The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Ovenpaa wrote:Ignore my original post, I just realised I shot the original SMK 195 as opposed to the TMK's

Is/was there a SMK 195? I know of a 190.

Rox, I have 195 in my notes however I could be wrong, they came from you!

The venerable 190 and 200gn Sierra MKs are blunt, short-nosed and high-drag bullets by current design standards. Their downside is the resulting low relative BC, but the upsides of their configuration are being stabilised from slower twist barrels and excellent dynamic (as opposed to gyroscopic) balance making them very good extreme distance performers through transonic speeds and even as they fall through the speed of sound into subsonic flight.

The 190gn SMK has an OAL of 1.353". At 2,500 fps, Miller says that's an Sg of 1.39 in a 1:12" pitch and 1.65 in 1:11.

The 200gn gives very similar results at the same MV - 1.36 in 12 and 1.62 in 11 (both in 'standard' meteorological conditions). So, whilst losing a little BC, both will perform at 308 Win speeds in most conditions in the SAAMI standard 1:12 twist rate for the cartridge, and are fully stabilised in a 1:11 inch barrel.

I can back this with on-range experience having done a switch many years back from the 175gn SMK to 190 in a 24-inch 1:12" barrel rifle and seeing a big improvement at 1,000. (The 175 was marginally supersonic at this distance in many temperature conditions at the speed I was able to run it at, and I was almost certainly suffering from the very undesirable situation of one bullet being barely supersonic as it approached the frame and another falling through the sound barrier.) With a stiff Viht N550 loading maximising MVs the 190s would just have stayed supersonic as well as probably being a better performer in transonic speeds than the 175.

I think that, having read and now digested what people have indly taken the time to write here, I am going to shelve using the 195 TMK for now and try the 175 TMK instread.

My most recently load has been with the Berger 185 Jugs. These seem to group well at 100yds at least so hopefully I'll be able to test these properly at 900m next week.

Thanks again to all for the advice and suggestions.