barrel length and burn rate

[TheDeicide]

I have read a ton of posts and all I've learned is shorter = faster and longer = slower. Can anyone point me at some good articles or videos on the subject. I am tempted to buy QuickLoad but I don't really wanna spend $150 on it.


Edit: Sorry I wasn't as clear as I should have been. A shorter barrel is better with faster powder and a longer barrel is better with a slower powder. I also picked up that the smaller caliber in the same barrel (30-06 vs 6.5-06) is the smaller bore builds pressure faster because it is more restricted so it would run a slower burn rate than the larger diameter bore. All other things being equal.

 

[bigedp51]

Normally the slower powders that give you the highest velocity in a longer barrel will give the highest velocity in a short barrel. The only difference is the short barrels will have more muzzle blast.

Look in the Lyman reloading manual at rifle loads and then look at the same loads for the Contender pistol. You will see what powders provide the highest velocities. I have a 16 inch barrel on my Winchester 94 Trapper model and a 20 inch barrel on my .308 Savage. And the slower powders still give you the highest velocity.

That being said you can download any cartridge using a faster burning powder to practice with. "BUT" you will reach max pressure at lower velocities than with slower powders.

 

[entoptics]

I can't supply any more definitive sources than "a ton of posts", but my understanding is that until you get to the extremes (e.g. pistol length rifles, or rifle length pistols), there's no significant difference in behavior.

As bigedp51 states, the burn rate that gives the fastest velocity in a particular cartridge will do so regardless of barrel length. For example, if H1000 is faster than H4350 in a 26" 243 Win for a particular bullet, it will also be faster in an 18" 243 Win.

 

[Gord0]

I can't supply any more definitive sources than "a ton of posts", but my understanding is that until you get to the extremes (e.g. pistol length rifles, or rifle length pistols), there's no significant difference in behavior.

As bigedp51 states, the burn rate that gives the fastest velocity in a particular cartridge will do so regardless of barrel length. For example, if H1000 is faster than H4350 in a 26" 243 Win for a particular bullet, it will also be faster in an 18" 243 Win.

And probably faster in a 10" 243 win. Maybe if you got down to something like a 3-4" faster might help...

 

[DJ Fergus]

I have read a ton of posts and all I've learned is shorter = faster and longer = slower. Can anyone point me at some good articles or videos on the subject. I am tempted to buy QuickLoad but I don't really wanna spend $150 on it.

My personal findings May differ from other people's findings. What I have observed is sometimes slower burning powders in short barrels leaves alot more powder fouling in the barrel. I can't prove it but I have my suspicion that this speeds up carbon fouling. I have observed increased carbon build up on the muzzle face when running a muzzle brake and more build up in the muzzle brake itself vs running faster burning powders in short barrels. If you are shooting later in the evening, you will notice the muzzle flame upon firing will be more lenghty vs a faster burning powder in a shorter barrel. You get a more complete burn in a shorter barrel with faster burning powders vs something like retumbo or n570. All that being said, there are plenty of folks running slower burning powders in shorter barrels with success but bore size has influence on this also. Let the rifle tell you what it likes. But if you are trying a slow powder in a short barrel and find yourself having to clean it quite often to maintain accurracy, then you may consider stepping to a little faster burn rate.

 

[entoptics]

...If you are shooting later in the evening, you will notice the muzzle flame upon firing will be more lenghty vs a faster burning powder in a shorter barrel. You get a more complete burn in a shorter barrel with faster burning powders vs something like retumbo or n570...

I need to remake this video, now that I have an iPhone with 240 fps - 1080P capability, but I still get a kick out of it (pun intended).


I based my original comment, at least partially, on my experience with magnum handguns. I have loaded a huge variety of ammo for 357 mag, 44 mag, 454 Casull, and 475 Linebaugh in barrels ranging from 3" to 24". The slowest burning pistol powder out there (H110, Lil' Gun, 300-MP), ALWAYS proves the fastest for any barrel length.

As you go faster in burn rate and lower in case fill, speed decreases (and fireball size ). Whether it's a 3" or 18", a max load of H110 is faster than a max load of 2400, which is faster than a max load of Blue Dot, which is faster than a max load of Unique.

This holds true for rifles in my experience also. Whatever powder has the heaviest max charge, while resulting in max SAAMI pressure, will be the fastest velocity for the caliber. Of course, if the burn rate is too slow, then you can fill the case to the brim, and never reach max SAAMI pressure.

 

[West Calamus]

I have read a ton of posts and all I've learned is shorter = faster and longer = slower. Can anyone point me at some good articles or videos on the subject. I am tempted to buy QuickLoad but I don't really wanna spend $150 on it.

HELP ME OUT,shorter what equals faster what? Longer what equals slower what? Just not sure what your saying. thx

 

[West Calamus]

sorry, didn't read the title.. got it now.

 

[DJ Fergus]

I need to remake this video, now that I have an iPhone with 240 fps - 1080P capability, but I still get a kick out of it (pun intended).


I based my original comment, at least partially, on my experience with magnum handguns. I have loaded a huge variety of ammo for 357 mag, 44 mag, 454 Casull, and 475 Linebaugh in barrels ranging from 3" to 24". The slowest burning pistol powder out there (H110, Lil' Gun, 300-MP), ALWAYS proves the fastest for any barrel length.

As you go faster in burn rate and lower in case fill, speed decreases (and fireball size ). Whether it's a 3" or 18", a max load of H110 is faster than a max load of 2400, which is faster than a max load of Blue Dot, which is faster than a max load of Unique.

This holds true for rifles in my experience also. Whatever powder has the heaviest max charge, while resulting in max SAAMI pressure, will be the fastest velocity for the caliber. Of course, if the burn rate is too slow, then you can fill the case to the brim, and never reach max SAAMI pressure.

I've had two rifles where I couldn't get enough powder into the case to reach max pressure. Barrels were shorter than I would have considered optimum for the cartridge. In both cases e.s. was highly irratic. At some point as I reached a threshold, velocity seemed to fall off a bit as I increased charge. If a fellow wants to try a slower burning powder in a short barrel, I see no harm in it and it might work out nicely. Tell tale signs will eventually show if indeed it's not going to work out in the long run. I just let the rifle tell me what it likes. I do know that with any type of combustion, the more complete the burn is, the less carbon is produced. All that being said, my personal powders are mostly slower burning. I start out slow and gradually go to faster one step at a time if needed: N570, retumbo, h1000, rl26 so on and so forth.

 

[Buttermilk]

I shoot a lot of short barrels. Typically, I've gotten my fastest velocities with some slower burning powders for the specific cartridges.

There are some exceptions but typically same powder that gets velocity in long barrels does the same for shorter barrels.

I've shot a lot of 14", 15", 16.5", 17.5" barrels in specialty handguns over the past 27-28 years.

 

[DJ Fergus]

I can push 80gr bullets out of my 24"bbl 25-06 faster with rl17 than I can with retumbo. With more barrel length, I do believe the retumbo would produce higher velocity with those same bullets.

 

[West Calamus]

poke me with a stick if I'm off topic! Does not slower powders generate more velocity in longer powder column's (i.e. 30-06 step child cartridges vs. 308 or 6.5 creed based length cartridges) then faster burning powders? The longer powder column's require more time to burn to build up pressure. Inversely a shorter powder column (308 or creedmoore) needs a faster burning powder in a shorter case to build pressure. Does not the % fill of the case also influence the most desired burn rate? Please don't be to harsh on my ignorance.

 

[DJ Fergus]

Another example I have is in a 22 creedmoor that I loaded for. H4350 would run just as fast as h1000. Now the question is, if the barrel was longer would the h1000 been faster? I think it's a possibility. Don't get me wrong, I love slow burning powders, but there are some situations where they work better than others. I'm not trying to prove anyone wrong one way or the other but just implying that every situation is different and never rule out anything without trying it first.

 

[josip89]

In my case ,some old 3006 that have 65cm (nearly 26") barrel and 200gr Gamekink have max velocity with n560 (cant remeber what velocity).
Then we chop barrel to 50cm or (little bit under 20") and still have more velocity than the faster powder.

What I dont know is what happen if we put 150gr or 130gr bullet on the same test with same powder.