Short barrels powder choices

[Bobcat 33]

Just have to ask a dumb question. Many has seen me here as a new member posting about my experience with my new 6.5 PRC asking many questions and getting some great helpful answers. My PRC is 20", im 65 and been loading since late 80's and trying to figure this out. Everything powder wise for this short barrel has been slow burning powders. In my early years the slowest i ever used was imr 4831 then in 09 building a 338 edge got introduced to H-1000. I could accept that since i was using a 28" barrel. So why the slow burning in a short barrel? What would happen using say IMR or H 4350, H-414 jsut wondering why a slow burner in this 20". For some reason i would of thought a fast burn in a short barrel. Why is my thinking wrong?

 

[hereinaz]

The powder speed is most relevant to the initial pressure curve to get the bullet moving.

Fast burning powder create pressure fast behind bigger bullets and in larger magnum charges, so you can’t get the speed. Slow burning powders burn too slow and the pressure is enough to start the bullet but it moves faster than the powder can build pressure.

Most speed is from getting maximum pressure popping the bullet into the lands and moving. Longer barrel length isn’t nearly as big a factor.

What makes a good powder won’t be determined by barrel length as I understand it.

So, a faster burning powder isn’t “better” in a short barrel based on the premise of getting a “complete burn” in the barrel.

 

[Snowwolfe]

Only way to know for sure is to chrono the loads you shoot. Until then, everything else is just a guess. And the guesses are usually wrong.

 

[Bobcat 33]

Only way to know for sure is to chrono the loads you shoot. Until then, everything else is just a guess. And the guesses are usually wrong.

I chronograph every shot I take anymore thanks to my new garmin. It’s so way to take to and set up at range vs the others

 

[112Savage]

Pull out the sierra loading book. Go to the rifles section for any cartridge. Let’s pick 243 Winchester. Then go to the single shot pistols section. In the same weight bullets, the fastest loads will be similar powders.

Truly the only reasons not to use the most optimized powder for a given cartridge regardless of barrel length are:
Inaccuracy with that powder
Inconsistency with that powder
Attempting to decrease muzzle pressure
Attempting to decrease muzzle flash

 

[wind gypsy]

Pull out the sierra loading book. Go to the rifles section for any cartridge. Let’s pick 243 Winchester. Then go to the single shot pistols section. In the same weight bullets, the fastest loads will be similar powders.

Truly the only reasons not to use the most optimized powder for a given cartridge regardless of barrel length are:
Inaccuracy with that powder
Inconsistency with that powder
Attempting to decrease muzzle pressure
Attempting to decrease muzzle flash

But Gordon's Reloading Tool told me i'm not getting 100% powder burn! /sarcasm

 

[SloppyJ]

% burn is about the last thing that I care about if the rest of the load is working fine and is consistent. Try N560 in your 6.5prc if you're worried about it which will be similar to 4831sc.

 

[hereinaz]

Just listened to an interesting Hornady podcast going way deeper than anyone but a nerd needs to know about pressure, velocity, powder burn, effecting primers on velocity at .5 to 1%, etc…

I found it interesting but it won’t really change anything I do.

 

[TaperPin]

The only time I ever questioned burn rate was a lot of Weatherby factory ammo loaded with a super slow powder that produced a one foot flame. I remember it as a two foot flame, but that just can’t be right, so let’s just call it one nice bright foot of pure American Freedom. An eagle was born every time that ammo was shot. *chuckle*

 

[AMG04]

I shoot almost exclusively 16 and 18" barrels with a suppressor.

Quickload is a nice tool to help analyze suitable powders. Case fill, pressure and results down range are a few metrics more important to me than 100% burn.

Now a case full of H1000 in a 16" 300 SAUM makes a nice fireball... Increase burn rate to H4350, H100v to about H4831sc and that's no longer an issue.

Lighter for cartridge bullets and faster powders seem to be more efficient from my short barrels and trend towards lower ES/SD numbers. Example: 123-130gr over Varget in a 6.5x47 Lapua instead of the 140 class and H4350.

If a powder is too slow and doesn't get a consistent burn in the short barrel, I see some wild ES/SDs.