Why does the 30BR like heavy neck tension?

J

josh shrum

New member
Off work with a hurt back and bored, which generally gets me thinkin' (as there is little else for me to do).

Why does the 30BR like neck tension?

Is it because we are usually crushing powder and the heavy neck tension prevent seating depth changes as powder pushes back?

If the answer is obvious/already well known please forgive me, still a relative newbie.
 
Josh, my belief is that the neck tension makes H4198 'act' like it's a bit faster.

Good shootin'. -Al
 
I like to think of the barrel as a part of the chamber and tighter neck tension holds the bullet in the chamber a bit longer and the bullet exits as the energy of the ignited powder is spent. I think.
 
so why not just jam ? more energy to engrave a bullet than unseat it ?
too much ??
and does this apply to lt30 also ??
 
rsmithsr said:
so why not just jam ?
Click to expand...

My standard starting recipe for the 30BR (in fact....every .30 cal. case for Benchrest I've worked with) is:

- A neck bushing .004 smaller than the neck measures with a bullet seated.
- The seater stem adjusted .020 longer than when the rifling marks just disappear.

Tune it with the powder charge from there. When it shoots small, keep the powder charge where it is and back the seating depth up until it shoots bigger. Readjust the seating depth and then tinker with the neck bushing.

As we say in 'Forbidden Zone' triple negative speak: "It doesn't never not work." :eek:
 
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thanks al
Al Nyhus said:
My standard starting recipe for the 30BR (in fact....every .30 cal. case for Benchrest I've worked with) is:

- A neck bushing .004 smaller than the neck measures with a bullet seated.
- The seater stem adjusted .020 longer that when the rifling marks just disappear.

Tune it with the powder charge from there. When it shoots small, keep the powder charge where it is and back the seating depth up until it shoots bigger. Readjust the seating depth and then tinker with the neck bushing.

As we say in 'Forbidden Zone' triple negative speak: "It doesn't never not work." :eek:
Click to expand...
 
Problem is

how many dollar cartridges and barrels does on want to burn up learning. Back in the day when components and barrels were not such an issue,one could or did burn them without a second thought but now we don't know if we will have components again and if we do, at what price? Rumor has it that a critical ingredient in powder has gone up by 1000 percent. 30 Cal bullets use to be 28 cents and primers a little over a buck per hundred. Brass hasn't gone up as much as the other things, I don't think. The Great Unknown!

Pete
 
glp said:
Al, you ever try N120 in the 30BR?
Click to expand...

Hi Greg. In my work with N120 in the 30BR, it wasn't quite as edgy as H4227...gave a little bigger cushion before things got herky. I blended some with N130 hoping to open the window a bit wider. By the time it calmed the N120 traits down, it was a 85/15 blend.

Ditto the H4227/H4198 blending. The H4227 characteristics overshadowed the H4198 until it got around 85/15.

Randy Robinett had some French powder that we called 'Le Poudre Magique' (The Magic Powder) :cool: that worked well.

I do believe Randy could throw salt peter, ground up charcoal briquettes and some old celluloid 8MM home movie film together and make it shoot. ;)

Hope you and yours are staying health. -Al
 
Al,

I shot some N120 this past summer, 27 grains, just to see how it went. Was accurate but velocity was lower than I expected. I need to carefully try it again in 2021.

I agree with you wholeheartedly about Randy and his capability to make lots of things work. He sent me some pics of his mule deer hunt, 3 to be exact. One of his son, one of a hunting buddy and one of Santa Clause. It took me a bit to realize that was him hiding under the snow white whiskers! I reminded him of what can live in that facial jungle. He allowed he was not concerned...tough hombre that RGR!!
 
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