Anybody have any data for 18 or 20'' 308 barrels?

Austincqc

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I have a 10fp with a 24 inch barrel. She shot really well this last weekend when I was breaking her in. I'm going to find a good gunsmith around the Central TX area to cut her down to either 20 or 18 inches...or maybe somewhere in between.

I'm starting to reload and saving all my brass, so I wanted to see if anybody had any suggestions for commercial or handloads either barrel length (ie. I have an 18 inch and 20 and 168gr Fed works the best for the 18 and 175gr for the 20...) or if anybody had any data on which ammo lost the least amount of MV, etc...

Thanks all!
 

Austincqc

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Re: Anybody have any data for 18 or 20'' 308 barrels?

Cool. Thanks! I'll look there. Can anybody offer any commercial ammo suggestions for the time being?
 

BeerAlchemist

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Re: Anybody have any data for 18 or 20'' 308 barrels?

You might want to look at the impact of short barrels on .308 loads...it takes something like 18.5 - 20 inches (if I remember right) for the powder to burn completely depending on the powder. If you load with slower burning powders an 18" barrel won't work for you. This might help with your question though (actually the whole article is good info):

"During the development of the Tango 51, Tac Ops took a standard 26-inch barrel and cut it down to 18 inches in one-inch increments. Between 10 to 20 rounds were fired at each invrement. They found that a 20-inch barrel provides for a complete propellant burn and no velocity loss when using Federal Match 168-grain BTHP, a cartridge that has become something of a law enforcement standard. Going to an 18-inch barrel only resulted in a loss of 32 feet per second (fps)."

http://www.tacticaloperations.com/SWATbarrel/
 

Austincqc

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Re: Anybody have any data for 18 or 20'' 308 barrels?

yeah, I read that article before buying my rifle. There is so much good info out there...kinda hard to believe people still assume a longer barrel is better.

I'm really new to reloading, so I'm not too familiar with fast vs slow powders. The notion of a faster burning powder being needed in shorter barrels makes complete sense. I saw Lowlight's video with his gladius and corbon 175gr ammo. So at least there is some commercial stuff that an 18 inch barrel will digest well.

I'm starting to think 20 would be a safe length and short enough.
 

ranger1183

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Re: Anybody have any data for 18 or 20'' 308 barrels?

If you are concerned about maximum powder burn for an 18" .308 barrel, I would switch from Hodgdon Varget to Hodgdon Benchmark. Benchmark is also a very temperature stable powder.

Start at 40 grains of Benchmark (if you are shooting 168 or 175 grain SMK's) and work your way up [carefully]. You'll get over 99% powder burn.

my ¢2
 

bohem

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Re: Anybody have any data for 18 or 20'' 308 barrels?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AustinCQC</div><div class="ubbcode-body">kinda hard to believe people still assume a longer barrel is better.
</div></div>

Under a very specific set of load conditions you're right.

Once you step out of the realm of fast (for that chamber) powders, medium weight bullets (for 30 cal) and light (again, for 30 cal) capacity cases it's a very different story.

Keeping what I said in mind, an 18"-20" barrel on a 223 is pretty long if you shot medium weight bullets (55's) with fast (H335) powder.

The 223 is relatively light in capacity when you look at centerfire 22's. 22-250 is upper/medium, then you get to things like 22-243, 22-284, 220 Swift, 22-06.

Given the specific set of load conditions I spec'd for a 223 you have complete powder burn in about 12.5-14" depending on the specific load. So other than the legal ramifications of cutting a rifle down that far you could say the same thing about a 14" barreled SPS 223.

If you loaded 190's and RL17 in the 308 or 75-90's in the 223 with IMR4064 you have a totally different answer where a short barrel isn't optimal.
 

Austincqc

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Re: Anybody have any data for 18 or 20'' 308 barrels?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">

Under a very specific set of load conditions you're right.

Once you step out of the realm of fast (for that chamber) powders, medium weight bullets (for 30 cal) and light (again, for 30 cal) capacity cases it's a very different story.
</div></div>

Well I said people "assume" that longer barrels are better. The same can be said for huge monster gas guzzling engines making your car faster. I'm sure there are loads and bullets that would best benefit from a longer barrel just as there are types of cars that benefit from a lighter higher revving engine.

I'm glad there are shooters like you out there.

It's just annoying when people make assumptions.
 

hypertex

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Re: Anybody have any data for 18 or 20'' 308 barrels?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AustinCQC</div><div class="ubbcode-body">... or if anybody had any data on which ammo lost the least amount of MV, etc... </div></div>

Heavier bullets like the 208AMAX, mine start at 2335 and are still 1250fps at 1000yds. And that's magazine-fed in an 18" DPMS SASS using H4895

Tried to move up to Benchmark powder, but couldn't get the velocity even with uber-max loads -major cratering. Was just able to nudge 2300fps
Maybe the bolt gun will fare better than my semi-auto
 

bohem

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Re: Anybody have any data for 18 or 20'' 308 barrels?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AustinCQC</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">

Under a very specific set of load conditions you're right.

Once you step out of the realm of fast (for that chamber) powders, medium weight bullets (for 30 cal) and light (again, for 30 cal) capacity cases it's a very different story.
</div></div>

Well I said people "assume" that longer barrels are better. The same can be said for huge monster gas guzzling engines making your car faster. I'm sure there are loads and bullets that would best benefit from a longer barrel just as there are types of cars that benefit from a lighter higher revving engine.

I'm glad there are shooters like you out there.

It's just annoying when people make assumptions. </div></div>

Yep, I didn't mean it as an argument, I wanted to put a clarification in there to some of the stipulations where they're equivalent or a shorter barrel is better for other people that might read the thread and have an incomplete picture. There's a lot of lore regarding barrel length, both short and long, but the technical considerations of each is not usually discussed, that's all I was trying to do.

See ya 'round.
 

Austincqc

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Re: Anybody have any data for 18 or 20'' 308 barrels?

I'm trying to make a good medium distance pack .223. I'm definitely going to test what you said and try to find a load that works best on a 16" barrel.