300 blackout vs 308

[Borock]

I've done pistols and shorter rifles and want to get into shooting at distance (200+ yds). I don't want to shoot in competition, just the next step in my shooting. I have a 300 blackout upper with a nice scope which I've used at 185yds-easy squeezy. At 200 yds in perfect conditions (no wind, low humidity, etc.) how much of a difference in drop will I see between 300 blackout 150gr (16" barrel) and 308 147gr (24" barrel-my desired length)? I assume the velocity of the 308 is greater but is the difference a lot or a little that can be easily compensated with the scope adjustments? Thanks for any input.

 

[451_Detonics]

The 300 Whisper was developed primarily as a subsonic round using 200+ gr projectiles with a suppressor. Thanks to the smaller case capacity it was much easier to load to subsonic velocities while retaining excellent accuracy than the .308. I have been shooting both caliber suppressed since the 80's and the best .308 subsonic accuracy I obtained was with specialty low capacity brass that was very expensive, basically hand turned on a lathe.

Fast forward to a few years ago and the 300 Whisper copy appeared, the 300 Blackout. In supersonic loads it pretty much replicates rounds like the 7.62X39 and a few others but on the very reliable AR platform (just like my Whisper...lol). However in the same time period we had a great reduced power powder introduced in Trail Boss which was bulky enough it made loading .308 subsonic a breeze.

To me the 300 is a great 200 yard round, can be stretched out a bit further with light weight supersonic loads but long range is not what the round was designed for. It was made to hit very hard, very quietly at relatively close ranges. With a 150 grain you are looking at a max muzzle velocity under 2000 fps, a .308 with a 147 you are at 3000+
fps, quite a large difference.

This is going to make quite a difference in drop at longer ranges, without looking up ballistic charts I can't tell you exactly how much but it will be quite significant. There is a reason I own both calibers...different horses for different courses.

 

[Borock]

Thanks!

 

[Vespid_Wasp]

300 blackout is a completely different animal than 308, for a completely different niche. That niche is not longer range shooting.

You would be better served by a 308 in that role.

 

[shibumiseeker]

Something to keep in mind is that while the 300BLK will have more drop, it also flies differently. The .308 will be supersonic out to about 600-800 yards depending on bullet and load, and the 300BLK may not even start supersonic or if it does doesn't stay so very long (again based on bullet and load). Bullet design for subsonic is very different than bullet design for supersonic and can dramatically affect accuracy.

So it really is an apples and oranges comparison.

 

[avboiler11]

I don't understand the chosen bullet weights.

For 300BLK I'd be running 110-125gr supers as 150gr supers are slow and will result in much more drop, and for 308 I'd be running at least 168gr bullets instead of 147-149gr FMJs.

Assuming a 100yd zero, 500' ASL elevation, 59F temp and 0% humidity...a Hornady 110gr V-Max at 2375fps (listed velocity for factory ammo through 16" barrel) has a drop of 6.5" and a 10mph wind drift of 6.2". At 300 yards, that goes to 23.3" drop and 14.8" wind drift.

A 308 pushing a 168gr Amax @ 2600fps has a 200yd drop of 4.5" and drift of 3.3"; at 300yd you see 16.0" drop and 7.6" wind drift.

For punching paper or banging steel, drop is pretty insignificant but the wind drift difference is substantial; only you can decide if that matters or not.

 

[Hohn]

IMO, heavier bullets, even at greater drops, are advisable. They tend to do better in the wind, and have higher BCs, sometimes a lot higher.

This is not always the case, though. In some cartridges, the decrease in velocity is too significant compared to gains from heavier bullets. 300blk isn't real fast to start with.

 

[youngda9]

Go put in the variables and figure it out. Handloads.Com Ballistic Calculator You can learn a lot for yourself if you experiment with the variables to see how much of a difference they make at various ranges.
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