Best loads for 16" 308 semi auto?

dvdcrr · October 17, 2015, 11:55 PM

I am looking for recommendations regarding a load (or factory load) for 16" semi auto 308 rifles. Specifically I am interested in producing best velocity while possibly minimizing muzzle flash. Are there any known loads which produce good speed in a 16" tube? Thanks

Kosh75287 · October 18, 2015, 02:05 AM

I don't have any specific loads worked up, but a relatively fast-burning rifle powder like IMR 3031 might be the way to go. You don't mention what projectile weight you desire, but I would expect 3031 to give you decent velocity up to 165 grains, perhaps heavier. Another possibility is AA# 2015, which should meter through a powder measure somewhat easier.

You might inquire of powder manufacturers for suggestions. I think there are a few powders available that may have flash suppressants in their formulation. I'd make a decision on what projectile weight you want, first.

Another consideration is whether a particular powder is too fast-burning or slow-burning to work well in the action of semi-autos. Garands are somewhat famous for needing powders with burn rates in a fairly narrow range. Later designs, especially the ones with adjustable gas regulators are somewhat more forgiving in this respect. I'd be surprised to find that 3031 is too fast burning to work in a modern semi-auto, but AA#2015 might be.

Hodgdon H335 was formulated to burn a 25.0gr. charge completely in a 20" barrel behind a 55gr. .224" FMJBT projectile. A .308" barrel of equal volume would be @ 10.6" long, but the powder charge for a 150gr. .308 load using H335 is larger by a factor of 1.7. Your 16" barrel is longer by a factor of 1.5, which may be close enough to 1.7 to give H335 a try.

This is an extremely rough approximation I'm making, and is complicated by projectile weights differing by a factor of 2.7 to 3.0. But the algebra involved suggests to me that rifle powders with burning rates between 3031 and H335 may be the most likely to burn completely in a short .30 caliber tube.
Ultimately, it's going to come down to trying various powders and finding out, but perhaps I've narrowed the search for you.
Hodgdon Benchmark is faster burning (depending on the burn-rate chart) than H335, and may be worth trying. Alliant Reloader 10X (if you can find it) might also work.

steve4102 · October 18, 2015, 06:18 AM

Quote:

Generally speaking the fastest powder with the longest barrel is usually the fastet powder with a shorter barrel (within reason).

http://thefiringline.com/forums/showthread.php?t=528969

Mike / Tx · October 18, 2015, 06:20 AM

I have hunted with a Ruger Compact in 308 for close to 15 or so years give or take. While its a bolt action the tube is only 16.5". I shot Rem 150gr CL's in it until ibran out of my $10 a box supply. I never noticed much if any flash even shooting hogs at night.

When I was down to my last box of the cheap stuff in broke down and worked up a load using H4895 which except for a touch better accuracy duplicated the CL loads including minimal flash that I have seen.

dvdcrr · October 18, 2015, 04:30 PM

Any thoughts on cfe 223?

gunfighter48 · October 20, 2015, 11:54 PM

I haven't started reloading 308 yet but I can tell you what factory ammo shoots best out of my LR308 16" barreled rifle. So far all the 168gr ammo is very accurate, less than 1/2MOA at 100 yards with Hornady 168gr TAP and AMAX. My barrel is a 1-10 twist rate.

Mobuck · October 21, 2015, 06:22 AM

"Specifically I am interested in producing best velocity while possibly minimizing muzzle flash."
General recommendation would be to stick with the "faster" end of the suitable powders. Slower powders are more likely to produce more muzzle flash.

jmr40 · October 21, 2015, 06:03 PM

I get good speeds in my 22" and 18" guns using Varget, RL15, and 4064. These are bolt rifles, you might run into cycling issues in a semi with the same load though. The powders that give the best speeds with a long barrel will also give you the best speeds with the shorter barrel. Can't comment about muzzle flash, but I don't have any issues with my 18" barrel with any of the above.

Mike / Tx · October 22, 2015, 04:12 AM

Quote:

you might run into cycling issues in a semi with the same load though.

Quote:

Slower powders are more likely to produce more muzzle flash.

One thing as mentioned above, is the cycling. You will need to hit a specific range for reliability, but the slower powder may not be what your after here. Some of them will produce more pressure on your slide than the faster powders will and could possibly damage something.

I would stick with the mid range powders, and unless your getting fireballs like a full charge of 296 blows out, I wouldn't be overly concerned. Most of the powders I have used in the mid range have only given a dull orange glow, but it wasn't visible from the rear of the rifle, only from the side.

Now if your hunting at night with night vision this throws another link into the chain, but there are plenty of folks doing that here in TX for hogs, and I haven't heard of it being much of an issue.

October 17, 2015, 11:55 PM	#1
dvdcrr Senior Member Join Date: July 5, 2010 Posts: 665	Best loads for 16" 308 semi auto? I am looking for recommendations regarding a load (or factory load) for 16" semi auto 308 rifles. Specifically I am interested in producing best velocity while possibly minimizing muzzle flash. Are there any known loads which produce good speed in a 16" tube? Thanks __________________ "All warfare is based on deception. Hence when we are able to attack we must seem unable....when using our forces we must appear inactive. When we are near we must make the enemy believe we are far away."Sun Tzu The Art of War.

October 18, 2015, 06:20 AM	#4
Mike / Tx Senior Member Join Date: April 8, 2000 Posts: 2,102	I have hunted with a Ruger Compact in 308 for close to 15 or so years give or take. While its a bolt action the tube is only 16.5". I shot Rem 150gr CL's in it until ibran out of my $10 a box supply. I never noticed much if any flash even shooting hogs at night. When I was down to my last box of the cheap stuff in broke down and worked up a load using H4895 which except for a touch better accuracy duplicated the CL loads including minimal flash that I have seen. __________________ LAter, Mike / TX

October 18, 2015, 04:30 PM	#5
dvdcrr Senior Member Join Date: July 5, 2010 Posts: 665	Any thoughts on cfe 223? __________________ "All warfare is based on deception. Hence when we are able to attack we must seem unable....when using our forces we must appear inactive. When we are near we must make the enemy believe we are far away."Sun Tzu The Art of War.

October 20, 2015, 11:54 PM	#6
gunfighter48 Senior Member Join Date: July 8, 2006 Location: Mill Creek, WA Posts: 167	I haven't started reloading 308 yet but I can tell you what factory ammo shoots best out of my LR308 16" barreled rifle. So far all the 168gr ammo is very accurate, less than 1/2MOA at 100 yards with Hornady 168gr TAP and AMAX. My barrel is a 1-10 twist rate. __________________ gunfighter48 A 45 may not expand but it will never be smaller than .45!! NRA Benefactor Life Member

October 18, 2015, 02:05 AM	#2
Kosh75287 Senior Member Join Date: October 15, 2007 Posts: 820	I don't have any specific loads worked up, but a relatively fast-burning rifle powder like IMR 3031 might be the way to go. You don't mention what projectile weight you desire, but I would expect 3031 to give you decent velocity up to 165 grains, perhaps heavier. Another possibility is AA# 2015, which should meter through a powder measure somewhat easier. You might inquire of powder manufacturers for suggestions. I think there are a few powders available that may have flash suppressants in their formulation. I'd make a decision on what projectile weight you want, first. Another consideration is whether a particular powder is too fast-burning or slow-burning to work well in the action of semi-autos. Garands are somewhat famous for needing powders with burn rates in a fairly narrow range. Later designs, especially the ones with adjustable gas regulators are somewhat more forgiving in this respect. I'd be surprised to find that 3031 is too fast burning to work in a modern semi-auto, but AA#2015 might be. Hodgdon H335 was formulated to burn a 25.0gr. charge completely in a 20" barrel behind a 55gr. .224" FMJBT projectile. A .308" barrel of equal volume would be @ 10.6" long, but the powder charge for a 150gr. .308 load using H335 is larger by a factor of 1.7. Your 16" barrel is longer by a factor of 1.5, which may be close enough to 1.7 to give H335 a try. This is an extremely rough approximation I'm making, and is complicated by projectile weights differing by a factor of 2.7 to 3.0. But the algebra involved suggests to me that rifle powders with burning rates between 3031 and H335 may be the most likely to burn completely in a short .30 caliber tube. Ultimately, it's going to come down to trying various powders and finding out, but perhaps I've narrowed the search for you. Hodgdon Benchmark is faster burning (depending on the burn-rate chart) than H335, and may be worth trying. Alliant Reloader 10X (if you can find it) might also work. __________________ GOD BLESS JEFF COOPER, whose instructions, consultations, and publications have probably saved more lives than can ever be reliably calculated. DVC, sir. انجلو. المسلحة. جاهزة. Carpe SCOTCH! Last edited by Kosh75287; October 18, 2015 at 03:20 AM. Reason: Additional information

October 21, 2015, 06:22 AM	#7
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	"Specifically I am interested in producing best velocity while possibly minimizing muzzle flash." General recommendation would be to stick with the "faster" end of the suitable powders. Slower powders are more likely to produce more muzzle flash.

October 21, 2015, 06:03 PM	#8
jmr40 Senior Member Join Date: June 15, 2008 Location: Georgia Posts: 10,822	I get good speeds in my 22" and 18" guns using Varget, RL15, and 4064. These are bolt rifles, you might run into cycling issues in a semi with the same load though. The powders that give the best speeds with a long barrel will also give you the best speeds with the shorter barrel. Can't comment about muzzle flash, but I don't have any issues with my 18" barrel with any of the above.