Would a lower pressure result in less felt recoil?


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Nowhere Man
January 19, 2010, 08:14 AM
I'm looking at new (to me) .45acp loads. 200gr LSWC. 4.8 of TG results in 13,400 CUP vs. 4.3 of Clays results in 17,000 cup.

Does the load pressure have any relationship with felt recoil?


Thanks,

Dave

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rfwobbly
January 19, 2010, 08:36 AM
Not necessarily. I can't compare the exact loads here at work, but IMHO, with all things relatively the same, felt recoil is more often a result of powder burn rates. It's like saying which hurts more: getting hit by a home-run swing with a baseball bat, or getting hit by a Caterpillar D8 bulldozer moving at 1 foot per minute. There's far more power in the bulldozer, but at that speed you simply end up being "pushed" and not "hit".

Gadzooks Mike
January 19, 2010, 08:42 AM
The pressure doesn't make any difference, but the acceleration (speed) does. The recoil (force) you feel is mass times acceleration. Pressure plays a part in how fast you can sling the bullet out of the barrel, but it's still the acceleration and mass that will be used to calculate recoil. Oh, and of course, the mass of the gun as well. It's accelerating in the oposite direction (recoil).

Walkalong
January 19, 2010, 08:46 AM
The pressure curve vs bullet weight will have more affect on recoil, than just pressure alone.

For those two powders burn rates, which are similar, I would not excpect to see any recoil difference from pressure differences, only velocity differences.

243winxb
January 19, 2010, 10:43 AM
Muzzle energy = bullet weight X fps.

Jim Watson
January 19, 2010, 11:08 AM
Sorry, 243, but that is Power Factor, which is momentum in non-standard units; not energy.

As to the OP, it depends on whether you are as sensitive as The Princess And The Pea.
Some people say they can tell a difference in such things, and go into discussion of acceleration rates. I can't.

I might notice a muzzle blast effect, higher chamber pressure leads to higher muzzle pressure leads to louder blast. Which accentuates recoil. I was chronographing 9mm the other day and while Blazer was only slightly faster than S&B, it was a lot louder and had a perception of greater kick; although the computed recoil was only 3.5% more.

RandyP
January 19, 2010, 12:07 PM
The pistol ergonomics and specs make a huge difference in perceived recoil too. My P3AT makes for a very 'snappy' aggressive shooter while my Springer GI feels more like a comfortable 'push'.

rcmodel
January 19, 2010, 12:23 PM
4.8 Titegroup = 877 FPS. 4.3 Clays = 888 FPS.

2 1/2 pound gun:
Recoil Impulse in (lbs sec) = .86 ---- .86

Velocity of recoiling firearm (fps) = 11.12 ---- 11.13

Free recoil energy in (ft/lbs) = 4.80 ---- 4.81

The slightly heavier powder ejecta of the Titegroup load offsets the 11 FPS lower velocity.

I'd say it's a wash!
But as noted, it may "feel" slightly different.
Or not.

rc

Nowhere Man
January 19, 2010, 01:21 PM
Thanks guys. :)


Dave

SlamFire1
January 19, 2010, 05:05 PM
Cut the momentum and you might feel it.

Momentum = mass time velocity.

Only momentum is conserved in collisons.

I can feel the difference between 200 grain bullets and 230's in the 45 ACP. And I know cutting the velocity to 720 fps from 800 fps really reduces felt recoil.

Walkalong
January 19, 2010, 06:35 PM
Yep. Cutting bullet weight can do it, assuming you don't make it up in velocity, and even then, equal, by numbers, recoil will feel different.

Nowhere Man
January 19, 2010, 08:37 PM
I'm looking at a load for IDPA CDP Class. I'm looking at a power floor of 165,000. 165,000 / 200gr = 825 f/s min.

I should be able to do it with either TG or Clays. That's when I noticed the differences in load pressures.


Dave

avan47
January 19, 2010, 10:07 PM
In rifles,yes. In the situation you cited, probaboy not noticable. The mass of the powder charge and its exit velocity after the bullet leaves the barrel is part of the recoil equation. Higher pressure means higher exit velocity of the burned powder gas. Magnum rifles with higher powder charges and higher chamber pressures kick harder than non magnum rifles. In the case you cited, the mass of powder is much less than the mass of the bullet. A lighter bullet, 200gt vs 230 gr or 185 gr vs 230 gr would have more effect in reducing recoil.

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