Fast vs slow burning powders for short barrel .223/5.56 loads

[brycewise]

Im new to the world of reloading. Im looking to safely get the combination of the highest velocity possible with the lowest flash signature with medium to heavy for caliber weights (60 - 75 grains) in a 10.5 inch .223/ 5.56 barrel

What are the pros and cons regarding different powder burn rates for this application?
which powders would you recommend for that application... Accurate 2200, 2230, H335...etc

 

[jmr40]

The fastest burning powders burn completely within just a few inches. The slowest burning powders in 1-2 more inches. Even the slowest powder will burn completely in any rifle barrel. When talking handguns then it might make a difference. The powder that produces the most speed from a 26" barrel will still produce the most speed from a 16" barrel. Longer barrels produce slightly more speed even though the powder was burned within the 1st few inches because the pressure continues to build behind the bullet for more time before the bullet exits the muzzle. I think you'll have to go a lot shorter than 10" for this to matter.

Generally speaking heavier bullets get more speed from slower powders. Lighter bullets more speed from faster burning powders regardless of barrel length.

Look at the load manuals to determine which will produce the most speed with the bullets you want to use. Most of those numbers are calculated with a 24" barrel and will be slower from a shorter barrel. But will still be faster than other powders.

 

[Charlie98]

I ran into this issue loading 7.62mm for my Socom16 vs the standard M1a's 22" barrel... where IMR4895 would be the standard, I had to drop down to the faster IMR3031 to get maximum performance out of the 16" barrel.

I use H335 for both my 16" and 20" AR's. Given that you are launching heavier bullets, I would probably start there and maybe drop down to H322/IMR3031 or even Rl10x to see if you get an improvement and/or reduced muzzle flash, there will most likely be a point of diminishing return somewhere.

 

[Kaldor]

I ran into this issue loading 7.62mm for my Socom16 vs the standard M1a's 22" barrel... where IMR4895 would be the standard, I had to drop down to the faster IMR3031 to get maximum performance out of the 16" barrel.

I use H335 for both my 16" and 20" AR's. Given that you are launching heavier bullets, I would probably start there and maybe drop down to H322/IMR3031 or even Rl10x to see if you get an improvement and/or reduced muzzle flash, there will most likely be a point of diminishing return somewhere.

As Charlie pointed out, you need a quicker burning powder for a shorter barrel. Id run H322 or possibly one of the 4198s.

I will say this, if you are chasing velocity in an SBR youre going to have issues. Dont bother. Concentrate on accuracy, function, and flash reduction first.

 

[Sam1911]

As Charlie pointed out, you need a quicker burning powder for a shorter barrel

Why, exactly? You should always follow up a statement like that with the results you're looking for.

A faster burning powder wouldn't give you higher velocities than a slower one. It might give you less flash -- but that's way more affected by your choice of an effective flash-hider/muzzle brake than powder on an AR. What else does a quicker burning powder do for you?

 

[Kaldor]

Why, exactly? You should always follow up a statement like that with the results you're looking for.

A faster burning powder wouldn't give you higher velocities than a slower one. It might give you less flash -- but that's way more affected by your choice of an effective flash-hider/muzzle brake than powder on an AR. What else does a quicker burning powder do for you?

Sam, a faster burning powder will help because you can actually get a full burn in a 10.5" barrel whereas something like CFE223, Varget will not burn completely, and you are just blowing unburnt powder out the end of the barrel, thus you are not getting the full velocity potential for your setup. One other powder that might work for you is IMR 8208 XBR. Short cut extruded, has about the same burn rate as H4895, but much easier to work with it, and you can get more of it in the case without heavy compression. With the heavier bullets youll need a little bit slower powder to drive the longer heavier bullets to higher velocity. A fast powder like H322 or 4198 might see early pressure signs with a longer bullet like a 69gr, but will work great with a 55gr.

You can control flash with the right muzzle device, but if you are getting alot of flash, thats a sign that you also have alot of unburnt powder flying out the end of the barrel.

This is one of the reasons I dont recommend long burning powders like Varget in 223 without a minimum of a 18" barrel and a rifle length gas system. It artificially increases port pressure on the gas system which over works the action, and the only real solution for that is to use an adjustable gas block. Hornady has an excellent graphic on using their Superformance powders in gas guns that shows exactly what happens but I cant find it.

With short barrels and heavy projectiles is a very fine balancing act. Longer barrels give alot more flexibility. My advice is this: Buy a pound of H322, H335, 8208 XBR and test velocity, accuracy, and flash. I know you will see the highest velocity with the 8208 for the heavier bullets. For 50-60gr bullets, H335 or H322 will probably be the best bet. Only you can determine what you want. For me? Accuracy > all.

 

[Sam1911]

Sam, a faster burning powder will help because you can actually get a full burn in a 10.5" barrel whereas something like CFE223, Varget will not burn completely, and you are just blowing unburnt powder out the end of the barrel

This is a bit of an old wives' reloader's tale that doesn't really happen. As jmr40 pointed out, all the powder is burned in a very few inches of barrel.

thus you are not getting the full velocity potential for your setup

The gas produced by the burned powder continues to expand, and if it is contained within the bore of a longer barrel, it will produce higher velocities.

However, there isn't any reason to think you'll get higher velocities out of a short barrel because you use a faster powder than a slow one. All things being made equal, the slower powder still produces higher velocities than the faster one. If that was the case, you'd get faster velocities out of a longer barrel with fast powder, too. About all you can say is that a shorter barrel doesn't optimize all you can get out of your powder.

 

[Kaldor]

This is a bit of an old wives' reloader's tale that doesn't really happen. As jmr40 pointed out, all the powder is burned in a very few inches of barrel.

Possibly. But until I see absolute proof that their isnt, Ill always tailor the powder to the rifle and bullet. There is no magic combination, there is only what safely works best for you.

You follow what Im saying on the rest of my points?

 

[Sam1911]

I edited while you were posting your reply.

Yes, I completely agree that you need to try a variety of powders to figure out what your specific gun likes, with the exact bullet (weight) you'll be using. Your most accurate load probably won't be either the slowest powder in the book, or the fastest, or your highest velocity load necessarily, either.

 

[Walkalong]

While the faster powder may give a better burn (Less residue/smoked up cases), depending on the application, it will never give higher velocities at max pressure. It may also have less flash and recoil, but not more velocity.

And whether or nor your particular gun likes one or the other accuracy wise, it still doesn't mean a faster powder is better suited overall, just in that particular case.

The slower powders (Until you can't get enough in the case to get max pressure) will always give more velocity. Even in short pistol barrels.

 

[Walkalong]

Ill always tailor the powder to the rifle and bullet. There is no magic combination, there is only what safely works best for you.

Agreed.

 

[Toprudder]

I have an 8.5" barrel AR pistol. While the normal loads I had worked up for my 20" rifle worked well (within the limitations of iron sights @ 50 yards) I was getting an obnoxious muzzle blast and flash that was annoying. I looked for the fastest burning powder that I had, which was H4198. This powder worked very well in my AR pistol at the min charge of 19.0gn with cheap 55fmj bullets. Now I have not done any testing for accuracy @ 100 yards, I was just looking for reasonable accuracy on paper at 50 yards. I have no plans or expectations to shoot this past 50 yards anyway.

IMHO, if you want max velocity, you will need a slower burning powder, but the tradeoff will be muzzle blast and flash.

 

[Walkalong]

IMHO, if you want max velocity, you will need a slower burning powder, but the tradeoff will be muzzle blast and flash.

Yep, especially in a very short barrel. Never had any use for AK or AR pistols. I don't like lots of muzzle blast.

 

[rbernie]

This is a bit of an old wives' reloader's tale that doesn't really happen. As jmr40 pointed out, all the powder is burned in a very few inches of barrel.
...
The gas produced by the burned powder continues to expand

I'm gonna wordsmith this a bit:

While the amount of gas that is produced is fixed by the amount of propellant used and cannot itself increase beyond propellant burnout, and while propellant burn-out occurs some 2"-5" past the cartridge mouth, bullet acceleration will continue past propellant burnout so long as the force from the continued presence of high pressure gasses behind the bullet is greater than the friction acting on the bullet.

 

[Walkalong]

Well said.

 

[Ironicaintit]

I tend to lean towards faster powders. One of my most accurate loads is a 55 gr SMK over 21.5 gr of IMR4198, whether it be out of a pistol, carbine, or rifle length.
Loads with a heavier bullet will get a slower powder, but barrel length doesn't even factor into my equation.

 

[kwg020]

I have a skinny barrel Mini 14 and I definitely get better accuracy out of faster burning powders. (RL10x, AA2015, IMR 3031) But I'm sure I am losing velocity. Not that I would take velocity over accuracy. I'll sacrifice the velocity.
kwg

 

[Toprudder]

Yep, especially in a very short barrel. Never had any use for AK or AR pistols. I don't like lots of muzzle blast.

I got an AR pistol just to play with. If all I had to shoot were factory loads, it would not be very pleasant. With the min charge of H4198, it shoots with reduced recoil and flash, and is much more pleasant to shoot as a result. With a 22LR CMMG conversion installed, it is a real hoot.

 

[Charlie98]

I got an AR pistol just to play with. If all I had to shoot were factory loads, it would not be very pleasant. With the min charge of H4198, it shoots with reduced recoil and flash, and is much more pleasant to shoot as a result.

I had the.... pleasure... of shooting in an indoor range next to an AR pistol last weekend. The concussion and muzzle blast was about what I expected... I'm just glad that by the time he had it up and running, I was packing up to leave.

 

[Walkalong]

With a 22LR CMMG conversion installed, it is a real hoot.

I bet.

 

[Toprudder]

I had the.... pleasure... of shooting in an indoor range next to an AR pistol last weekend. The concussion and muzzle blast was about what I expected... I'm just glad that by the time he had it up and running, I was packing up to leave.

Then you probably would NOT like being in the lane next to me when I shoot my S&W 460.