Hart HV .308 barrel, 1-9" - what to do with it??

[Darryl Cassel]

MM

Every rifle cartridge/bullet combination has it's own accuracy range.

For instance, at the 1000 yd matches in Williamsport, the accuracy range for a 30 cal 220 grSierra MK is 3000 to 3040 FPS. This seems to be the velocity most people strive for in thierr 300 Weatherbys and wild cat rifles.

For the 240 gr Sierra MK---2850 to 3000 FPS seems to work for most at the 1000 yd range. That would be 2850 to 2900 FPS with the 9 twist.
Please understand, these rifles have at least 30" barrels on them.

For hunting, the speed is increased with large cases and longer barrels
For LR hunting out of my 300 Tomahawk which has a 34" barrel and A 10 Twist, I push the 240 gr at 3200 FPS and it is unreal at yardages to 1800 yds.

Just some added information to ponder.

DC

 

[MontanaMarine]

Thanks for the info Darryl,

I've been shooting 190gr SMK moly in my 30-06 at 2903 fps with 63gr RL-22 in Norma brass. I get pretty consistent .5 moa accuracy. My barrel is 26" #7 Douglas 1-10 twist.

I've been contemplating trying the 220 or even the 240s. I've heard they do pretty well at 1-10 twist, despite the 1-9 recommendation from Sierra on the 240s. Guessing I could achieve 2650-2700 with the 220s, and 2500-2550 with the 240s. Probably using around 61-63gr of RL-25.

If i can shoot 240s accurately at 2550 fps, it should hit at 1300 yards with about the same velocity as your Tomahawk at 1800. And with a mechanical accuracy of .5moa, I think that gives it potential to that distance.

I need to nose around at Weapons Training Battalion and see about getting on the 1000 yd range on the weekend. I guess that is the only way I will really know.

Do you think I would be wasting my time with the 220-240 gr matchkings?

MM

[ 11-21-2002: Message edited by: MontanaMarine ]

 

[BountyHunter]

[ 03-14-2004: Message edited by: BountyHunter ]

 

[MontanaMarine]

Bountyhunter,

In regards to shooting the 300WSM at deer at 600 yards, I do not understand what is impractical about dialing in 14 minutes of elevation, making a wind call, and hammering the target. I've made headshots on a human sillouette at 600yards with a lowly .308/168SMK, about 16 MOA up, and punched 5 shots into a 4" cluster.

It seems a quite simple task compared to cranking up 55MOA or thereabouts, and making the right wind call, to hit a target at 1800 yards with a 240SMK at 3200fps MV.

A laser would be a given, for me, to shoot a deer at 600, regardless of caliber choice.

You lost me with your correlation between a 300WSM/240grSMK and a .22 rimfire, for a 600 yard shot.

MM

 

[Darryl Cassel]

MM

I would stay with the lighter bullet weight you mentioned for the cartridge you are shooting.

Not only do you need added velocity, but with that, you also need the foot pounds of energy at extended range which the added velocity will give you with the larger case capacity and 240 gr bullets.


Have a good one.
DC

 

[Brent]

MM,
Oehlers Ballistic Explorer clearly gives the advantage to the 240gr SMK at 2550 over the other two in wind and energy, you pick your come ups, 47 to 51 MOA. I would have thought the light bullet also but I'd take the heaviest it would shoot first. Keep in mind that a range estimation error of 5 yards is about max even if you are capable of 1/2 MOA, would be less for sure if not. Wind drift is half that of the 240 at 3200 fps at 1800 yards also.

This is when you have to realize the limits of the rangefinder you're using for sure, and is definatly the outer limit no mater what range finder, for first round hits without spotter shots that is.

With Darryls at 3200 fps and a 1/2 MOA rifle at 1800 yards, a 5 yard error in range would mean a 15" high or low impact too. A spotter round is the only way here.

Remember a 1/2MOA rifle is not a true laser at this range and the 9" error is still there at 1800 yards.

[ 11-22-2002: Message edited by: Brent ]

 

[BountyHunter]

[ 03-14-2004: Message edited by: BountyHunter ]

 

[MontanaMarine]

Thanks guys for your feedback,

My interest in LR shooting is pretty limited by your standards. I like rifles I can carry around, 16-17 pounds/26-27" barrels, is the absolute heaviest I am willing to go. My 30-06 is about 15 lbs. .308 goes 12 lbs. Eventually I'm going to build a .338WinMag with a 27" #8 barrel, aiming for about 17 lbs.

I know these cartridges lack the ballistic stimulation of your 2000 yd, 416 based boomers. But I'm really only interested in maximum ranges of around 1000-1300 yards. Thats about the limit of my optics/cartridge/weight limit. A LRF 1200 is about all I am willing to spend on a laser as well.

Back in my Montana, at 4000 ft elevation, my cartridge choices deliver what I consider good performance out to 1300:

30-06/240grSMK@2550MV
Yards: 1300
Vel: 1354
Energy: 978.2
Traj: -47.8 moa

.338WM/300grSMK@2550MV
Yards: 1300
Vel: 1415
Energy: 1334
Traj: -46.1 moa

This performance satisfies me.

MM