"Long" 155s for the 308

[dwightlooi]

The newer 155s are so long they are as long as the 175 gr SMK. Should be a plus for everyone with a 10:1 barrel since stabilization has everything to do length and nothing to do with weight.



What are your experiences with them?

[crowbar]

The Sierra 2156 bullets work just fine at 800, 900, and 1,000 yards in my 13" twist Palma rifle. I have no experience with either the 2275 or the new TMK's.

[dwightlooi]

The Sierra 2156 bullets work just fine at 800, 900, and 1,000 yards in my 13" twist Palma rifle. I have no experience with either the 2275 or the new TMK's.

#2156 is simply a longer 155 with a more "hollow" nose. It is the highest BC 155 that still has a tangent ogive.

#7755 is a secant ogive bullet similar to the Berger VLDs and Lapua Scenars which also happen to have a plastic tip instead of a traditional open tip meplat.

The sharper nose profile of secant ogive designs have lower supersonic (wave) drag. However, the tangent ogive is more forgiving of chambers not cut to have the bullet "kiss" the lands as it has a far less abrupt rifling engagement event -- especially when you don;t have the best run out control. Some heavier secant designs also have a shank set so far back that the ogive extends to or below the case rim which makes crimping impossible.

They both work for me in a 20" 1:10 barrel. I am still working on the charge to get the best accuracy. Right now it is hovering at around 1MOA which is OK, but not great.

[kcstott]

you should see the 175 TMK's

[dwightlooi]

you should see the 175 TMK's

LOL! I bought a box and it was totally unusable. The ogive is so long it goes into the neck of the case. If you crimp it, the crimp goes on the sloped sides and pushes the bullet deeper.

I don't think you'll see commercially loaded ammo with the TMK for this reason.

[highpower790]

Take a look at Creedmoor Sports for commercially loaded ammunition using the TMK fwiw the TMK is over rated.

[dwightlooi]

Take a look at Creedmoor Sports for commercially loaded ammunition using the TMK fwiw the TMK is over rated.

Nah... they don't do the 175. There's the 168 and 155.

[OpenSightsOnly]

Nah... they don't do the 175. There's the 168 and 155.

The loaded ammo they sell is Lapua brass and 175 Scenars. If you have a bolt gun, that brass is good.

With Sierra's 2156, they were originally designed for Palma rifles.

Im sure they work well with your 20" and 1:10 but to take advantage of that bullet design you need a longer barrel so you can push that bullet around 2900+

For your 20" barrel with a 1:10, have you tried SMK 190s or Berger 185s around 2550 or 2600? That should get you to 1k if that is what you are after.

[dwightlooi]

The loaded ammo they sell is Lapua brass and 175 Scenars. If you have a bolt gun, that brass is good.

With Sierra's 2156, they were originally designed for Palma rifles.

Im sure they work well with your 20" and 1:10 but to take advantage of that bullet design you need a longer barrel so you can push that bullet around 2900+

For your 20" barrel with a 1:10, have you tried SMK 190s or Berger 185s around 2550 or 2600? That should get you to 1k if that is what you are after.

I get close... 51 gr of CFE223 with the #2156 gets me 2,892 fps avg (16 fps es). Haven't tried Bergers or the 190s. I did try the ELD-X 178s.