308 Barrel Length question.

[MudRunner2005]

I have a Rem. 700 SPS Varmint in 308 with a 26" bbl. 1 in 12 twist, with a Witt clamp on brake. I am wanting to go shorter for packing around. This rifle shoots under moa with 155 and 168 grain bullets. Thinking of going 20" with a 2" brake. I'm not really concerned with the 168's, but is this long enough to get the 155's up to speed, or do I need at least 24"? Any input would be appreciated.

Personally, I'd keep it a 26"....Minimum 24. My current .308 Win is a Rem 700 5R MilSpec w/ the 24" barrel. Tack-driver of a rifle, for factory untouched, other than replacing the trigger and retorquing the action screws to 65 inch-lbs.

I had a 20" custom .308 built off a Rem model 7 action. I didn't have chronys back then, and I wasn't reloading, but it shot factory Hornady red box (LE) TAP 168 BTHP's like fire. It would put 3 into the exact same hole if I did my part. Being a 20" barrel, I'm sure it wasn't the fastest rifle out there, but it sure was handy for carrying around, and was more than capable out to 500 yards.

Just food for thought.

But if you plan on taking it much farther than 500-600 yards, I'd look at 24" minimum, but possibly leaving it at 26" for maximum effectiveness.

Also, with your 1:12 twist, you can shoot up to 190gr Berger VLD's.

I have this EXACT same barrel you have, that I built a custom with, and had the chamber opened up to .30-06 Ack Imp. I shoot the 185 VLD's, and the load has been estimated (according to QuickLoad) to be around 2,900 fps.

 

[MontanaMarine]

Are you shooting 208's with a 1 in 12" twist?

Yes.

I've played with a few of the longer bullets in the 1/12, with good results. Here's a few.

 

[MontanaMarine]

In my opinion/experience with the 308, the key decision for long range performance is more associated with bullet choice than barrel length (within reason).

I shoot my 20.5" to 1200 yards fairly regularly, with the 208 AMax. At that distance It's still going 1400+ fps. (2550 fps mv, elevation 4000' ASL).

Between 22-26", you only talking about a difference in MV of maybe 60-70 fps with a 308 Win. Selecting a bullet with a BC over .6 will keep you supersonic further than starting a bullet at .5 BC a few fps faster via 2-4" more barrel.

The 215 gr Berger VLD at BC .696 is a wicked bullet in the 308. In a limited load test, I started them at 2600 fps in a 26" bbl. If you run the external ballistics on that, you will see it is impressive for a little 308 Win. Far more gain than starting a 175 gr SMK 60 fps faster.

 

[Canadian Bushman]

The 215 gr Berger VLD at BC .696 is a wicked bullet in the 308. In a limited load test, I started them at 2600 fps in a 26" bbl. If you run the external ballistics on that, you will see it is impressive for a little 308 Win. Far more gain than starting a 175 gr SMK 60 fps faster.

Even at 2500fps the 215 is pretty impressive.

Shane, Did you see any increase in accuracy when you shortened your barrels?

 

[MontanaMarine]

Maybe a slight improvement in accuracy. Physically, the shorter barrel would be a bit stiffer, so it seems possible.

Here's a 10-shot 'reality check" at 100 yards, with the 20.5" 308, and 208 AMax,

 

[Canadian Bushman]

Looks like a solid 10 shot group to me.

 

[MudRunner2005]

Have you tried the Berger 210 or 215's in a 12" twist barrel?

Reason being, I was wondering how the 210VLD's might do in my .30-06 AI, that has a 26" 1:12 barrel that was originally a Rem 700 Varmint .308 barrel.

 

[MontanaMarine]

Yes both the Berger 210 and 215.

The 210 VLD shot exceptionally well in the 1/12 308. Berger suggests 1/11 as optimum for the 210 VLD.

Here's a five-shot group with the 210 Berger, They were not always THIS tight, but .5 moa was pretty normal, I was loading RL-15 under them in those days, getting about 2500 fps.



The only reason I migrated away from the 210 Berger, to the 208 AMax, was cost.





I shot only a few of the 215's that Broz gave me for a test. They shot fairly well from the 26" 1/12 308, at 2600 fps. Here's a pic. As you can see, the shorter 20.5" barrel was shooting a bit loose. They had to be pretty close to the edge on stability. I only had enough for a 100 yard test.






I've also had good results with the Hornady 225gr BTHP. They shot well at 100 yards, and also out to 1200 yards, with an apparent BC of about .710 based on 1200 yard corrections.





I'd always choose a 1/10 twist given the choice, but with the factory 1/12, a lot of long bullets work, that aren't supposed to.

 

[MontanaMarine]

I don't have a lot of pics of long range groups, as I tend to shoot a lot of rocks and stuff like that.

But to try to quantify some downrange ability, here is an old pic of a target I was shooting at 1120 yards. This wa with a 208 AMax at 2480 fps, via RL-15, and a 22" 1/12 factory barrel. Scope was a Leupold MK4 3.5-10x40.

Target is 15" wide, 25" tall. The black square is 5x5".

 

[MudRunner2005]

Yes both the Berger 210 and 215.

The 210 VLD shot exceptionally well in the 1/12 308. Berger suggests 1/11 as optimum for the 210 VLD.

Here's a five-shot group with the 210 Berger, They were not always THIS tight, but .5 moa was pretty normal, I was loading RL-15 under them in those days, getting about 2500 fps.



The only reason I migrated away from the 210 Berger, to the 208 AMax, was cost.

I shot only a few of the 215's that Broz gave me for a test. They shot fairly well from the 26" 1/12 308, at 2600 fps. Here's a pic. As you can see, the shorter 20.5" barrel was shooting a bit loose. They had to be pretty close to the edge on stability. I only had enough for a 100 yard test.

I've also had good results with the Hornady 225gr BTHP. They shot well at 100 yards, and also out to 1200 yards, with an apparent BC of about .710 based on 1200 yard corrections.

I'd always choose a 1/10 twist given the choice, but with the factory 1/12, a lot of long bullets work, that aren't supposed to.

Good to know! I guess I'll give them a try in the .30-06 AI.

I shoot the 210 VLD's in my .308 Win (24" 5R Milspec 11.25 twist), and it shoots groups like your 210 VLD group.

Thanks again for the info.

 

[Nomosendero]

In my opinion/experience with the 308, the key decision for long range performance is more associated with bullet choice than barrel length (within reason).

I shoot my 20.5" to 1200 yards fairly regularly, with the 208 AMax. At that distance It's still going 1400+ fps. (2550 fps mv, elevation 4000' ASL).

Between 22-26", you only talking about a difference in MV of maybe 60-70 fps with a 308 Win. Selecting a bullet with a BC over .6 will keep you supersonic further than starting a bullet at .5 BC a few fps faster via 2-4" more barrel.

The 215 gr Berger VLD at BC .696 is a wicked bullet in the 308. In a limited load test, I started them at 2600 fps in a 26" bbl. If you run the external ballistics on that, you will see it is impressive for a little 308 Win. Far more gain than starting a 175 gr SMK 60 fps faster.

I am impressed with not only the accuracy but the velocity of your 215 Berger load. Nice thing is I have some RL17.