Brass Neck Thickness Question

[WB300]

Folks,

I worked up a great load in my .300WM using Hornady brass, 190 grain SMK, 69.0 grains of H4831, Fed mag primer, seated 3.44" OAL (just off lands). Shoots bug holes. I'm not sure how many more firings I can get out of these as the primer pockets are getting real easy to seat primers by hand with barely any tension. I purchased Winchester new brass and tried it. Bugholes opened up to just over MOA. I tried tweeking the powder charge by plus and minus .1 .2 and .3 grains to make up for the different capacity, as well as seating depth. No dice. My last guess is neck tension due to thickness of the different brass. I use standard RCBS F/L die and barely bump the shoulder back. I am not able to get a precise measurement with the dial caliper as say a digital caliper, so I cannot measure the difference in the thickness of the neck walls between Hornady and Winchester brass. Rather than work up a load from scratch again, I'm trying to save bullets and powder. And I don't want to purchase neck dies if I don't have to (I like to keep things simple). Does anyone know which brass (Rem, Norma, Nosler, Fed...etc) has the closest capacity and thickness as Hornady brass?

Or am I looking in the wrong direction?

Bill

 

[ZiaHunter]

Using a standard FL sizing die will yield different neck tensions between brands of brass. I would recommend getting a Type S FL sizing die in lieu of the neck sizing die. You can change the bushing sizes to obtain the same neck tension on brass with different neck wall thicknesses. To accurately measure neck wall thickness you will need a tube micrometer. This will also be helpful in culling brass that has large variations in neck wall thickness (>.001). For my 300 WM I have had good results with Norma brass. I fully prep all my new brass including turning the necks to obtain a uniform neck thickness. This will not only give you consistent neck tension but will generally reduce runout as well. I would recommend not using the expander ball with the die since it is not necessary when using bushings.

 

[lightman]

It sounds like you are at the point that you need to buy the tools necessary to measure either the neck wall thickness or the diameter of the neck with a bullet seated. To measure neck wall thickness, you would need a tubing or ball micrometer. To measure the neck diameter, you would need a caliper. The caliper would tell you what you need to know, and would have other uses. The tubing mic is only good for measuring neck wall thickness.It would be your choice between the dial type or digital. Both have their good and weak points.

Back to your problem; I would measure case capacity of some liquid for comparison. I use alcohol, other than water. Neck tension/clearance could be the difference, but I would look at other things first. Hope you find the answer, and please let us know.

Back to your question; I would guess Winchester or Norma brass to be close to your Hornady brass. Thats only my guess. Lightman

 

[oldfatguy]

Z Hunter and Lightman have it right about the tools. The differences in case neck thickness isn't just brand to brand, but case to case within a single lot.

You could "poke and hope" with small charge adjustments or go straight to doing an OCW work up and save powder and bullets in the long run.

OFG

 

[WB300]

Thanks for the replies gents. I'm still new to reloading. This long range accuracy thing gets involved and addicting real fast.

OFG - I like your advice. I will OCW with new Win brass once the weather starts to cool. For now I will use the short term to get the hunting rifles ready and continue to read/learn in the direction that ZH and Lightman recommended.

Bill