Grain Weight vs Felt Recoil

Discussion in 'Caliber Zone' started by buckeyedave, Feb 23, 2016.

  1. Does the grain weight have any affect on the felt recoil of a gun? ie; 9mm 115gr and 147 gr. Any difference in how it feels when you shoot it due to the weight of the bullet?

    A friend asked me that the other day and I didn;t know the answer so I thought I would ask you guys.

  2. missiledefender

    missiledefender Supporting Member

    Its all Physics. Equal and Opposite Effects.

    A 115 grain bullet is going to recoil LESS than a 147 gain bullet. Ever so slightly, that heavier bullet pushes back harder than a lighter bullet.

    So, if you have a shooter that is recoil sensitive. Go with lighter bullets.

  3. undeRGRound

    undeRGRound ROLL wif Da MOLE! Supporting Member

    Ummm, MD, most lighter bullets are loaded with MORE Powder,
    and have a higher listed MV and ME... I have not done enough
    consecutive back to back "weight changes" to really get a feel...
  4. planosteve

    planosteve Lifetime Supporter

    Only true if velocity is the same.
  5. mn_doggie

    mn_doggie Member

    I disagree. (Unless someone has tweaked the loads).

    I can load a mag with alternating Fed 115 gr and 147 gr. The 147 gr are definitely softer.
    Last edited: Feb 23, 2016
  6. greg_r

    greg_r Lifetime Supporter

    weight definitely has an impact on recoil.

    Will a 147 grain 9mm recoil harder than a 115 grain? It all depends. If everything is equal, yes. But what about powder weight? out of the same gun? Too many variables to give an honest answer.
  7. mn_doggie

    mn_doggie Member



    And velocity is rarely the same.

    It would take more powder to get a heavier bullet up to the same speed as the lighter bullet.

    If you want a 147 gr 9mm bullet to be travelling the same speed as a 115 gr, the pressure will probably be in the +p range.

    ME will be about 30% more so there has to be more recoil.

    Looking at commercially available loads, most standard 147 gr loads are running at 1000 fps or lower. 115 gr loads are running well over 1150 fps.
  8. Asher1

    Asher1 Member

    Don't forget load "recipes", powder burn rates will also have effect on recoil... same bullet, same FPS, can feel different if different powders are used...
  9. missiledefender

    missiledefender Supporting Member

    Newton's third law of motion: For every action there is an equal and opposite reaction.
    Combine this with Einstein's theory: e=mc²
    You can see the relationships.

    If everything else stays the same, an increase in weight/mass/grain = an increase in recoil.
  10. mn_doggie

    mn_doggie Member

    Perhaps you want E=m (V*V) where V= bullet velocity in this case.

    I've not seen any bullets travel at the speed of light yet.

    Correct, if everything else stays the same.

    The same powder load will not push a heavier bullet at the same speed.

    Here's from the article you quoted"

    Reloaders can often take advantage of these principles, allowing them to adjust where bullets hit from their fixed sight guns. Unfortunately, shooters relying on factory loads often cannot, since the ammo manufacturers usually load lighter bullets to higher velocity in a given cartridge. This is because commercial ammunition is loaded within specified pressure limits and most factory loads are close to maximum loads. A lighter bullet is typically factory loaded with more powder, and therefore to a higher muzzle velocity, than a heavier bullet loaded to the same maximum average pressure. Match ammunition and cowboy action loads are exceptions to this general rule

    Factory loads are usually run at max pressure listed for the type of load. (p, +p or +p+)

    If you are talking about hand loaded rounds then all bets are off. You can load stuff to +p++++ if you want and get any amount of recoil you want.
    Last edited: Feb 24, 2016
  11. lklawson

    lklawson Staff Member


    When trying to make a general guess at "felt recoil" (which is highly subjective), take a look at published Muzzle Energy.

    Peace favor your sword,
  12. missiledefender

    missiledefender Supporting Member

    Keep on reading, ya missed this part:

    A lighter bullet tends to decrease recoil, thus lowering the point of impact, but higher velocity flattens trajectory, decreasing bullet drop and raising the point of impact. Switching to a heavier bullet increases recoil, causing more muzzle flip and raising the point of impact, but the heavier bullet usually exits the muzzle at a lower velocity, increasing bullet drop, which lowers the point of impact in relation to the bore axis. The effects of bullet weight and velocity on point of impact are therefore opposed, making the net result of switching factory loads hard to predict.
  13. beaglenc

    beaglenc Member

    From my experience w/ commercially made rounds I agree with heavier grain, more recoil. I can alternate 185gr 45.acp and 230gr and I can feel the difference. Same in my snubbies in .38
    Now in long arms no doubt.
    150gr in '06(17# recoil) and 200gr is 20#+ of recoil.
  14. mn_doggie

    mn_doggie Member

    You are missing his point. He also says that commercial loaders tend to make lighter bullets run faster.

    Withing the first few paragraphs, Hawks says this:

    What are the practical implications of this? Here are some generalizations:
    1. A lighter bullet at the same velocity generates less recoil and thus less muzzle flip, lowering the point of impact.
    2. A heavier bullet at the same velocity generates more recoil and muzzle flip, raising the point of impact.
    Bullet weight is a major component of recoil, so these two statements make sense. Changing bullet weight while maintaining the same velocity is probably the most consistent way to raise or lower the point of impact, particularly if the powder charge can be kept the same, or at least very similar. (The amount of powder used, while usually not as important as bullet weight, contributes to the total ejecta upon which recoil is based.)

    Which is what I said because most commercial loaders load to pressure and that means that the larger bullet, tends to be run at a lower velocity.

    The Federal 147 gr loads I have fired thru the same pistol have a lower velocity than the 115 gr bullets. There is less felt recoil with the heavier bullets. I have, on more than one occaision, loaded a mag up for a newbie with twwo 115 gr and two 147 gr 9mm rounds. The person shooting, everytime, can tell which rund are lighter recoil. With the ammo I was using the lighter recoil always comes from the 147 gr bullets.

    Use the formula you gave. Energy, which is gonna indicate the amount recoil, is affected way more by the velocity. Lighter bullets generallyt travel faster. Pure physics.
  15. missiledefender

    missiledefender Supporting Member

    "Which is what I said because most commercial loaders load to pressure and that means that the larger bullet, tends to be run at a lower velocity."

    That's because the powder charge is the same in these Commercial Loadings.

    That is my point. Utilizing the same powder charge, same pistol/rifle platform and different bullet weights...the recoil will be different. Lighter bullets will recoil less and a heavier bullet (unless the Laws of Physics have been suspended) will recoil more. Because, the weight of the bullet and its Kinetic Energy/Push is transferred into the weapon and to the shooter.

    Once you start changing platforms and charge weights, things change.
  16. mn_doggie

    mn_doggie Member

    Are you saying that if the powder charges are the same, then the pressure would be the same? Will not the bigger bullet have a higher pressure because it takes up more space?
  17. missiledefender

    missiledefender Supporting Member

    Chamber pressure is going to be higher. The longer bullet will take up more case and raise the chamber pressure.

    What I'm saying is that if you loaded a: 95 grain 9mm bullet with .5 grains of Bullseye and another round with a 147 9mm bullet, same powder and charge, you will have a lower Recoil Impulse from the 95 grain bullet and a larger Recoil Impulse from the larger bullet.
    Last edited: Feb 24, 2016
  18. missiledefender

    missiledefender Supporting Member

    Chamber Pressure doesn't equate to recoil. Not with the came charge, in the same cal and brass.
  19. mn_doggie

    mn_doggie Member

    No. The heavier bullet will not reach as high a speed as the lighter bullet. Use the formula you quoted (but you can't use the "c").

    So if you take a 500 hp engine (think of it as the pressure, cuz in a bullet, it's the pressure that does the work), put in in a 2000 lb car or a 2500 lb car, in which vehicle will a passenger feel the acceleration more?

    The physics principles are the same.
    Last edited: Feb 24, 2016
  20. mn_doggie

    mn_doggie Member

    Indirectly it does affect recoil, because it is the chamber pressure that forces the bullet down the barrel. The higher the chamber pressure the faster the bullet will travel.

    Max chamber pressure for a 9mm is 35,000 psi (SAAMI spec). If two rounds are loaded to that spec, one being a 115 gr and the other a 147 gr, the lighter load will have a higher speed. The heavier load will have a slower speed. (fire both out of the same firearm so barrel etc isn't a factor.)

    I believe the heavier round, in this case will have less felt recoil, the total energy may be very similar, but the impulse will be wider.