Cast boolits = less recoil than jacketed?

[troy_mclure]

Cast boolits = less recoil than jacketed? Or is it just in my head?
I was shooting the same load(200gr @ 2000fps) out of my .35 rem chambered marlin 336(over a chrony). And it felt like the cast boolits had a bit less recoil to them.
The loads were identicle except the bullet/boolit.

Is it just in my head? :veryconfu

[xacex]

Less friction=less recoil. From what I have read in this forum, and what I learned in college physics what you experienced is normal with cast loads. The pressure required to push a lubed lead bullet down the barrel is less than the pressure required to push that same weight bullet that is jacketed. That pressure increase directly correlates to the recoil you feel as the bullet leaves the barrel. There is a formula for the coefficient of friction between lead, and copper in relation to weight of the bullet, and speed which will tell you the amount of recoil you feel. I remember seeing one in a lyman reloading manual, but I cant remember it it took the coefficient of friction into account. Take the same bullet and molly coat it, and the recoil will be even lower. As I recall, you need that pressure to attain velocity out of the muzzle so your feet per second may be a bit slower.
xacex

[btroj]

Bullet type shouldn't matter one hoot. At least not enough to really be noticeable.

Recoil is largely based upon the mass and velocity of the bullet, and powder gasses, leaving the barrel acting upon the mass of the gun. The gun is pushed in the opposite direction.

Friction may play a role in the elocity developed by the bullet but shouldn't make any real difference in felt recoil. The fact we can get a similar velocity from a cast bullet with a smaller powder charge can make a slight difference in recoil.m thisis because we reduced the mass of the powder gasses leaving the barrel.

Since your load was "identical" other than bullet type I would say it was "all in your head", or shoulder rather. You perceived a difference and that is all the matters. Some guns, or loads, just feel like they recoil more. Whether or not they do isn't the key, it is all in what we perceive.

[Echo]

Muzzle velocity and ejecta mass are the determinates of recoil...

[popper]

Walt Disney said equal and opposite action/reaction.

[canyon-ghost]

This is just my thought, different recoil. A jacketed has muzzle climb, lead bullet pushes straight back. Therefore, it isn't necessarily less, just different. It also takes less powder with a lead bullet to seal the bore (in that instance, less recoil is correct).

[tomme boy]

You have to add the weight of the powder with the weight of the bullet to make it equal.

[MT Gianni]

In the 45-70 and the 35 Whelen with heavy bullets the answer is " it doesn't feel that way to me". A 311284 @ 2400 fps will push you around a bit also.

[xacex]

Muzzle velocity and ejecta mass are the determinates of recoil...

But don't forget the compression force that is involved that creates the increase on pressure, and muzzle velocity. I may have made a mistake with the friction coefficient( lead has a higher friction coefficient with steel than copper does), but we all know copper is harder than lead. The compression force is created when the bullet enters the barrel and is swagged down. I tried to come up with a formula today, but the barrel length, and twist would be possible factors as well...and I just got tired of looking at it. I think the difference would need to be at least a foot pound of force to be perceived on your shoulder however.

good luck with your experiment.

xacex

[MtGun44]

Lead has a much lower coefficient of friction with steel than copper, NOT the other
way around. Actually, lubricated tin-lead alloy on smooth steel has been used in all
large machinery for centuries because it has very low friction. Look up babbited
bearings.

Why do you think that engine bearings are made with a surface of tin-lead alloy, not
copper? Many have a copper layer deeper down to conduct heat away, but never
on the surface.

On low speed bearings, BRONZE is used but it still has higher friction than tin-lead, but
can be lubed with grease where tin-lead needs to be cooled with pumped oil flow,
so only used inside engines and similar locations.

Bill

[felix]

The shape of the acceleration curve as well as the absolute values of the pressure along the curve must be computed as a composite to obtain the muzzle velocity. We must compute the energy displaced to the shoulder vector only, assuming upwards lift of the muzzle does not contribute to felt recoil. At any rate, when you get down to it, the velocity of the ejecta has zero bearing on the energy (mathematically so) applied to the shoulder. ... felix

[troy_mclure]

Well it's from a micro groove marlin 336 in .35rem if that maters any.

[xacex]

Lead has a much lower coefficient of friction with steel than copper, NOT the other
way around. Actually, lubricated tin-lead alloy on smooth steel has been used in all
large machinery for centuries because it has very low friction. Look up babbited
bearings.

Why do you think that engine bearings are made with a surface of tin-lead alloy, not
copper? Many have a copper layer deeper down to conduct heat away, but never
on the surface.

On low speed bearings, BRONZE is used but it still has higher friction than tin-lead, but
can be lubed with grease where tin-lead needs to be cooled with pumped oil flow,
so only used inside engines and similar locations.

Bill

That is what I thought as well. However, when I looked at the chart it gave me a higher coefficient of friction for lead with steel than copper. It didn't make sense to me this morning, and it still doesn't. That is why I started to look at other factors to why the pressure curve would be different. That is where the swaging down of the bullet, and compression force came into play. With a 35 Remington it is quite possible to get a 1f/lb difference of recoil quite easy irregardless of bullet type if you are not careful with seating depth or powder charge. I am not saying that is a hallmark for sensitivity to recoil because everyone perception of recoil is different. I probably couldn't feel the difference of one pound myself.
I think felix is on the right track. You may need to tweak the formula with the reduction of friction if felix lube is involved. That stuff rocks! Thanks man!
xacex

[Catshooter]

Well, this is an area that I don't know much of, but I'll say this: part of the recoil forces is also made up of the resistance the projectile to spin. I have read that that is why when the M-1 tank main gun went to a smooth bore they could take of the muzzle brake. The recoil was much reduced.


Cat

[felix]

Yep, the bigger the diameter of the projectile, the more energy it takes to overcome the rotational inertia! One big reason to slow the twist (if possible) for range intended. I've seen figures approaching 30 percent of expended energy in doing so. I don't remember the caliber of gun discussed. Naval guns? Perhaps. ... felix

[1Shirt]

Lite loads, lite recoil! Heavy loads, heavy recoil! Seems like common sense to me!
1Shirt!

[David2011]

You can do the math all day long but IMO, based on field experience, all that really matters is how fast the projectile is moving and how much it weighs including the weight of the gunpowder. Everything else is little details. My .22-250 has an 8" twist rate but with the little 50 grain .224 bullets it's more of a roll component than any real additonal recoil.

I can't feel any difference between a 230 grain cast boolit and a 230 grain jacketed at the same velocity out of my 1911s. Ditto for the .44 Mag. Same weight; it FEELS about the same. My cast .44s thump me a little harder because they weigh 255 grains where the commercial jacketed is 240. Both are smoking out the 14" barrel of a Contender at 1600 fps so they both have significant recoil and cease to be fun after 5 or 10 rounds due to the trigger guard tang hitting the back of my left index finger. I'm considering a reinforced glove for my supporting (left) hand. The recoil doesn't bother my shooting (right) hand; it's just that trigger guard tang that hurts.

David