loving 240gr sierra's in my 308 win

[Dimepuncher]

im shooting 240 gr sierras out of my savage 308 win at 2400 fps

240gr sierra
lapua cases
cci 200 primers
43.5 grains of rl-17
2.840 oal
2400+fps 26 inch barrel

tested these for accuracy this weekend ended up at 43.5 grains with a 5 shot group that measured .370 ;D and the first three shots were .100 so im pumped and the fit in my mag lol these bullets at 2400 have the same wind drift at 1000yrds as 208 amax at 2700 im just gona have to wait for the snow to go so i can see how the perform at longer ranges

 

[bugsplat]

If it works, use it. Thats a heavy bullet for 308 at those speeds. Is your barrel a 1-10 twist?

I love my savage rifles and have had the best of luck with their factory barrels. Best bang for your buck IMO. I have a model 12 in 223 that will shoot 40gr vmax bullets at 4300fps into .2 inch groups. I can then load up some 69gr SMK and shoot .3 inch groups at 2700. It will shoot everything I feed it. Someone forgot to tell it about barrel twist VS bullet weight when it left the factory.

 

[digrazir]

A 240 gr sierra does seem like an awfully heavy bullet for a 308. I was looking in my sierra loading guide which is admittedly a few years old and the 240 gr sierra was the heaviest bullet listed for both the 300 win mag and the 300 ultrta mag. The starting velocities were 2500 fts using 50 percent more powder in cases with much more capacity than a 308 case. I personally shoot the 175s and under in my 12 twist 308. I do however use the 250 gr sierra in my TRG 42 in 338 lapua. Thx Ray

 

[cmillard]

i would be willing to bet that after 400 yards the bullet becomes unstable and accuracy goes out the window. i am shooting the 240 out of my win mag but with a 9" twist (not needed in .300 win--going to rebarrel with 10" twist) but the velocity is significantly higher.

 

[Laurie]

I hate to rain on anybody's parade when they've found something that works for them Dimepuncher, so I hope the early promise is fulfilled when you can get more shooting in with the 240gn SMK. Like Cole, I do have some reservations as this is a wheel that has been invented many times before and has usually turned out to be less than round in extended usage.

Apart from Cole's almost certainly sound advice on stability, read up on Bryan Litz's views on .30 calibre match bullets. He states the 240gn SMK has too long a bearing surface length in relation to its nose and tail section lengths. This results in a poor BC value for the weight and excessive barrel copper fouling thanks to the large bullet-bore contact area. It was the latter feature that apparently killed this bullet in the days when .300 Magnums ruled long-range shooting.

I believe the new generation 210s are much more efficient bullets. The fact that UK and British Commonwealth Match Rifle (.308W at 1,100-1,500yd) shooters never used the 240, sticking instead to the 190 to 220gn SMKs and have mostly now shifted to the 210s tells you something. The shorter lighter bullets also allow slower rifling twists (1-11") and that means a slight increase in MV (less energy used in spinning the bullet up), every last few fps MV important to these competitors.

The other thing to watch is what Berger turns out in the coming months. It is a poorly kept secret that Bryan Litz is designing a complete new family of .308" bullets with the intention of achieving 'form factors' equivalent to the best of the 6.5 and 7mm designs. The thirty-cal equivalent of a 180gn 7mm will be in the 225-235gn weight range and should be an interesting bullet if and when it appears. It may revitalise .300 short magnums for competitive shooting. Whatever weight results in the step below (200-215gn) may be what .308W needs for some applications. Beware recoil and torque though from heavy bullets even in F/TR class rifles with big-foot bi-pods. It does degrade rifle/shooter performance - many British F/TR shooters are returning to 155s after dallying with 185-210gn weight bullets.

By the way, I'm also really sorry to have to tell you this, but your external ballistics figures are out. Bryan Litz's field tests (Applied Ballistics for Long Range Shooting as advertised on AccurateShooter) give the 208gn A-Max a G7 BC of 0.324, and the 240gn SMK 0.332. A 240gn bullet at 2,400 fps produces 3,070 ft/lbs ME (a good figure - I assume your Savage is a 30" barrel competition model to achieve this?) and it takes 2,578 fps MV for the 208gn bullet to match that value, so that should be achievable.

Berger Ballistics G7 ballistics program available with the above book or free from the company's website gives the following relevant values at 1,000yd for the pair:

208gn A-Max 0.324 G7 BC 2,578 fps MV = V1,000 of 1,381 fps W. Drift 1,000 of 75.02"
240gn SMK 0.332 G7 BC 2,400 fps MV = V1,000 of 1,276 fps; W. Drift 1,000 of 81.7"

both under standard environmental conditions.

Laurie,
York, England

 

[Dimepuncher]

i wouldn't doubt if they come unglued at longer ranges so ive come up with a load with 208 amax at 2700 shoots .5 moa 5 shots at 100 and i was going with published bc values i didnt realize litz rated the 240 so low i think this changes things thanks for the imput guys

 

[NORZ]

The only good use I found for the 240SMK in 308win was reforming the ogive to half sphere with a centerpunched hole in the process, end that was for subsonic use.

 

[rap36case]

You might try some moly in the barrel and coat the 240SMk. It will lower the pressures and gives me more consistent and lower SD on the velocity. The main reason to try the 240 is for wind out at 1000yards. The moly will help with barrel wear on a long bearing surface bullet, I imagine. If it works, please post some targets.

I like the 210SMk with moly at 2450fps. It is published in books by Brian Litz as a load out to 950 for game of 150LBs.

If all else fails, as Brian Litz via email. He might have run the experiment already.

 

[cmillard]

with the berger hybrids out, the 240 sierra could go by the wayside. the 200, 215 and 230 berger hybrids have shorter bearing surfaces and higher B.C.