.308 175 SMK over Varget

[tdavis757]

Hello all,

I am working through my first run ladder test and have come across a few obstacles. I ran 0.4 grain and then 0.3 grain increment ladder tests and narrowed the grouping tests to 43.9-44.5 grains. After shooting five shot groups I decided on 44.5 grains.

I was loading touching the lands at 2.2875 to the ogive during the tests.

Now that I settled on 44.5 grains I began working in seating depths from touching and working back 0.005 for five shot groupings. Now here's where I'm scratching my head...

As I backed off the lands I saw an increase in velocity (15 fps) with improvements in SD (6.5 at 0.02 jump). Is this normal?

Second question, I am getting an average velocity of 2715 fps out of a 22 inch barrel on 10 shot string (chrono was ~10 from muzzle). Generally speaking would you say this is a little hot out of a 22 inch barrel?

I appreciate any feedback or suggestions from you all.

 

[LNGRNG90]

I'm getting 2656 fps out of a 26" barrel with IMR 4895. As long as you don't have any pressure signs I'd say run it, and keep the velocity as high as possible.

 

[westcliffe01]

Your results for the SMK seem normal. They like a bit of jump. I loaded mine SAMI length and did not have to adjust the seating depth to get 1 hole groups. I can't find my load data, but I do recall that it was a compressed load. Compressed loads are always great for repeatability.

 

[Greyfox]

Of course this is rifle specific, but in the several 308 's I have owned, I'm usually at 42-43gr with Varget, IMR 4895, or R15 using the 175 SMK's for competitive work and loaded to an OAL of 2.81". This I'd pretty much the spec for Federal Gold Medal Match. Too much more powder has generally resulted in short brass life and loose primer pockets in my rifles. My loads produce 2600-2650 FPS out of my 24" barrels. You can use a grain or two more powder and keep pressures under control by seating the bullets further out, so you may not be at excessive pressure. The SMK's can take quite a bit of jump and still hold accuracy to sub .5MOA which is one of the attributes for keeping OAL sufficient for magazine feeding needed for some forms of competition.