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Thread: Recoil difference between similar loads?

  1. #1

    Default Recoil difference between similar loads?

    I wanted to get the opinion of some of the experienced guys on here regarding some loads a friend has been developing.

    He is comparing these to factory loads and finding a significant recoil difference between the two.

    All loads are fired from the same gun.

    Projectile weights are either the same or no more than 5gr. difference (they are not the same projectiles).

    Muzzle velocities are the same within normal deviation ranges.

    Felt recoil is as much as 40% less in his loads compared to some of the factory loads.

    What are the contributing factors that would be causing this? Recoil velocity related to powder burn rate is all I could think of.

    What do you guys think?

  2. #2

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    Speculation about his loads compared with factory loads? I'd give better than even odds that the factory loads use a heavier charge of slower powder to achieve the same vels. One of my favorite powders is IMR-3031. That's because I use it so much in moderate loads. Drop charges of a slow powder to reduce velocities 200-300 fps in average cases, or load enough 3031 to get the same velocity, and you'll feel a whole lot less recoil using the 3031.

    I don't recall the formula at the moment, but powder weight has a surprising affect on recoil. It's easiest to see and mess with using loose powders in muzzleloaders, because you're doing your "reloading" right there at the shooting bench. Vary the charges up and down the scale and use faster and slower powders. I can guarantee that using 120 grains of black powder to move a 400 grain conical to the same velocity you get with a 45-70 using perhaps 40 grains of smokeless powder will dot your eye and cross your tee. Even a much heavier muzzleloader makes a Marlin guide gun seem like a gentle kitten.

  3. #3

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    Quote Originally Posted by BrownBear View Post
    Speculation about his loads compared with factory loads? I'd give better than even odds that the factory loads use a heavier charge of slower powder to achieve the same vels. One of my favorite powders is IMR-3031. That's because I use it so much in moderate loads. Drop charges of a slow powder to reduce velocities 200-300 fps in average cases, or load enough 3031 to get the same velocity, and you'll feel a whole lot less recoil using the 3031.

    I don't recall the formula at the moment, but powder weight has a surprising affect on recoil. It's easiest to see and mess with using loose powders in muzzleloaders, because you're doing your "reloading" right there at the shooting bench. Vary the charges up and down the scale and use faster and slower powders. I can guarantee that using 120 grains of black powder to move a 400 grain conical to the same velocity you get with a 45-70 using perhaps 40 grains of smokeless powder will dot your eye and cross your tee. Even a much heavier muzzleloader makes a Marlin guide gun seem like a gentle kitten.
    That's about what we were thinking, as he is using a very fast powder AA#2. But that makes me wonder why the factory ammo companies don't do the same thing both for the decreased recoil and for the economy of smaller charge weights. Are the slower powders somehow inherently safer?

  4. #4

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    Quote Originally Posted by evandailey View Post
    That's about what we were thinking, as he is using a very fast powder AA#2. But that makes me wonder why the factory ammo companies don't do the same thing both for the decreased recoil and for the economy of smaller charge weights. Are the slower powders somehow inherently safer?
    I bet that's exactly how they load their "managed recoil" rounds, or whatever they're called. As for why use the slow? They're trying to squeeze every last fps from their ammo in a velocity-crazed market. No marketing edge if you're even 50 fps slower than your neighbor, and in fact there will be guys everywhere crying that they wouldn't shoot that brand of ammo because it is "so slow," or because they can beat factory with handloads. Kind of a catch 22 for the companies I bet, needing to make more money for the corporation that owns them and their shareholders.

    Another very good reason on the long list of reasons to be a reloader. Get what you want and what works best for you.

  5. #5
    Moderator Paul H's Avatar
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    I don't know how to measure fealt recoil, but in two rifles I have personally experienced signifigant differences in recoil. Don't use these loads, they are probably wrong, just off the top of my head.

    Rifle A, 350 rigby built on a VZ-24 action, 24" barrel. Load 1 250 hornady, 66gr Varget, 2700 fps at the chrony, load 2, 250 hornady, 72 gr H-4350, 2700 fps at the chrony. The recoil was night and day, the Varget load was pretty much straight back and tollerable, the 4350 load had the rifle rotating much more and the cheek piece on the stock was slapping my face hard, no slap from the varget load.

    Rifle B, 458 lott, p-14 enfield, 22" barrel. Load 1 500 gr hornady, 87 gr RL15, 2280 fps at the chrony, load 2 500 gr hornady, 92 gr VVN550, 2200 fps at the chrony. Load 1 was heavy recoiling by tollerable, load 2 could be quantified as, hmmm, can't believe I lost nearly 100 fps, because this thing is kicking the living snot out of me.

    I don't know why the slower powders seem to recoil more, but in the medium and larger bore rifles, you can deffinately feel a noticeable increase in recoil that calculated recoil levels would never show you.
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    Supporting Member iofthetaiga's Avatar
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    Quote Originally Posted by Paul H View Post
    I don't know how to measure fealt recoil, but in two rifles I have personally experienced signifigant differences in recoil....I don't know why the slower powders seem to recoil more, but in the medium and larger bore rifles, you can deffinately feel a noticeable increase in recoil that calculated recoil levels would never show you.
    I'm never going to claim to be a rocket scientist (not even while engaging in the act of reloading; at that time I think it more accurate to describe me as a rocket elementary student), so the following is only a semi-intuitive guess. Obviousely there are many, many variables at play and we will likely never know definitively what causes differences in felt recoil. I'm guessing however that powder burn rate plays a significant role by influencing the shape of the pressure curve. I'm guessing that in turn has a direct correlation to acceleration (thrust). Then we apply Newtons Law about equal and opposite action, and acceleration dictates (actual) recoil. Then felt recoil is influenced by an almost infinite number of variables including but not limited to the weight, length, shape of the gun and stock; physical properties of the recoil pad; size, weight, muscular and skeketal properties of the shooter; variations in placement and firmness of how the stock is held against the shoulder, etc, etc, etc. Am I way off the mark?
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    Supporting Member iofthetaiga's Avatar
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    I think the OP was on track with his original speculation. I think that if we were able to actually measure felt recoil, we could execute a test wherein we use the same rifle, cartridge, projectile and primer. Loading to achieve the same muzzle velocity with powders of progressively varying burn rate, I suspect the resulting felt recoil results would plot as a bell curve.
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  8. #8

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    Quote Originally Posted by iofthetaiga View Post
    I'm never going to claim to be a rocket scientist (not even while engaging in the act of reloading; at that time I think it more accurate to describe me as a rocket elementary student), so the following is only a semi-intuitive guess. Obviousely there are many, many variables at play and we will likely never know definitively what causes differences in felt recoil. I'm guessing however that powder burn rate plays a significant role by influencing the shape of the pressure curve. I'm guessing that in turn has a direct correlation to acceleration (thrust).
    Iofthetaiga may be onto something: thrust.
    It's not just the weight of the bullet and powder that is involved here, but also the effect of thrust caused by powder gas exiting the muzzle, and the velocity of that exiting gas. I would think that slower burning powder would have more pressure at the exact moment the bullet exits the muzzle, therefore more speed of the exiting powder gas.
    Just a theory...

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  9. #9

    Smile

    If you read up on hornady super performance ammo thats just what they explane in detail. Comparing their light magnum which has all the powder you can stuff in the case they get increase in both velocity and recoil do to the jet effect of the muzzle blast. While with their new powder blends specific to each cartridge the get a flatter pressure cruve for increased velocity while decreaseing jet effect muzzle blast thus less recoil.

    I fingured that out with the light magnum 270win ammo it did have signifacant more recoil than did any 150gr ammo I have shot in my rifle. While slower more effecient cartridges did have lesser felt recoil even thou they had 200-225gr bullets example 358win and the 35 whelen.

  10. #10
    Member akgun&ammo's Avatar
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    I think I would trust a good cronygraph more than guessimates of recoil. You may find the lower recoil is slower too. There are many variables we take in stride when we develope good and accurate loads for our firearms. Sometimes, recoil just has to be addressed- Like when I load up my 416's.. the 325 gr bullets sure feel worse than the 400's.

    Not enough info to truly answer evandailey's question though. What rifle? What barrel length? What type of bullets? What Types of prepreration of cases in the reloading process? and so on, and so forth...


    Chris

  11. #11

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    We have deduced it is the "rocket" effect of the gas leaving the barrel with the slower powder in the factory loads that is causing the recoil difference, which is what Brownbear said and what we suspected. The particular instance I was referencing this time was between two different .40 S&W loads one factory and one in development. They were both being fired in the same 4.5" 1911. Like I said, velocities were identical, and projectile weights were within 5 gr. The handloads were using a much faster powder than the factory load, thus the reduced thrust from the gasses leaving the barrel.

  12. #12
    Member akgun&ammo's Avatar
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    The variable of the speed of slide since using a 1911 style pistol could change the felt recoil.

    Chris

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