Welcome guest, is this your first visit? Create Account now to join.
  • Login:

Welcome to the NZ Hunting and Shooting Forums.

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed.

Alpine Night Vision NZ


User Tag List

+ Reply to Thread
Page 3 of 4 FirstFirst 1234 LastLast
Results 31 to 45 of 51
Like Tree51Likes

Thread: The Maths of Recoil

  1. #31
    Member Puffin's Avatar
    Join Date
    May 2012
    Location
    Porirua
    Posts
    1,012
    Quote Originally Posted by grandpamac View Post
    Yes. Recoil increases in proportion to projectile mass but in proportion to the square of velocity. Those slugs are going a lot faster.
    Grandpamac.
    I'm not singling you out. I'm referring to comments like the above that are incorrect, because clearly it is the velocity of the projectile/s that are being referred to.
    grandpamac likes this.

  2. #32
    Member
    Join Date
    May 2018
    Location
    Porirua
    Posts
    1,336
    If Isaac Newton were to turn in his grave would he think about which way first?
    Moa Hunter, Cordite and grandpamac like this.
    Remember the 7 “P”s; Pryor Preparation Prevents Piss Poor Performance.

  3. #33
    Banned
    Join Date
    Mar 2015
    Location
    North Canterbury
    Posts
    5,462
    While we have recoil at one end of the firearm and the momentum of the projectile at the other, the effect of the projectile on game is not as simple as the amount of momentum nor is trajectory @Puffin. In my experience a sub sonic projectile with a given momentum will not kill as quickly as a high velocity smaller projectile with the same momentum despite laws of physics
    grandpamac likes this.

  4. #34
    Member
    Join Date
    Dec 2019
    Location
    Okawa Hawkes Bay
    Posts
    3,074
    Greetings All,
    My apologies to any who felt mislead by my posts. In retrospect I should have taken the time to get the differences between momentum and kinetic energy straight in my head before starting. The point of my posts was to, in general terms, show that the powder charge plays an important part in the recoil we feel and in answer to Micky's question why short barrel rifles boot more than longer barrel rifles with the same ballistics. I tried to keep away from formula to keep things simple to understand but did not do a particularly good job of that. Hopefully most of us have still learnt something in the process, I know that I have.
    Regards Grandpamac
    Moa Hunter likes this.

  5. #35
    Member
    Join Date
    Dec 2019
    Location
    Okawa Hawkes Bay
    Posts
    3,074
    Greetings All,
    On the subject of recoil I remembered a test done, years ago, to debunk the stories of deer being knocked flat by powerful modern rifles. The test was done using a wooden deer (a box filled with sand on three legs) and a .303 calibre rifle. Shots were fired into the box, from close range, and the amount the "deer" was rocked back by the impact recorded. It was not rocked back all that much. Placing the but of the rifle against the box and pinching the trigger against the trigger guard to fire it resulted in about twice as much movement of the "deer". This was likely published in Outdoor at the time and later in "The Sharp Shooter" published by Bruce Grant in the 70's. The original testing was done by Matt Grant ( Bruce's father) and others in 1947. We have not really come all that far have we?
    Regards Grandpamac.

  6. #36
    Member zimmer's Avatar
    Join Date
    Oct 2012
    Location
    Waikato
    Posts
    4,986
    @grandpamac
    Chapter 15 - Knocking Them Flat
    I'd post an image of the "deer" but photos aren't uploading lately.
    Micky Duck and grandpamac like this.

  7. #37
    Member
    Join Date
    Aug 2018
    Location
    Mayfield
    Posts
    43
    I think the shorter barrel length producing more recoil is also easily explained using Newtons second law, F=ma which is force = mass x acceleration.

    If mass (bullet weight) is constant and MV is the same across barrel lengths a short barrel will need greater acceleration to achieve the same MV as a long barrel. Hence, force increases with the increased acceleration of a short barrel which results in more recoil

    Sent from my SM-G975F using Tapatalk

  8. #38
    Member
    Join Date
    Dec 2019
    Location
    Okawa Hawkes Bay
    Posts
    3,074
    Quote Originally Posted by zimmer View Post
    @grandpamac
    Chapter 15 - Knocking Them Flat
    I'd post an image of the "deer" but photos aren't uploading lately.
    The Sharp Shooter is a great book. The chapters on killing shots on deer should be required reading today. I don't know how many deer Matt shot in his skin hunting days but it must have been heaps.
    Grandpamac.
    erniec, Micky Duck and Finnwolf like this.

  9. #39
    Member Micky Duck's Avatar
    Join Date
    Apr 2015
    Location
    Geraldine
    Posts
    24,822
    funny as heck..I was just reading thread and thought of that very thing ...then saw it in next post LOL.....didnt they do cricket ball thrown too...and it rocked "deer" more than projectile????

    one thing is for sure and for certain...the suppressor has changed the whole ball game COMPLETELY......and for the better too.
    I used to flinch...and down loaded my main rifle because of it..suppressed it.now she back up to full power/velocity and flinch...what flinch???
    Finnwolf and grandpamac like this.

  10. #40
    Member Ftx325's Avatar
    Join Date
    Jul 2020
    Location
    Nelson
    Posts
    3,128
    Quote Originally Posted by Moa Hunter View Post
    While we have recoil at one end of the firearm and the momentum of the projectile at the other, the effect of the projectile on game is not as simple as the amount of momentum nor is trajectory @Puffin. In my experience a sub sonic projectile with a given momentum will not kill as quickly as a high velocity smaller projectile with the same momentum despite laws of physics
    I think that's to do with the hydraulic shock more than anythy . Not sure on the science though but no doubt someone here will know.
    From my experience with my 338 lap mag and his 338 edge the science doesn't always work the way it should when it comes to PERCEIVED recoil.
    I have a lightweight Hardy 338 lap mag...carbon everything...around 4.5 kilo with scope and suppressor.
    The 338 edge has heavy stainless barrel, laminate wood stock, slightly longer barrel and muzzle brake and extra metal added to stock etc as runners as it's used solely for long range shooting and competition. Mine is a hunting rifle. He shoots 300gr versus my 250gr at near enough the same velocity. It must weight a good 2 or 3 kilos more than mine. On paper with all that extra weight and muzzle brake it should be significantly nicer than mine to shoot recoil wise. Hell no... I am happy to shoot mine all day but I won't shoot his using any limp excuse I can come up with.
    I think the brake alone is a large part of this. Again on paper it should be more effective at reducing felt recoil But in my opinion it increases Perceived recoil immensely. The blast noise is huge and with it blowing the scenery back in your face only increases the sensation. It also has a lot more solid butt pad. Mine is very spongey and absorbs a considerable amount of recoil. Also the blast noise is obviously significantly lower with the suppressor and it doesn't blow back at you which reduces the Perceived recoil considerably.
    So from my experience the math only tells half the story regarding actual recoil and perceived recoil. My lightweight 338 lap is a pleasure to shoot in comparison to his rifle but going by the math on paper it should be the other way around by a considerable margin.
    tikka, Moa Hunter and Micky Duck like this.
    born to hunt - forced to work

  11. #41
    Member
    Join Date
    May 2018
    Location
    Porirua
    Posts
    1,336
    Don’t forget get to add in trigger pull in your maths and finger weight.
    Remember the 7 “P”s; Pryor Preparation Prevents Piss Poor Performance.

  12. #42
    Member Ftx325's Avatar
    Join Date
    Jul 2020
    Location
    Nelson
    Posts
    3,128
    [QUOTE=Moa Hunter;. In my experience a sub sonic projectile with a given momentum will not kill as quickly as a high velocity smaller projectile with the same momentum despite laws of physics[/QUOTE]


    Ever tried a 45/70 shooting subs? They leave a pretty big hole and a quick death , especially using expanding rounds like the new Hornady offering.
    born to hunt - forced to work

  13. #43
    Member
    Join Date
    Jun 2012
    Location
    Blenhiem
    Posts
    1,108
    Quote Originally Posted by Moa Hunter View Post
    While we have recoil at one end of the firearm and the momentum of the projectile at the other, the effect of the projectile on game is not as simple as the amount of momentum nor is trajectory @Puffin. In my experience a sub sonic projectile with a given momentum will not kill as quickly as a high velocity smaller projectile with the same momentum despite laws of physics
    I shoot a lot of animals with 30 cal sub and projectile choice makes a huge difference in quickness of kills for example the Lehigh Defence controlled fracturing with its petals sharing off in multiple directions resulting in more damage and had a few instance bang flops with them on a hilar shot. Shot a red the other day and only went 15m on a broad side lung shot, they work a lot quicker than a standard mushroom design projectiles.
    Moa Hunter likes this.

  14. #44
    Member
    Join Date
    Jan 2018
    Location
    New Zealand
    Posts
    796
    Muzzle energy generally gives a pretty good indication of overall recoil. So if we take two identical rifles, but different calibres - the one with more muzzle energy should have more recoil.
    Now that's out of the way, the cartridges ability to rapidly accelerate the rifle (recoil) can be reduced by making the rifle heavier, and/or with the use of a muzzle brake.

    Now we have arrived at a base amount of recoil that is directly related to the muzzle energy and firearm weight, (with potentially a muzzle brake thrown in as a curve ball) - how that recoil is transferred to the shooter can be manipulated via stock design, fancy recoil pads and other technologies.

  15. #45
    Member SixtyTen's Avatar
    Join Date
    Dec 2015
    Location
    Auckland
    Posts
    535
    https://www.jbmballistics.com/cgi-bin/jbmrecoil-5.1.cgi

    I have spent a while playing around with this calculator, which has powder weight as one of the fields you enter.

    For example
    7Lb Rifle, 165gr projectile, 2800fps MV, 41gr charge = Recoil Velocity:13.5 ft/s Recoil Energy:19.9 ft-lbs Recoil Impulse:2.9 lb-s

    If you somehow managed to achieve the same MV with a 30gr charge (with all else being the same) your numbers would be: Recoil Velocity:12.5 ft/s Recoil Energy:16.9 ft-lbs Recoil Impulse:2.7 lb-s

    Not an insignificant difference.

 

 

Similar Threads

  1. recoil pad
    By jakewire in forum Shotgunning
    Replies: 4
    Last Post: 30-04-2019, 07:22 PM
  2. Recoil 270
    By Munsey in forum Shooting
    Replies: 21
    Last Post: 02-12-2016, 08:21 AM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Welcome to NZ Hunting and Shooting Forums! We see you're new here, or arn't logged in. Create an account, and Login for full access including our FREE BUY and SELL section Register NOW!!