This has been discussed on a hunting forum I frequent, and I wanted to see if there are any varying opinions one way or the other to my query.

You have two different 45-70 loads, both are loaded to a MV of 1800fps. One round is using a 300gr bullet, the other uses a 405 gr bullet. Seeing that both are loaded to a MV of 1800 fps, which round will create the most ftlbs of felt recoil and why?

Doc,

my guess would be that the 405 grain bullet would have more recoil. It would take a bigger powder load to get a 405 grain bullet moving at 1800 fps than it would a 300 grain. More powder means more energy which means more kick. This is all assuming that you are using the same powder, primers, etc.

Theoretically, wouldn't it recoil with about 33% more force?

The 405 is going to have a lot more kinetic energy, so I'm guessing the 405.

The 405.

It required more force to move a heavier bullet at the same speed.

405 at 1800 fps wouldn't be fun.

http://www.chuckhawks.com/358Win_mystery.htm

"The .45-70 is another very popular cartridge. A 300 grain bullet launched at 1800 fps from an 8 pound rifle generates 22.5 foot-pounds of recoil. The 405 grain bullet at 1330 fps generates around 22.8 foot-pounds. These are the standard low pressure loads. With hotter loads for modern high strength rifles, the .45-70 will push a 350 grain bullet at 2100 fps, providing 36.4 foot-pounds of recoil from an 8 pound rifle."

It's going to take quite a bit to get that 405 moving 1800 fps.

The 405 grainer at 1800 fps, generates 46 ft-lbs of energy.

We have one old guy on our hunting forums that thinks the 300gr is much more punishing than the 405 when loaded to 1800 fps and that physics does not apply when shooting this gun.

He claims the 300gr has violent kick and the 405 just pushes. Yeah, a 405 at 1800fps with puch your a$$ right into the ground.

Even when given proof of lab testing, he refuses to believe the 405's are more punishing at the same velocity.

Doc,
Don't you know?
Physics does not apply in really old man world.

Thanks, but we do know the effects of gravity!

Ask that old man what will hit the ground first. A bullet shot from a gun, or a bullet dropped from the same height.


That should be a good way to dis-credit him in front of everyone on that forum.

Given the same velocity, the 405 grain bullet generates more recoil than the 300 grain by a long shot.

Are you sure that the original hunting forum question didn't ask which normal factory load (300 grain bullet @ 1800 fps or 405 grain at 1300 fps) doesn't recoil more? The answer to that questions is a little more debatable.

The only way you can get the .45-70 405 grain bullet to 1800 fps is to handload or use one of the semi-custom ammo manufacturers. That bullet weight at that speed is a serious load.

[This message has been edited by Doubtful (edited 12/4/2009 5:17p).]

for every action there is an equal and opposite reaction...

E = 1/2mv²

double m, double E
double v, quadruple E

The 300 at 1800(24) will have a greater recoil than the 405 @ 1330(19).

Neither is all that much....I think you will find that the 300 @ 1800(24) is about like a 300WSM.

The 405 is about like a middle of the road 30-06(20).

Suck it up....

If you change the bullet weight of the 300@1800 and keep everything else the same it will be 405/300=35% higher....300 Ultra mag type...you are getting there.

I assume you are talking about free recoil as opposed to felt recoil.

[This message has been edited by sunchaser (edited 12/5/2009 7:10a).]

Ok, here's some drunk math. The units will not be correct, but I'm not going to try to convert the bullet weights to Kgs or convert the fps to meters per second.


The 300 grain bullet at 1800 fps will create 486,000,000 units of energy.

The 405 grain bullet at 1330 fps will create 358,202,250 units of energy.


Throw out whatever units I just created, but the 300 grain bullet traveling at 1800 fps will deliver 1.35 times the amount of energy as the 405 grain bullet traveling at 1330 fps.


Sunchaser, you're on to something here.

Remington "Core-Lokt" SP:
405gr @ 1330fps

405gr = 0.057857142857 lbm

E = (1/64.4)(0.0579 lbm)(1330 fps)² = 1589.2 ft-lb

Remington "Core-Lokt" JHP
300gr @ 1810fps:

300gr = 0.042857142857 lbm

E = (1/64.4)(0.0429 lbm)(1810 fps)² = 2180.2 ft-lb

Hornady LeveRevolution
325gr @ 2050fps:

325gr = 0.046428571429 lbm

E = (1/64.4)(0.0464 lbm)(2050 fps)² = 3029.8 ft-lbs

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Sunchaser, you're on to something here.

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Don't be giving him credit on a public forum!!

He's arrogant enough as it is...

yo guys missed that they are both loaded to 1800FPS....

1330 FPS was the original load of 405, not what was being tested.

Yeah, rerun the numbers at 1800 fps. That 405 goes up a lot.

I don't think they missed it, I think we all agreed that the 405 at 1800 is much greater.

...I just think that they took it upon themselves to expand the discussion. This is TexAgs afterall.

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and that physics does not apply when...

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physics always applies.

I don't think I missed doodly squat unless Doc was asking a dumb question as to whether or not a heavier bullet creates a greater recoil than a lighter one with every thing else being equal.

You know like if I shoot a bowling ball at 1800fps is the recoil going to be greater than, less than or equal too a basketball at the same 1800fps.....everything else being the same?

Basketball is a leather imitation girls.

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He's arrogant enough as it is...

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My my.....It's hard to believe the change in a person that a slumpbuster from CS and one deer that AC passed on can have on one individual.

405 factory load SP at the standing position is not too bad-more like the rolling "push" others described.

Same load sitting at a bench rest put an ouchie on my collarbone.

Never said I wasn't arrogant, just that you were too.

...not my fault AC was "holding out for a big one."

quote:

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Ask that old man what will hit the ground first. A bullet shot from a gun, or a bullet dropped from the same height

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....or you.
There is one and only one scenairo where they hit at the same time and an infinite number where they don't.

quote:

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There is one and only one scenairo where they hit at the same time and an infinite number where they don't.

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You get my point though.

I know what you are trying to say but what you said is incorrect.

[This message has been edited by sunchaser (edited 12/5/2009 1:30p).]

what happens if we dimple the jacket...like a golf ball?

just shoot it already ! we can use them here in mississippi as a muzzleloader and i have sited in 3 in 1 day using both the 405 gr and the 325 ballistic tips and yeah my shoulder was a little sore the next day but not enough to worry about. chalk it up to a day of dove hunting w/ a 12 gauge. but hunting with it and shooting it 1 time is less than a 3 1/2 12 gauge turkey load. just MHO. great brush gun.

Sorry, I am not asking a dumb question, just stating that another old hunter thinks that a 405 loaded to 1800fps has less felt recoil than a 300gr loaded to 1800fps.

The only recommendation I could give him was that he needed to make sure his shooting range is upwind of the meth lab.

Every thing else the same....it's a significant difference....So much that if you were at a shooting range you would never ever be able to convince any one willing to shoot both. I believe you could get a group of bystanders and they would be able to pick the heavier round just by watching his reaction from each shot.