175 SMK's for .308. And 168 SMK load questions

[4runnerman]

MetalGod What powder are you using to get 2700/fps with the 175's?.
I was 2.5 gns past max load with pressure issues just to get 2710/fps. Now I have a 24 inch barrel if that makes that much difference.

[Metal god]

I'm not , those are just numbers I thought would be max for the bullet weights shown . I did not want to say the 175s were 2620 and have somebody come in and saying , I get way more then that your numbers don't work for me . every load and rifle combo will be a little different . The chart above was just to show that you should be able to push the 155s faster therefore reducing wind drift .

My notes at a glance seem to tell me I loose or gain 100fps give or take with same powder charge per 10gr of bullet weight from 150gr to 190gr . Every rifle and Powder combo will be different . That's how I came up with those numbers in the chart . They are not confirmed velocities just guesstimates .

[HAMMER1DOWN]

The BC of the the 155 palmas may be really high for it's weight but that isn't going to keep the wind from playing them like fools at a distance. They still only weigh 155 while the 175's although slower will buck the wind better. Not to say I wouldn't try them if I don't end up liking the 175's. But from what I seen do far I think I might like the heavier bullets.
Now I hear of folks shooting the even heavier 180-190 SMK's, there is no way that my 1-12 twist would stabilize those is there?

[Metal god]

The 190s will be hard to stabilize in the temps your shooting in . You will get marginal stability at best . Shooting in 70* weather just barely stabilizes the 190s with a 1-12 according to Bergers Twist Rate Stability Calculator http://www.bergerbullets.com/products/target-bullets/ Top right of white page

190s are 1.36" / 175s are 1.23"

[HAMMER1DOWN]

I almost feel like I should just buy a 1/10 twist 28" tube and not have to worry about stabilization. That would solve a lot of problems.

[Bart B.]

I and others have shot many Sierra 180's and 190's from 1:12 twist 24 inch 308 barrels in cold weather. Accuracy averaged 4 inches at 600 yards, under 10 inches at 1000. Won matches with them, too.

Spinning bullets too fast makes those a bit too much unbalanced not shoot accurate. I'd not use a 1:10 twist .308 barrel for bullets lighter than 200 grains.

[HAMMER1DOWN]

It seems that all the knowledge I have gathered hence forth on barrel twist and bullet weight seems a little useless. I am gonna buy some heavy 180-190 grainers to try out and see what they do. Although I am sure that the velocities will be really slow. I'm sure that they will have one heck of a punch at range.

[Metal god]

All I'm going to say is , Bart is to me what E.F. Hutton is to every body else .

Please come back and let us know what velocities you get from the 190s . The best I'm getting with out pressure signs is 2400 or a little more . With 24" barrel

FWIW , I just happened to be looking at Bownells and they have the 155 palma and the 190s in stock right now .

[HAMMER1DOWN]

Temps here are going to start getting warmer again. We have been dealing with severe negative weathers this past week. -50 with the wind at times, guess we made national news too. But with the warmer temps I can get out and test loads and get velocities. I have been going stir crazy not being able to shoot. Trying to find some 190's and 155 palmas locally before I go online and buy them. I will keep you guys posted.