Not accuracy but primary ignition.

[AJC1]

I fully understand that every barrel is its own monster. What I am curious about is primary ignition. Will a round with a good es/SD have good numbers in a different chambers or does that also move...

 

[JFrank]

Benchrest Guru’s like Alex Wheeler and Lonnie Anderson have tested this quite a bit a feel that the receiver ignitions are somewhat unique to themselves with regards to firing pin strike and drag etc. myself I always retest things like primer type and depth when changing springs or rifles.
Hunting or fun guns at shorter range may not show much decline or improvement. The key for us is to test for our selves.

 

[AJC1]

Benchrest Guru’s like Alex Wheeler and Lonnie Anderson have tested this quite a bit a feel that the receiver ignitions are somewhat unique to themselves with regards to firing pin strike and drag etc. myself I always retest things like primer type and depth when changing springs or rifles.
Hunting or fun guns at shorter range may not show much decline or improvement. The key for us is to test for our selves.

I've never owned more than one of a rifle of the same chambering before so now I have more than one 223. I figured if I had good primary ignition numbers in one 223 it would shortcut the development process a little bit. Like start here and test around.

 

[JFrank]

Easy to test the little stuff like primers and bullet hold ( neck tension) with each ignition or barrel change. It just goes with the territory.
We use a charge ladder of 2-3 rounds each to see the load come into and out of tune at the longest range we have available. That keeps components to a minimum and the results are usually pretty obvious. Chronograph info I’d handy to have as well but the target is king.

 

[FROGO207]

Remember that the chamber is only part of the equation. The barrel and its harmonics are just as important. ES/SD are a product of chamber size, barrel internal size, rifiling, smoothness, twist, and harmonics. Even if they are the same length and made one after the other. Sometimes you get lucky and they are really close but all mine are a story to themselves. I find handgun barrels are often closer in performance and feel it is due to being shorter and having less influence on the bullet as it travels through it. But that is a personal observation. There are some caliber bullet size/weight combos that are really accurate in many different firearms but that does not hold true for the majority. I will often "cheat" and try an established load in a new gun and try tweaking from there. My usual tuning method is to do a full workup find the widest accuracy node (usually the lowest) and test in the center of that trying different bullet insertion lengths/crimp or not etc. to maximize accuracy. Low ES/SD often is in the center of that accuracy node as well. I guess it depends on how accurate you need each gun to be as to the extreme you go to.

 

[Kp321]

If you can find it, look up an article about Rocky Gibbs experiments with “forward ignition“. He soldered a tube over the flash hole to carry the primer flame to the top of the powder charge. As well as I remember, he did show an accuracy improvement but it was next to impossible to reload the empty cartridges.
Rocky Gibbs was an interesting guy, better known for his family of improved cartridges based on 270 brass with the shoulder blown forward.