Slow Burning vs Fast Burning

[dsbw]

This issue tickles me no end, particularly since there seems to be divided expert opinion on the matter. My question is, which propellant is best for barrel life, slower burning, with lower temperature but a flame that's burning longer, or faster burning, higher temperature, but with quicker burning flame?

Also, with the quicker burning propellant you usually use three to four grain less charge than with the slower powder??

I need some expert guidance please?

David

 

[scout1]

dsbw,

this fence divides a lot of shooters with some perched right on top. I make my selections based on what shoots best for the cartridge / bullet combination. Purchasing Q.L. and actually being able to look at the pressure curves has influenced my recient selections of slower powders than what I have used in the past without giving up the performance I desired. If an active competative shooter is worried about throat and barrel wear, they shouldnt be. There are a number of cartridges out there that are competitive and will go 2500 rounds or more.

 

[Rust]

I base powder choices on what works best over the chrono,ES/SD is critical at long range) and what the target looks like.

Generally I've found that a little faster powder compared to the slowest appropriate for a goven chambering works best for me. For instance H4350 vice H4831 or RL-22 in 6.5 X 284. There is a caveat here though, as I use a 26' barrel instead of the 30' tubes preferred by most folks. I suspect that the H4350 gives a better burn in the shorter barrel, has a lower pressure at the muzzle which may produce less bullet upset upon exit. My theory at any rate. I've had the similar results with other rifles ranging from .223 to .338 RUM.

So my best advice is find out what works best in the rifle you have. When looking for optimum accuracy at 1,000 things like barrel life don't enter the equation. Doesn't matter if the barrel will last a few extra rounds if it isn't accurate enough to win a match.

 

[CJ6]

I like full cases so I tend to run the slower powders.I look at it this way if you run a faster powder and have air space in the case you need a smaller case JMHO .But I still let the rifle tell me what it likes......,anyone else run H-870 or H-5010 in a 6-284 besides me) ?

 

[TonyR]

David
Here is aa accurate barrel life formula that may help show the tradeoff among a number of factors. It seems to give reasonable results for many cartridges such as the 6mm BR and 6.5X284 and other cartridges where I have some experience.

http://www.websitetoolbox.com/tool/view/mb/file?username=6mmbr&id=719406

I use pressure estimates from QuickLoad

There do appear to be some cartridges were it doesn't work such as the 30BR discussed in this thread.

http://www.websitetoolbox.com/tool/post/6mmbr/vpost?id=3218460

Still, you might enjoy playing around with it.

 

[dsbw]

Geez, thanks guys, quite a lot of useful replies. I agree with the points on barrel life v accuracy, but it obviously depends on HOW fast your barrel is wearing with a particular propellant.

Tony, tx for the spreadsheet, works a charm man!! One interesting observation, your calculation shows a significant increase in barrel life if you choose moly over naked bullets? I am asking, because I don't know, does it really make such a difference in barrel life?

David

 

[TonyR]

David.
I haven't had any experience with moly coating so I don't know whether it helps barrel life or not. I have seen the topic discussed on this site so you could try the search function for this site.