Subsonic centerfire accuracy vs. Caliber

[libertyman777]

I've been reading some and see that there can be some accuracy issues with the larger centerfire rounds when shooting subsonic.

Which centerfire caliber is proving to be the most accurate when staying subsonic? What distances?

Thanks,

Paul

[Spook]

Paul, You ask a "loaded" question :grin:. I've been fooling around with a .338 X 39 round in a very tight twist, that is shooting Very :eek: accurately with both 250 and 300 grain bullets'
The 510 whisper is no slouch when using Amax bullets and I've heard good things about Lehigh bullets in both 50 and 458 caliber.
This should generate a lot of argument, but I'll go out on a limb and say equipment and smithing matter a Lot more than caliber.

[Rikky Lee]

Agree - once you have the load right there are one hole groups out there just waiting to be had with subs. No recoil allows some good technique to be developed.

[HUNTER2]

Shooting .510, 357, 45 cau., 300 whisper sub.... Agree with them. With the right load - I can see no difference in acc.. They all are more capable than the nut behind the bolt! Differences in recoil and terminal damage naturally...........

[LouBoyd]

What sort of accuracy do you want and at what range?

I'd rather have a subsonic rifle which can shoot 6" groups at 600 yards than one which can shoot 1/4" groups at 100 yards even though the first is only 1 MOA and the latter is 1/4 MOA accuracy. In the first the shots aren't likely to be touching. The later is a one hole group.

The time of flight of the 600 yard rifle with be more than six times longer for any cartrige/bullet than for the 100 yard rifle. It's vertical drop will be more than 36 times greater than the 100 yard rifle. And its sensitivity in vertical dispersion to muzzle velocity variation will be more than 36 times greater than for the 100 yard rifle. It's a much more difficult rifle to build and the ammo will require much greater care to achieve the require velocity uniformity. The wind deflection of the 600 yard rifle will be much more than six times that of the 100 yard rifle, the actual amont depends on the bullet's drag.

The 100 yard rifle would favor a relatively small bore rifle shooting moderately heavy low drag bullets which are known to stabilize easily, probably in the 150 to 200 grain range. The 600 yard rifle would favor whatever bullet has the highest BC. Probably one of the 400+ caliber bronze solids with a BC greater than 1.1. Bullet stabilty is not likely to hurt accuracy more than vertical dispersion. It would also need a small case capacity and a high pressure rating to give the most uniform muzzle velocity.

All of that is just based on calculated ballistics. As Spook said the gunsmithing of a particular rifle can make one better or worse than another. That's also true of the quality and consistancy of the ammo.

[libertyman777]

You guys are talking way over my head on this one. Through more reading, I believe what was at issue was ensuring that a proper twist rate was used to stabilize the round in rifles that are normally shot supersonic. I can see by your responses that once this is taken into consideration, subsonic shooting is the way to go.

I'm not sure about distances. What would be considered a max distance to take a deer sized animal cleanly? (200-250 yards?)

The reason this so appeals to me is that I already shoot a type of suppressed, subsonic rifle in a PCP air rifle. Compared to .22 rimfire, the considerations listed are valid and apply (longer time of flight, vertical dispersion, etc.).

Paul

[Rikky Lee]

Again - not a simple question to answer as it relates to your hunting situation and the size of the deer and the depth of your wallet.

I would say for a 200 yard deer rifle - noting that most hunting shots are taken within 80 - 120 yards - I would recommend a 300 Whisper or a 338 Whisper type round with my preference going to 338 (based on my experience to date with the subsonic 30BR).