Need .308 recipies for 16.5" barrel.

[miko]

I am looking for military-type ammo - 168 and 150 grains or whatever are the standard weights.
I understand that the standard 308 ammo is optimised for longer barrels - 22-24 inches, so in 16.5 inch barrel (Rem 7600P pump I am considering) it will not be efficient, as well as cause a huge flash.

Am I correct that a faster-burning powder, possibly in smaller amount, will be more efficient, produce less flash and possibly more velocity than a standard ammo?

Has anyone experimented with such recipies?

Thanks,
miko

 

[Jim Watson]

You load for a 16.5" .308 the same way you load for any other.
Fast burning powders do not really make up for shorter than standard barrels.
I do not know what you mean by "more efficient". What is that?

You might get less muzzle flash from a faster powder, but you could shop around and get more or less flash from any burning rate powder depending on chemistry.
There is no possibility that a faster powder will give higher velocity. Might give better accuracy, but anything could do that.

 

[Grumulkin]

What's not to like about muzzle flash? Three feet of flame can be pretty impressive!

I tried some loads with IMR 4064 (the same I use in longer barrel 308s) in a 308 Win. handgun. The accuracy was good and the muzzle flash wasn't excessive.

 

[USSR]

Jim is correct, you do not get higher velocity in a short barrel by going to a faster burning powder. You will reach high pressure long before that. IMR4895 is a good powder for your use. Here are some loads that work well with LC brass:

147-150gr bullet
LC brass
WLR primer
43.0gr IMR4895

168gr bullet
LC brass
WLR primer
42.0gr IMR4895

Don

 

[miko]

You load for a 16.5" .308 the same way you load for any other.

That cannot possibly be true. A standard load performs well in 24" barrel - burning for a long time that it takes the bullet to travel through it.
Now, imagine the 8 inches lopped off - a whole lot of powder will end up burning outside the barrel.

That wasted powder will add nothing to bullet energy, but will add to recoil due to it's weight being expelled, not to mention the blinding flash, as well as cost.

Fast burning powders do not really make up for shorter than standard barrels.

They may not make up the loss of velocity due to the shorter barrel - that's true.
But they can propel the bullet to the same velocity by completely burning a lesser amount of powder - for reduced recoil (significant in a 7-pound gun), much reduced flash and lower cost.

I do not know what you mean by "more efficient". What is that?

By "more efficient" I mean that all the weight and energy of the powder is used to propel the bullet rather than create audio-visual effects and bruising.

I tried some loads with IMR 4064 (the same I use in longer barrel 308s) in a 308 Win. handgun. The accuracy was good and the muzzle flash wasn't excessive.

Interesting. Have you had a chance to shoot in poor light? During the day, I do not notice any flash out of 2" snub shooting .357 magnums, but at night it's another matter altogether...

Also, for all we know, the muzzle flash was not excessive because much of the powder ended up unburned. It's great that it was accurate, but if you can use less powder to accomplish that, why not do so?


Thanks for replies, guys.
miko

 

[Jim Watson]

If you already knew the answer, why did you ask?

I disagree with a lot of your points and conclusions, but why argue? Shoot the gun and you tell us what happens. Be sure to have a chronograph set up, you cannot reliably judge performance by feel and noise.

 

[R.W.Dale]

That cannot possibly be true. A standard load performs well in 24" barrel - burning for a long time that it takes the bullet to travel through it.
Now, imagine the 8 inches lopped off - a whole lot of powder will end up burning outside the barrel.

That wasted powder will add nothing to bullet energy, but will add to recoil due to it's weight being expelled, not to mention the blinding flash, as well as cost.

Shows what you know, It's an oft repeated MYTH that powder is still burning thorough a bullet's entire trip down the barrel. ALL OF THE POWDER THAT WILL BURN WILL DO SO IN THE FIRST THREE OR FOUR INCHES OF BARREL.

As for slow or fast powders 9 times out of 10 the slow powder that produces the top velocities in a 24" rifle barrel will still be faster than the other powders in a 16" tube.

Am I correct that a faster-burning powder, possibly in smaller amount, will be more efficient, produce less flash and possibly more velocity than a standard ammo?

NO Your problem is your basing your knowledge on a bunch of completely wrong assumptions

 

[miko]

I appreciate your responses. I appologise that my posts came through as offenisve.

I haven't thought the matter through and automatically applied the considerations applicable more to pistol cartriges than to rifle ammo. I can see that in a practical range of applications, the top MV might well be achieved by the same powder in 16.5", considering that it does burn before half that distance.

I will certanly post whatever results I obtain but it may take a while.

miko

 

[Zak Smith]

miko,

As a hypothetical, if the faster powder that you used to reach "the same velocity" in the shorter barrel were shot in the longer barrel, the velocity would almost certainly more than the other slower powder used for comparison. The limiter is peak pressure, which happens within the first 6-9" of barrel. Everything else is on the downward slope of the pressure curve.

-z

 

[miko]

Right. If the powder burns up completely before the bullet exits the barrel, the rationale for reducing the amount of powder (and substituting faster one to keep the charge at desired pressure) is lost.

The data I've looked up shows, for example, 220 fps gain from 15" barrel to 24" barrel for the same .308 150grn load and about the same for the 168 grn.
Considering the curves, I would not be surpised that going from 15" to 16.5" inches adds 100fps and from 16.5 to 24 (the last 7.5") only another 120 fps or so.

That is quite surprising. It really seems to make little sense to use more than 18-18.5" for .308 - at least in military weapons, and 16.5" as quite viable.
I think I will buy that 7600P for less than $500 to get into the world of .308

miko

 

[Zak Smith]

It depends if you're trying to hit things at 300 yards vs. 800 yards.

 

[bltmonty]

I have been reloading for my 15" encore pistol for many years, and in six rifle calibers. Contrary to what has been said, I do get best performance from slightly faster powders. I always follow the load books but look for the fastest burning powder for the bullet/grain combination, and I will get much closer to rifle velocities than with the slower powders.

For example, in 308 winchester, I started with Vihtavouri 140 but moved to Vihtavouri 133; the same with 6mmbr--started with Varget but got best results with H4895; and in 223, started with Vn 133 but settled with VN 130. In 350 Rem mag, started with AA 2520, but got best results in AA 2230. In 6.5-284, started with H4350 but had to go to H414.

The exact same is true in my pistols--I get much better performance in my Kel-tec 3" 9mm barrel using faster pistol powders than in my 4.5" S&W.

I heard the advice that the best performance in 15 inch Encore pistols is obtained with the powder one uses to get the best results in rifle barrels. This is simply not true in all of my experience.

Barry

 

[Grumulkin]

I heard the advice that the best performance in 15 inch Encore pistols is obtained with the powder one uses to get the best results in rifle barrels. This is simply not true in all of my experience.

Of course, the definition of performance depends on which parameter is most important to you. My number one desire in working up any load is accuracy. I will take a slower more accurate load than a faster less accurate one any day.

 

[bltmonty]

Performance versus accuracy--great point. I forgot to address it. I did get excessive muzzle blast with the slower powders in all my 15 inch encore barrels, but I am not sure how that affected accuracy. I guess that's the result of using a rifle cartridge in a pistol barrel.

I never compared the accuracy of the slower powders with the faster. I just loaded the slightly faster powder until I achieved consistent velocities and accuracy and that showed no problems with pressure. And all of my encore loads have achieved sub MOA. I don't think one can argue that slower powders are inherently more accurate. I simply wanted a pressure curve that worked best with my 15 inch barrels.

Barry