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I was doing the math to confirm drops for .308 subs tonight, based on 200 grain bullets at 1050fps.

I think I will need around 6.5MOA over my normal 100m zero to get to 100m followed by 23MOA for 200m and 41MOA for 300 yards, I should run out of elevation at 320m with my S&B PMII

Has anyone any experience with .308 subs and drops to confirm this or similar?

Have you got the correct subsonic BC for your bullet?

I saw a sub .308 question on accurate shooter, have you searched their forum?

DM

dromia wrote:Have you got the correct subsonic BC for your bullet?

I have a G7 of .235 from the Lapua site. I made a mistake by calculating for a 220 when it should be a 200 bullet (Lapua 4 PL 7060) so my drops now show:

6.4MOA @100y
21.8MOA @200y
38.6MOA @300y

So I should be able to get to 350 yards.

DM - I will take a look at Accurate shooter as well

That is the subsonic BC?

Your BC increases as the velocity drops and most HV bullet BCs are calculated on the basis of the super sonic velocity that the round is designed for. Starting with a subsonic velocity challenges the existing BCs of most HV bullets.

Thats why the whisper family is such a conundrum of a round it turns conventional ballistic thinking on its head, a slow heavy bullet shouldn't do what it does.

Of course the BPCR buffalo hunters of 130 year ago understood this perfectly.

There is nothing new under the sun.

You're stretching my memory, it's been a while since I've shot any subsonics.

I was using a red dot with a 5 MOA dot. At 200m I was resting the bottom of the dot on the top of the Fig 11 for centre of mass hits.

From memory I zeroed @ 100m which gave a hold over of 15MOA which was 3 dots as described above.

Going back over my notes a 50m zero required 4 dots (20MOA)@ 200m which is why :-P I went for the 100m zero.

168 gn A-Max @1080fps.

That is the BC Lapua quote for the bullet which is designed for subsonic work

http://www.lapua.com/en/products/reload ... bullets/15

It seems odd to me as well, in fact I could not make up my mind how the bullet would perform, also the spread sheet shows a surprisingly low velocity loss out to 300 despite the MOA required. All very odd and a new world to me.

Yup,

I posted on the original guntrader site (before censorship) as i got all anal about using my steyr ssg69 in 308 with moderator to stalk deer in a forest, near a housing estate. Anyway, i got such conflicting advice that i went ahead and reloaded some using some yank recipes and some modified 300 whisper data.

Bullet drop was like the proverbial lead balloon with my scope (Kahles 7x42) running out of 'clicks' beyond 300'ish yards. It was very weird to shoot though with minimum recoil and very little sound from the T8 moderator. Mates standing nearby said it sounded like a springer air rifle.

Unfortunately the excessive bullet drop - requiring significant re-dialing of the scope if the deer were only 50yds further/closer and the unpredictable effects from gusting winds made it to much of a pain to stalk with.

Playing Devil's Advocate here, but would those loads be legal under the "Deer Act".

I don't have the figures to hand.

I'm not implying that you are not cabable of killing deer cleanly, at sensible range, with accurate shot placement, but there are minimum energy levels, in Law.

Please don't take umbrage!

Regards,

Daz

For me it is merely out of curiosity and the fact that I have a rifle with a large moderator on the end. It will be interesting to hear how quiet a rifle really is.