Bullet weight vs. Recoil

[TonyDedo]

After 5 or so years of using moly coated lead 230 RN bullets in my XD45, I've finally exhausted my supply of components and I'm looking to restock. I want to get back into IDPA, and maybe even dabble in USPSA, so I need to take power factor into consideration when I work up my next load. For years I've had people (especially the IDPA guys) telling me I should shoot 200gr instead of 230gr bullets - conventional wisdom is that 200gr bullets will have less recoil, less muzzle rise, and I'll be quicker back on target.

Makes sense to me, at face value. Given that 200gr bullets are less expensive, it may even behoove me to switch to 200gr.

Then I start doing my research, and it seems this is actually a controversial topic - half of the internet thinks a heavier bullet will produce more recoil (less mass creates less force pushing back), the other half thinks it will produce less (slower speed, and some theory about the bullet pushing the gun back and not up).

So I start thinking about the physics involved. Now mind you, I'm an accounting and finance guy, the sciences were never my strong suit, but it seems to me that the force is the variable we should be concerned with, not mass. If I'm developing loads with the same power factor (a rough measurement of force), no matter the weight of the bullet, the force will be the same, thus recoil should be the same. Right?

I.E. a 230gr bullet with the muzzle velocity of 717fps should have the same recoil as a 200gr bullet at 825fps, because they're both have the same power factor.

Am I barking up the right tree here?

So really if I'm looking at this from an economic standpoint, my only concern should be how much more powder it takes to propel a 200gr bullet to 825fps vs a 230gr bullet to 717fps. If it's not significant, I can get the same power factor and same recoil using lighter bullets that cost about 1.5 cents a round less.

I have a few 200gr bullets kicking around, and I'm going to try to do a comparison based solely on perceived recoil, but I wanted to form a solid hypothesis first. Also I don't have a chrony yet (or enough 200gr rounds to build up a load to the right velocity), so I can't be sure both rounds are generating the same power factor.

Anyway, thanks for the help!

 

[ETXhiker]

This is an interesting topic. It seems very counter-intuitive, but (at least with 9mm) a lighter bullet seems snappier than a heavy one. I have mostly loaded 230 gr. in .45 ACP, so I'm not sure in that caliber. In a nine, a 115 gr. seems snappier than a 124 gr., and the 124 seems to recoil more than a 147. Maybe it is a matter of recoil velocity, rather than energy? The funny thing is, that anyone who shoots rifles will tell you that the heavier the bullet, the heavier the recoil. Can anyone explain why pistols would be different?

 

[Andrew Leigh]

Tell me what powder you plan on using and the total mass of the handgun and barrel length.

Early calc's would indicate that the 200gr bullets given the speeds you quote will actually have more recoil @ 6.34ft/lbs. With the same powder a 230gr. will need 1gr. less powder to reach 717fps and will deliver 6.05ft/lbs

 

[Buck13]

If I remember the physics right, momentum is conserved, kinetic energy is NOT. So, the momentum of the recoiling gun must equal that of the bullet. Power factor is the same as momentum (mass x velocity) so two rounds of the same PF should have the same recoil. (Two rounds with the same KE would not have the same recoil. The heavier bullet would have more momentum and recoil.)

However, the powder ejecta has recoil, too! So, a lighter bullet using more powder is going to have more mass of ejecta, and that gas is going to be moving faster at the instant the bullet clears the barrel. The muzzle pressure is going to be higher too (not the same as peak pressure for the charge, that happens when the bullet is still near the case), which means that the gas in the barrel is going to stream out past the bullet faster as the bullet clears the barrel, i.e. the gas accelerates even more to get out of the barrel with the higher charge, so the gas for the lighter bullet has both more mass and more velocity. I have NO idea how to calculate this difference. I'm sure it's real, but I'm not sure it's significant.

 

[Mad Chemist]

It's been a while since I studied physics, but I would expect that felt recoil has more to do with jerk than with force. Jerk is the derivative of acceleration. Basically, the acceleration of acceleration.

So if we were comparing 2 equal energy totals, but one total was composed of a heavier mass projectile pushed by a smaller charge while the other was a lighter projectile pushed by a larger charge, it is reasonable to expect that a the d/dx of acceleration would be greater for the lighter projectile. This is reasonable since the lighter projectile must accelerate more quickly and therefore the rate of change of its acceleration must be greater as well.

It's been a long time since I solved derivatives and I don't use much higher math at work. Maybe we have an engineer on the board who could chime in and correct my premise?




As far as 200 vs 230gr goes, I doubt that it makes a substantial difference in felt recoil by switching between 200 and 230gr projectiles. I think the real reason most competitive shooters do this is for practicality. 200gr bullets are cheaper and can still easily make major PF.

 

[Mad Chemist]

Buck,

The mass of gas escaping will be less than mass of the powder since combustion will never be perfect. Some residue must remain in the weapon, otherwise I'd never have to clean my guns Since the difference in powder charge mass for a typical .45acp load at 200 vs 230 with the same powder is usually only a fraction of a grain, I doubt that the mass of the ejected gas and particulate is significant.

 

[TonyDedo]

Shooting a Springfield XDM 5.25" barrel (32oz unloaded). My 230gr load is 5.3gr of Unique - I haven't built up a load for the 200gr bullet yet, but I'll be using the same powder.

 

[35 Whelen]

I didn't read all the posts, but something that's rarely if ever mentioned when discussing recoil is recoil velocity. Buck13 whether he realized it or not, described it perfectly. It's a snappy feeling recoil, as opposed to the almost slow rise of the muzzle when using heavier bullets instead of light.

When my wife and her girlfriends started practicing here at the house to qualify for their CHL's they all came out with their little 9mm's and none of them could hit worth a flip with them and complained about the recoil. So I hie off to the safe and retrieved my Colt Gov't Model 45 ACP and a box of handloaded 200 gr. SWC's. They all shot much better and were better able to deal with the slow roll type recoil of the 45 than the snappy, bite-type recoil of the 9mm's.

I've never fired any of those run and gun handgun competitions, but I can see where loads with less muzzle flip/recoil would be desirable.
35W

 

[Andrew Leigh]

Shooting a Springfield XDM 5.25" barrel (32oz unloaded). My 230gr load is 5.3gr of Unique - I haven't built up a load for the 200gr bullet yet, but I'll be using the same powder.

Hi,

I have used QuickLOAD to simulate.

5.3gr. of Unique with a 230gr. Hornady FMJ will give 815fps providing the COL is 1.275". This equates to 13 643psi which is well within the 21 000psi SAAMI limit so a nice safe load. The recoil calculates out at 7.77ft/lbs. This is a very appropriate load.

If you popped a 200gr. Hornady FMJ and you loaded to the SAME pressure to give roughly the same given recoil.

6.3gr. of Unique with a 200gr. Hornady FMJ will give 914fps providing the COL is 1.275". This equates to 13 616psi which is stilll well within the 21 000psi SAAMI limit so a nice safe load. The recoil calculates out at 7.74ft/lbs. This is an appropriate load, however 6.2gr. would be better.

So your recoil range with a 200gr. moving down the charge scale from 6.3 to 5.3 would move from 7.74ft/lbs to 5.53ft/lbs and the velocity would drop to 775fps.

An interesting number that QuickLOAD pops out is the "Muzzle Pressure" which in the case of the 230gr. is 2 437psi lifting to 2 957psi with the 200gr. load. I would read it to mean increased muzzle lift for the lighter bullet based on my experience.

I had the same on a rifle, a .375H&H. While shooting essentiall the same pressure loads one day but with two different powders I noticed that the muzzle lift was excessive and required additional measures to hold the rifle adequately to restain the recoil. My shooting buddy also remarked on the visible difference he could see. The groups were also worse until I learnt to hold on tigher. When we checked QL we were vindicated, the loads that bucked the most had the higher Muzzle Pressure.

Hope this helps.

 

[Grumulkin]

After 5 or so years of using moly coated lead 230 RN bullets in my XD45, I've finally exhausted my supply of components and I'm looking to restock. I want to get back into IDPA, and maybe even dabble in USPSA, so I need to take power factor into consideration when I work up my next load. For years I've had people (especially the IDPA guys) telling me I should shoot 200gr instead of 230gr bullets - conventional wisdom is that 200gr bullets will have less recoil, less muzzle rise, and I'll be quicker back on target.

1. I doubt you'll notice much of a difference in the above scenario.

2. Felt recoil will depend on the mass of the combustibles, the mass of the bullet, the time over which acceleration occurs and the velocity acheived.

 

[Reloadron]

SAAMI has a brief white paper on the subject which can be seen here.

There are also several web based calculators out there for what they may or may not be worth. The SAAMI link explains things pretty well. The Wikipedia also covers the subject using the same formula as the SAAMI paper.

Ron

Ron

 

[LiveLife]

After 5 or so years of using moly coated lead 230 RN bullets in my XD45, I've finally exhausted my supply of components and I'm looking to restock. I want to get back into IDPA, and maybe even dabble in USPSA, so I need to take power factor into consideration when I work up my next load.

For years I've had people (especially the IDPA guys) telling me I should shoot 200gr instead of 230gr bullets - conventional wisdom is that 200gr bullets will have less recoil, less muzzle rise, and I'll be quicker back on target.

230 gr vs 200 gr felt recoil and muzzle flip also depends on the powder burn rate used and amount of powder charge (mid range vs high range load data).

This is for match shooting.

Not sure about IDPA but for USPSA, once we identified the caliber, power factor requirement, bullet weight and powder/charge that chrono's at a few PF above minimum, then we adjusted recoil spring rate that produced the desired/comfortable felt recoil/muzzle flip.

My vote is for 200 gr load that produces the most accurate shot groups with recoil spring rate that allows you to shoot fastest with greatest comfort level as match stage time often trumps slightly greater accuracy.

 

[oneounceload]

Recoil is a factor of gun weight, ejecta weight (powder bullet, etc.) and velocity. There are numerous internet recoil calculators where you plug in a few numbers and it gives you the recoil. Recoil does NOT increase in a linear fashion either.

Using this one:
http://www.handloads.com/calc/recoil.asp

with the following data from Hodgdon
200 grain bullet, max load of 5.4 grains of Titegroup, velocity of 957fps compared to a
230 grain bullet, max load of 4.8 grains of Titegroup, velocity of 855fps gave the following results:

Recoil Impulse in lbs.sec:
200 bullet is 0.94; 230 is .096
Velocity of recoiling firearm in fps:
200 is 13.83; 230 is 14.01
Free Recoil in ft/lbs:
200 is 6.54; 230 is 6.71

so the lighter bullet will have less recoil.

This was using lead SWC bullets and assuming a constant gun weight of 2.2#

 

[abq87120]

Conventional wisdom on recoil is to load a heavy bullet with hot powder. And be careful.

 

[fiftybmg]

I've reloaded 200gr CMJ and 230gr CMJ in a .45 ACP for IDPA some years ago, and at the time it seemed to me the lighter bullet produced greater felt recoil.

The true test would be to shoot a classifier with both and check the score difference.