Shotgun Knockdown Power Question

[Vapor Trail]

Will a slug fired from a semi-automatic platform, especially a lower-recoil model, have any less kinetic energy than an identical slug fired from a pump? Are any of the propellant gases taken away from pushing the round forward and used instead to cycle the next round/reduce recoil? I guess the two extremes I'm thinking of would be the Benelli Vinci and a Remington 870. Is one inherently more powerful than the other?

Thanks!

[SHIVAN]

Is one inherently more powerful than the other?

Doubtful there is a noticeable difference on target.

[MK18]

A gas operated shotgun will always have a lower velocity than a pump or recoil operated shotgun. This is why most semi autos will not run the reduced recoil rounds as there is not enough velocity or gasses to run the action. When you loose gasses, you loose velocity. The amount lost depends on the shotgun as some use more than others.

Typically the following muzzle and velocity readings are recorded from a single shot or pump action shotgun.

Federal TruBall Tactical Slugs Reduced Recoil
http://le.atk.com/ballistics/Ammo_Ba...ulletwgt=28.35

1642 ft/lbs Muzzle Energy

1275 ft/lbs @ 25 yrds

Federal Truball Full Power

http://le.atk.com/ballistics/Ammo_Ba...ulletwgt=28.35

2487 ft/lbs Muzzle Energy

1860 ft/lbs @ 25 yrds

Less velocity means less penetration. One must always remember that bullet placement is what decides the end effect of the bullet used, not the type or size. I would doubt the subject that received the slug would be able to argue with you which one hurt worse.

[thopkins22]

I'd wager that the velocity lost due to gas cycling the action is well within the margin of error on most chronographs.

[Univibe]

Let's do an experiment. Somebody out there needs to get an auto shotgun and a pump shotgun, both with 18 inch barrels, and chrono identical loads out of them. I'd do it and post the results, except I don't have a semi-auto shotgun.

I'm thinking there's not a measurable difference, but we need an experiment.

[MegademiC]

Will a slug fired from a semi-automatic platform, especially a lower-recoil model, have any less kinetic energy than an identical slug fired from a pump? Are any of the propellant gases taken away from pushing the round forward and used instead to cycle the next round/reduce recoil? I guess the two extremes I'm thinking of would be the Benelli Vinci and a Remington 870. Is one inherently more powerful than the other?

Thanks!

Yes, it will lower the muzzle velocity, which means less kinetic energy. However, kinetic energy means almost nothing when talking about wounding mechanisms.

IIRC, a 223 from same bbl length offered about 50fps difference between bolt and semi guns.

Bullet/slug design means infinitely more than velocity or energy.

[sl4mdaddy]

The notion of 'knockdown power' seems to be thrown about as a means of incorrectly describing the effectiveness of a particular caliber.

If a fired round were capable of knocking someone down or even off of their feet when hit, it would also have enough juice to knock the person firing the round on the ground as well. (ya' know, the whole equal/opposite action /reaction thing in physics...).

As previously intimated, bullet design and shot placement are a couple of the better concerns.