.308 Bullet and powder selection for 18" barrel

[.308 garand]

I haven't reloaded .308 in a while and am needing to pick up some supplies. I know each gun is different and I'll have to find what works for my gun, I'm just trying to establish a starting point. I had a few questions about the 168gr vs 175/178gr and also about Varget vs IMR 4064.

I have always loaded heavy for caliber bullets -
In a shorter barrel will the speed of the 168s cancel out the bc of the 175s?

90% of my shooting will be under 800yrds
Are the 175s worth it or should I go with 168s?

Lastly I have a little Varget and a little 4064 but will need to get more of one. I've heard good things about both.
Any reason to pick one over the other with the short barrel?

 

[jwrowland77]

If it was me, and I was shooting out to 800, I would definitely go with the 175gr. The 168's lose stability after about 600yds.

As far as powder goes, I haven't tried either one. I do have a load though with 175's pushing 2650fps out of a 22" barrel.

What's your twist rate for your rifle?

 

[.308 garand]

Twist rate is 1:10.

 

[jwrowland77]

You shouldn't have any issues pushing a 175 with a 1:10 twist rate. I shoot mine out of a 1:12 twist with a 1.678 stability factor

Edit:
If you run the 175's in a 1:10 @2600fps you'll get 2.4 stability factor using the jbm calculator. I forgot to ask what bullet you used. I calculated for SMK.

 

[hdbiker]

I have owned a Rem 742 carbine with a 181/2 inch barrel in .308 Win for 40 years. After years of trying different powders and bullet combinations, I find 45 grains of IMR 4064 under a 165 grain spritzer bullet gives me 2 1/2 inch groups at 100 yards. I know that's not great accuracy, but that's the best it will do. I use for heavy woods hunting where quick snap shots are the norm. It runs plus or minus 2700 fps. I've killed 50 to 60 deer with it. hdbiker

 

[.308 garand]

What kind of velocity is everyone seeing with a shorter barrel? What kind of real world numbers are you guys getting?

 

[ArchAngelCD]

With 30 Cal cartridges I do not feel changing powders for a shorter barrel is necessary. A good .308 load is a good .308 load. Barrel length has nothing to do with accuracy. If you get an accurate rifle it won't matter if it has an 18" or 22" barrel.

I'm a huge fan of IMR4064 for loading the .308 Win. If there is a better powder I haven't found it although I'm sure one might be out there.

 

[rcmodel]

Pick your powder based on performance and accuracy.
Not barrel length.

Whatever powder gives the highest published velocity in a long barrel, will also give the highest velocity in a short barrel.

And BC is always BC.
The highest number BC will remain so, regardless of barrel length.

rc

 

[LocoGringo]

I haven't tried either IMR4064 or Varget in my 18.5" barreled AR, but I use H4895 with the 175 SMK and get .75-.5" 5-shot groups with the velocity averaging 2570 FPS in warmer weather.

Varget is my "go to" powder for my 24" barreled bolt action .308 with the 175 SMK. I get 2712 fps out of it with SD of +/- 14 FPS and .5" 5-shot groups if I'm shooting well.

 

[gamestalker]

As Arch said, a .308 is a .308. So what ever powder works well for a 22" is going to work just as well in an 18", not considering variables aside from barrel length of course, as every firearm is different of course.

GS

 

[Swampman]

@ .308 garand

I agree with the advice given earlier regarding powder selection, the best powder is likely to be the best whether your barrel is 22 or 18 inches long.

I'm assuming from your monicker that these loads are to be fired out of a Garand, if so, I'd urge you to consider using either the Sierra 155 grain Palma MatchKing or the Lapua 155 grain Scenar.

Both of these bullets are very close to the claimed BC of the 175 grain MatchKing (the Scenar is actually higher), but their lighter weight will allow you to push them faster without trashing your op rod.

While I love the 168 grain MatchKings at 600, I don't think they'll work well for you at 800, particularly when you factor in your action and barrel length.

 

[.308 garand]

The rifle in question is a bolt gun.

 

[jmr40]

What kind of velocity is everyone seeing with a shorter barrel? What kind of real world numbers are you guys getting?

I used to own a 20" gun. I got 2700 fps with 168's using 46 gr of Varget.

Here are some results from 18" barrels.

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