Bullet Diameter-Determing Bushing Size

[7 num num]

I have a 308 with a 334 tight neck. I use a 332 redding neck bushing in a foster die. This works in loading 155 serria match with a bullet outside diameter of 308. Now Berger 155 flat base match will slip right through a sized case? I miked the bullets and found the bergers to be one to 3/4 of a thou smaller. This being said I have to use a 331 bushing to give me one more thou of neck tension then the bullets will hold again with 2 thou of neck tension.

Has any one else ever experienced this before? Or is this a bad lot of bergers. It is kind of a pain but that seems to be what a tight neck is all about.

7

 

[CyaN1de]

Maybe they went to new dies since your last batch. As the dies wear, the bullets will get larger.

 

[rcan]

I've had a similar experience as well. Good thing I got a few bushings both up and down a 0.001 when I purchased the die. Yes a pain. Watch if you change brands of brass(different neck thickness) too. I ended up sticking with the Berger's.

 

[bearhunter]

X2 rcan. It's always a good idea to have at least 3 bushings. +.001 - .000 - -.001

I haven't had problems with Berger's but I have had trouble with custom swaged bullets. Another thing, they will shoot to different points of impact. I've also had over size bullets and they just open up the groups.

 

[b72471]

Tight neck chamber

If .334 is what you want, I would drop down to a .331 bushing for a nice neck tension. In the real world you can drop down .002 for your smaller bushing .329.
Enjoy. Bill

 

[Ron AKA]

I don't reload 30 cal, so I may be missing something. Your bushing size seems too close to the neck ID.

But, bullet manufacturers do vary in how they make bullets. You don't mention what the bullets measure, but I find Bergers are around 1/4 - 1/2 thou under the nominal caliber in the body. However, the pressure ring will typically be a couple of tenths over the nominal.

Standard practice is to load 10 rounds or more in a well sized down neck, and then measure the OD of the brass where the pressure ring is located. The right bushing should be 0.002" less than that number.

The other issue is the Redding bushings. I use Forster bushings and find they are quite accurate. However, I've seen quite a few reports that Redding bushings are not sized the same as they are stamped. One quick check is to measure a sized neck. Unless it has been sized down a huge amount, the bushing is likely to be 0.001" larger than the measured sized neck. So, I would check to see if the bushings are really what they are stamped to be.