Bushing die giving inconsistent sizes

[Southern shooter 59]

.308 Palma brass, trimmed and turned. Annealed after every firing. Redding full length bushing die. Diameter of the case neck of a loaded round is .334. I was using a .328 bushing in the die. I was having more vertical than I should so I started searching to find the reason. After sizing a case the dimension will be .003 to .005 less than the bushing size. If I change the bushing to a .330 the case is .329 consistently. I have measured the bushings and they are accurate. This results in inconsistent neck tension and therefore affects vertical especially at LR. Any tips would be helpful. The excessive movement of the brass also affects concentricity.

 

[Sheldon N]

Try sizing in stepped levels with multiple bushings so you're not making that big of a sizing jump all at once. This article from Redding talks a bit about it in the later paragraphs.

http://www.redding-reloading.com/tech-line-a-tips-faqs/140-bushing-selection

 

[Willie]

Good call Sheldon! If you reduce neck too much in one pass, it'll be smaller with more variance every time. Learned that with son's factory chamber.

 

[Ringostar]

Just curious, if a loaded round is .334. Why are you sizing down .006 from there?

 

[BoydAllen]

This may sound a little radical, but I assure you it is not. Try using an expander die and mandrel on your case necks after the FL/bushing die. I think that it will solve your problem. Also, something else that you will probably reject because it sounds unconventional is to use your Fl die as a body die after sizing necks with a Lee collet die. If your flash holes are small you may have to modify the decapping stem. I was working with a fellow who has a custom top of the line .308 and he saw better results using the Lee/body combo than with his Redding FL and the bushing. Remember the definition of insanity ;-)

 

[Willie]

This may sound a little radical, but I assure you it is not. Try using an expander die and mandrel on your case necks after the FL/bushing die. I think that it will solve your problem. Also, something else that you will probably reject because it sounds unconventional is to use your Fl die as a body die after sizing necks with a Lee collet die. If your flash holes are small you may have to modify the decapping stem. I was working with a fellow who has a custom top of the line .308 and he saw better results using the Lee/body combo than with his Redding FL and the bushing. Remember the definition of insanity ;-)

That is an excellent idea from Boyd, I failed to mention that in my post above. About three years ago, I started setting my final I.D. with a mandrel, as I use bushing dies. Tried it with one rifle and my results were so good that it is my final step, prior to charging and seating for all rifles. No longer a radical suggestion.

I also wonder why the OP is sizing his neck's so much smaller than loaded neck. ????

 

[tenring]

I recently had a similar problem with 30BR brass. My Harrels die with steel bushings in it, was not firmly seating bullets, and they would slide out with very little effort. I tried four different pieces of brass and different steel bushing used with each one. Measured OD on each was way off the stamped bushing size - did not matter whether Redding or Wilson bushing. Solved the problem with a titanium .323 bushing. Measured neck OD with it was right on and no more loose bullet problem,. Titanium bushings are worth the price!

 

[Southern shooter 59]

Thanks for the information. Is the mandrel you are using the .002" under sized? How much will I need to tweak the powder to compensate for the reduced neck tension. This load is less than 1/2" moa if neck tension is consistent. To answer the question about why .006" under, another load for this rifle shoots good there. So I started there with this load.

 

[BoydAllen]

On the neck tension, was the load that shot well with it with the same powder? The reason that I ask is that some powders apparently like a lot and others like a little. (neck tension)

On bushings, the most dimensionally accurate that I have seen, by far, have been carbide. They are ground rather than turned to size.

 

['Freak]

What’s wrong with using the .330 bushing resulting in a consistent .329” sized neck OD? That’s still .005” under loaded neck diameter, a plenty if not more than enough.

 

[Southern shooter 59]

Same powder, both loads and both bullets.

 

[Southern shooter 59]

I agree with less neck tension. I will use the .330 and a .331 and see how it shoots. I will try my collett die as well. If accuracy suffers I will start bumping the powder up till accuracy returns.
Thanks to all.

 

[savageshooter86]

What is this rifle for? That seems like a lot of tension for 308. I also had same issue because sizing that big of step at once caused issues. On my other rifle that only sizes down 1k my sized necks are spot on. Have to match your loaded round to the bushing size. Starts with what you neck turn to and use caliber to estimate loaded round to select proper set up to avoid over sizing

 

[Southern shooter 59]

I use the rifle for FTR MR and LR. I was advised by a much more experienced shooter to try more neck tension. I am relatively new to this level of reloading, therefore I am still learning.

 

[Southern shooter 59]

thanks Joe, I have the tools, from the answers on here I should be able to combine a full size die with a collett die that leaves the inside diameter .3045 and an expander ball .306 and arrive at a properly tensioned case neck. So then, I will load up sets of bullets with ascending powder charges starting from where I was until the vertical is least, and the ES is smallest. If I am missing something, let me know.

 

[Southern shooter 59]

Did some experiments and here are the results;
1. FL size use a body die
2. Lee collett die- interior neck diameter 0.3045
3. Expander ball diameter after spring back 0.306
I checked concentricity after each step, end result is a sized case ready for bullet seating with .0005 eccentricity.
Thanks again.