Hornady vs Sinclair Tools for CBTO and CBTD?

[nksmfamjp]

I'm about 25 years down the rabbit hole. I'm a Hornady supporter generally. I have been diving deep into rifle accuracy since I got the AR15 to shoot 5 shot 0.5" groups….then the 6.5x55 Ruger shooting under 1"….then getting some 0.1's out of the Savage…..6PPC, 300 Sherman….blah, blah, blah

The thing is, the stuff under 0.5" is flirting….I get there, then the 5 groups of 5 shots all blow up. So now I'm rethinking everything. I'm even trying to get into an A&D scale, etc.

So, I see about 0.001"-0.002" variation in measurement repeatability. So, I'm hoping the Sinclair tools with their greater contact area are more consistent.

 

[SealT5]

Sounds familiar!

 

[misterc01]

I use both, and compare them to each other to get more "accurate"" reading. They each give a reading that is different from the other, but I am looking for consistency in the readings on each. So if I get say a consistent .004 on the Hornady, and a consistent .006 on the Sinclair, I know I can use either when I actually measuring my reloads. So far, it works for me.

 

[skyrep]

I've been using the Forster Datum Dial Ammunition Measurement System.
Easy-to-use ammo measurement system gives you the data you need to refine your case sizing operations.
This complete kit includes one Datum Dial tool for checking cartridge cases, Both bullet/Cartridge dials for use with 17 cal, 204, 224, 243, 257, 264, 277, 284, 308, and 338 bullets, laminated chart showing common datum diameters, instructions and storage box.

 

[KSAv8r]

Somehow, I have acquired the Hornady, Sinclair and Franklin tools over the years. They will each give a slightly different reading but all are in the ballpark. Just remember, this is not an absolute number to where the ogive touches the rifling. It is a reference point that will vary even with bullets from the same lot number has been my experience. It also depends on exerting the same amount of pressure and feel, which is highly subjective. Unless you are running a custom magazine or loading each bullet in the chamber by hand, you will likely be limited by the length of your magazine for overall cartridge length. I have quit measuring max CBTO because of this reason. When starting load workup, I begin at the bullet maker's recommendation for cartridge overall length. After selecting the best powder and charge weight (or these days, whatever is available), I will then begin tuning the load by varying bullet jump in 0.005" increments until I find a node with the least dispersion. From there, I will vary the bullet jump by 0.001" to find the center of that node. This seems to work for me. However, I'm sure there are better techniques you all have discovered. Over the years I have tried to streamline the reloading process and concentrate on the items that make the most difference in producing quality hunting and benchrest ammo.

BTW.......Happy New Year!!!! May 2022 bring better availability of reloading supplies and prices somewhat returning to near normal.

 

[QuietTexan]

To big boomers, small groups, and successful hunts!