Recoil & Bullet Weight

asd9055

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There's the physics of recoil, and then there's perception. Geometry of the rifle/stock combination can make a world of difference in perceived recoil.
+/- 3/4" difference in LOP from your ideal fit can turn a rifle into something downright painful to shoot.
I learned that from a 270 (painful) vs. a 7 Rem Mag (shoot 2 boxes, NP). Now I only own rifles that "fit" me.
Totally agree. Felt recoil can be affected so much by fit and the way a rifle is held. You can get bruised by a bad fitting 270 and not by a great fitting and correctly held 375H&H
 

johnzor

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Another big factor is how much your rifle weighs. If it's a hunting rig then lightweight is fine for a few shots if you can tolerate it.
Not that you would notice in a hunting situation.
My 300 RUM tossing 230 Bergers at 3000 fps is 8 3/4 pounds with a muzzle brake and still kicks like ****.
 

Bravo 4

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Another big factor is how much your rifle weighs. If it's a hunting rig then lightweight is fine for a few shots if you can tolerate it.
Not that you would notice in a hunting situation.
My 300 RUM tossing 230 Bergers at 3000 fps is 8 3/4 pounds with a muzzle brake and still kicks like ****.
What brake do you have?
 

Jon Bischof

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There is more than one way to mitigate felt recoil. Putting a Limbsaver recoil pad on your rifle will affect the felt recoil more than changing the bullet weight. And if you already have a good load worked up with the heavier bullet, then with a Limbsaver, perhaps you don't need or want to go to a lighter bullet.
 

DJ Fergus

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I'm shooting a 338 Edge with a 300 grn Berger. I also shoot a 300 RUM. Both rifles are similar in build and weight including having the same brakes. I'm shooting 199 grn Hammer Hunters in the RUM. The difference in recoil is night and day between the two.

My question is, how much bullet weight would I have to drop to start noticing a reduction in recoil with the Edge?
In my old 300 win mag, I shot a 180 gr aprx 3200fps. I shoot a 180 in a 7mm STW aprx 3200 fps. While the recoil impulse is just a little different, perceived recoil is pretty much the same. In the 30 cal rifles, a 208gr was very noticable compared to a 230gr. Stepping up from a 230 to a 245 was noticable. My educated guess is that dropping to a 250gr in the 338 would be enough for you to be content with it's recoil.
 

Jon Bischof

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Pads & stock design make for comfort. I have 1 inch Pachmayr Decelerator pads on some of my rifles. The energy might be the same but the discomfort is less.
Absolutely! The first time I experienced the effect of a Limbsaver pad was many years ago on my Benelli SBE 3.5" Turkey loads with HeavyShot. Kicked like the business end of a Jackhammer with factory pad. Harder than most LRH rifles. After Limbsaver, I dont don't even think about recoil anymore and I still shoot the same 3.5 Heavyshot artillery load.
 

jdavistx

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Here is the math formula:


Factors like rifle weight, bullet weight, powder charge weight, & velocity affect recoil. The end result being F.R.E. = 1/2MV**2. The 32.17 is the acceleration in feet per second per second of a falling object. This is divided into the weight of the rifle to get M, the physics guys refer to this value as "slugs". I am at a total loss of how this calculation runs out with a brake screwed onto a muzzle and the same load fired thru the barrel.
Need to know.

F=MA. The brake reduces F by some amount. Mass is the rifle. Acceleration is essentially recoil. 32.17 is the acceleration due to gravity in fps. Assuming the rifle direction is roughly perpendicular to the direction of the gravitational force it has no net effect on F (recoil). It is what makes a rifle weigh, or causes bullets to drop after fired but has no effect on recoil.
 

ButterBean

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There's the physics of recoil, and then there's perception. Geometry of the rifle/stock combination can make a world of difference in perceived recoil.
+/- 3/4" difference in LOP from your ideal fit can turn a rifle into something downright painful to shoot.
I learned that from a 270 (painful) vs. a 7 Rem Mag (shoot 2 boxes, NP). Now I only own rifles that "fit" me.

F=MA. The brake reduces F by some amount. Mass is the rifle. Acceleration is essentially recoil. 32.17 is the acceleration due to gravity in fps. Assuming the rifle direction is roughly perpendicular to the direction of the gravitational force it has no net effect on F (recoil). It is what makes a rifle weigh, or causes bullets to drop after fired but has no effect on recoil.
That's all fascinating but the OP's question is
" My question is, how much bullet weight would I have to drop to start noticing a reduction in recoil with the Edge?"
 

Paladin300

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I have read the above responses and I would agree with some of the comments about stock design and fit. I have owned several 375 H&Hs over the years. I have never been able to freebore one until I bought my Sako 85. It is the lightest 375 I have ever owned and has no break on it. I don’t know that it recoils less but there is less felt recoil because of the the way the gun recoils straight back into the pocket of the shoulder. Fit and Finnish of a stock matter. A stock that does not fit you will drastically amplify recoil.

As to the question of the Edge versus the RUM recoil I am perplexed? If they are similar guns they should recoil similarly. There is not that much difference in the cartridges. I have a 338 RUM with a slightly improved chamber and an elongated throat. It pushes 300 grain OTM Bergers at 2775 with 91 grains of H1000 (3150 ftlbs). It pushes 265 grain ABLRs at 3000 with 96 grains of H1000 (3295 ftlbs). The noticeable recoil between the two is not significant. This is primarily due to energy which is what causes recoil. If you go down in weight but up in velocity the initial energy will be similar to the heavier projectile going slower.

Everyone is different in how they handle recoil but a good brake makes all the difference in the world. I am running an APA FB Gen 3 on my 338 and we push 60+ rounds through it on a regular basis with no issues. I have a APA LB Gen 2 on a 300 WM and you can’t tell the difference between it and a 6.5 Manbun we are running. APA builds some great breaks that can even help improve accuracy somewhat. Both my 338 and 300 shoot 1/2 moa or better. I prefer the APA LB Gen 2 without the adjustable ports on top.

In summary, I would check the fit of the stock and possibly look at a different one (stock shape matters) or getting it better fitted to you and I would try a different brake. Bullet weight will not make that much difference if you intend to get the best performance out of it.
 

jdavistx

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Here is the math formula:


Factors like rifle weight, bullet weight, powder charge weight, & velocity affect recoil. The end result being F.R.E. = 1/2MV**2. The 32.17 is the acceleration in feet per second per second of a falling object. This is divided into the weight of the rifle to get M, the physics guys refer to this value as "slugs". I am at a total loss of how this calculation runs out with a brake screwed onto a muzzle and the same load fired thru the barrel.
Need to know.

F=MA. The brake reduces F (force) by some amount. Mass is the rifle. Acceleration is "recoil." The problem with your analysis is that gravity is operating roughly perpendicular to the direction of the rifle and therefore has no effect on recoil. Think of gravity in terms of vectors or the direction of the force. Trigonometry says the cosine of 90˚ is zero.

As you have correctly stated E=1/2MV**2. Where:
E= energy
M=mass
V=velocity.
Some wonder why reducing the mass of the bullet doesn't reduce recoil by the same amount. That's because when velocity increases it's by a squared value.
 

Hugnot

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Sep 26, 2020
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Montana
I messed around with Open Office & came up with a spread sheet:

Screenshot (235).png


My biggest is a .375-.338, smallest is a .20 P - see trees on the sky line or exploding rodents.

I don't have either a .338 Edge or a .300 RUM so I had to get into the Hodgdon Load Data Site to guesstimate.
Continuing on with:

" My question is, how much bullet weight would I have to drop to start noticing a reduction in recoil with the Edge?"
Screenshot (236).png


Bullet weight was reduced to 225 grains & velocity upped to 3000 - just guessing - pain & expense to get into this stuff.

Another wild guess is the gas velocity, saw somewhere they used 5,200 ft/sec as gas would gush out in front of bullet.

The acceleration of gravity, 32 ft/sec ft/sec is used to derive the mass of an object in "slugs". This assumes the operation is being performed on the face of this planet. The kinetic energy formula is E = 1/2 M V ^2 (1/2 Mass * Velocity squared). Physics guys use "slugs' to figure out kinetic energy. Mass in "slugs" = weight in pounds divided by 32.17

Explanation of slug (not snail like creature):


I have a Magneto Speed chrony and should I use it with a heavy recoil rifle I would wrap 2 layers of duct tape around barrel with 1/4 sticky side up to keep the rifle from backing away from the the chrony.
 
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