time, so I probably never noticed it before.

What if you try a .334/5 bushing then a .332? See what the neck comes out there?

I’m guessing this situation didn’t exist with Lapua? Maybe it’s an Alpha feature?

Sizing down a bunch in one step has been noted to cause wonky issues, just thinking along those lines.

 

[memilanuk]

What passes a 0.306 pin? the case neckl ID after sizing??

Yes.

 

[padom]

What if you try a .334/5 bushing then a .332? See what the neck comes out there?

I’m guessing this situation didn’t exist with Lapua? Maybe it’s an Alpha feature?

Sizing down a bunch in one step has been noted to cause wonky issues, just thinking along those lines.

I definitely don't have this issue with Lapua. Also, I just pin gauged a handful of my Redding TiN and SAC bushings. They passed the pin size noted on the bushing...

Also, unless you have a HUGE neck, you shouldn't need to step down bushing sizing when simply sizing fired brass.

I like 0.002 - 0.0025 per side clearance in my match chambers so my necks are only expanding 0.004 - 0.007 when fired.

 

[Jdne5b]

I definitely don't have this issue with Lapua. Also, I just pin gauged a handful of my Redding TiN and SAC bushings. They passed the pin size noted on the bushing...

Also, unless you have a HUGE neck, you shouldn't need to step down bushing sizing when simply sizing fired brass.

I like 0.002 - 0.0025 per side clearance in my match chambers so my necks are only expanding 0.004 - 0.007 when fired.

He’s got about .009 over loaded round.

 

[memilanuk]

He’s got about .009 over loaded round.

Standard 308 Win 'match' neck for the 2013+ US FTR reamer, and before that, the '95 Palma chamber.

I will say that the Alpha OCD brass is a tiny bit thinner in the neck - 13 thou turned to 90+% cleanup, vs 14 for Lapua. Lapua tended to run ~14.5-ish un-turned.

Hard to believe I'm right on the edge of (or just past) some magical threshold where the sizing doesn't work as expected / advertised.

 

[L.Sherm]

. I also have a set of .001 gage pins, but like prior comments stated, they only measure the minimum of the hole diameter, and to an accuracy of .001.

The Deltronic pins accuracy are down to .0001 and the Vermont ZZ are .0002.
Deltronic makes pins down to .0001 also

 

[powderbrake]

The Deltronic pins accuracy are down to .0001 and the Vermont ZZ are .0002.
Deltronic makes pins down to .0001 also

I agree the pins are accurate to the 4th decimal point, but if you have a set of pins in .001 increments and you try one in the bushing and it doesn't fit, then the next smaller pin fits, so you can only measure to within .001 with a .001 increment pin set.

You would need a set of pins which increment in .0001 increments to measure the hole more accurately.

 

[L.Sherm]

You would need a set of pins which increment in .0001 increments to measure the hole more accurately.

Thats what I'm saying you can get pins from Deltronic down to the .0001