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I've been contemplating lightweight rifles. The downside being increased felt recoil. So the question is do efficient cartridges that achieve good velocity with smaller powder charges have less measured recoil than a cartridge burning more powder to achieve the same velocity ?
Newtons third law does not consider the rocket effect of burning gases or the weight of the gasses (propellant) that are also accelerated.
https://www.google.co.nz/url?sa=t&rc...FdNwGLZlwyk2Wx
my brain (& shoulder) associate more felt recoil with light weight rifle + heavier projectiles + pushing said projectile fast. Not sure that necessarily translates to more or less powder ? Different cartridges within similar case capacity for same calibre can produce quite different felt recoil from my expereince. eg 280 vs 284
Don't disagree with what you have written, but a cartridge that produces less recoil to start with for a given performance is going to end up better with the same good stock.Quote:
Originally Posted by Mauser308
A suppressor or a break divert gas and reduce the rocket effect of the burning / accelerating gas which we feel as recoil. So it is not just Newtons 'equal and opposite forces' at play
Greetings Moa Hunter,Quote:
Originally Posted by Moa Hunter
I've read in the past that the recoil generated by the powder gasses can be calculated by using the powder charge and a velocity of either 4,000 or 6,000 feet per second. I will try to find the reference. The rocket effect is included in this.
Grandpamac.
Greetings Again,Quote:
Originally Posted by grandpamac
I had a quick look through the formula you attached but to answer your main question Yes cartridges that produce the same velocity with less powder do produce less recoil. They do this, not due to some magic efficiency but due to less case volume. They also generate higher pressure. The rocket effect of the burning gasses is due to the mass of the powder charge and its velocity and nothing else. I see that the formula gives an approximation for powder gas velocity as 1.75 times projectile velocity. The formula should give you a raw figure for comparison assuming all else is equal which as we know seldom is.
I would ignore the section on metric units as it is outdated. Unfortunately Americans are profoundly ignorant on metrics and it often shows.
Regards Grandpamac.
I've wondered, now you can't have semi centrefires, would a straight skeleton stock arrangement built around a bicycle saddle spring stem give more pleasant recoil experience? Might even feel semi.
Attachment 147388
I found this link one day i was looking into it. It seems pretty similar for same bullet weight and speed to weight of the rifle. Its not a perfect table but it gives an indication.
https://www.chuckhawks.com/recoil_table.htm
From caliber to caliber i forgot to mention.
Yes I had firstly reached the same conclusion, the weight of the propellant being added to the projectile as what we are accelerating.Quote:
Originally Posted by grandpamac
The second conclusion being that if I am going to build a light carry rifle for the future it should be on a Kimber or small ring CZ action and chambered in 6.5 x 47 with a short barrel
It is interesting to consider the propellant and recoil impulse when comparing rifles. Some calibres just feel easier to shoot than others in the same weight of rifles with the same weight projectiles doing the same speed
NO Sorry @Cordite it wont work! Why you ask? Because she and hers will bring in a law where by you will have to wear lycra to shoot it.:sick:..and I aint doing that..:O_O:.leave the fish cakes out on the road ah.....(why fishcakes? cause thats what they look like after you hit one;)):thumbsup:Quote:
Originally Posted by Cordite
For one or two shots while out hunting i would not stress about how much you get beat up, can always use a slip on recoil pad when sighting in, Bit different if you decide to use it on a culling mission way more important aspects in a build
so a for example..150grn projectie going at 2500fps
we have many options to do it...
given same weight of rifle theoretically recoil SHOULD be the same.
the rocket gas effect.......now add in barrel length to equation a 30'' barrel which poked that 150grn projectile at 2500fps will have less blast than a 14'' barrel doing the same.....reguardless of amount of powder used BECAUSE it will be completely burnt before projectile exits.
Ive heard this same argument countless times with shotguns.....folks saying a 20ga recoils less than 12ga or vice versa...if both have 1 1/4oz payload and both weight 7lb..... if velocity is same so will be the recoil.
the ONLY other factor is amount of squeeze payload has when entering barrel.
biggest difference with top example is the noise will be further from ears so will seem less violent. longer barrels are definitely quieter, perceived recoil will be less even if measured felt recoil isnt.
The powder turns into gas which has the same mass so still produces recoil based on its mass and velocity. A rifle with an extra long barrel is nicer to shoot as the blast is less due to slower powder gas velocity but the projectile velocity will be higher giving more recoil. The rifle will also be heavier reducing the felt recoil. Also stock shape and fit has a massive effect on how we feel recoil. Along with the laws on conservation of energy there is one saying that matter can not be created or destroyed. It is merely changed to a different state. Enough theory for one day. 6th Form Physics never seemed so far back.Quote:
Originally Posted by Micky Duck
Regards Grandpamac.
I specifically kept velocity and projectile weight the same..... definately agree longer barrels are MUCH nicer to shoot.
You people make it hard - more bang juice= bigger bang = more recoil. Equation solved, now off to go find a life.......
Not the first time a 243 user has been referred to as a philistineQuote:
Originally Posted by 257weatherby
Is that you, @kotuku???Quote:
Originally Posted by Sideshow
An aside: why do 1oz 12g slug loads seem to kick harder than 11/4oz no.5 shot loads?
Higher velocity?
Greetings Micky Duck and others that may be interested,Quote:
Originally Posted by Micky Duck
Sorry Micky I had not answered your question so now, fortified with a night of slumber, a bowl of muesli and a large cup of tea, I will attempt to address it a bit better.
First I looked at the powder charge needed to produce the 2,500 fps velocity. The Hodgdon data for AR2208 and the .303 with the 150 grain projectile. Next I looked at velocity loss from the 24 inch test barrel to 14 inch. Using the lower end of the often quoted 20 to 25 fps per inch this works out to a loss of about 200 fps. The increase of velocity form 24 inches to 30 inches will be less so lets say a gain of 50 fps. AR2208 needs about 1 grain more powder to increase velocity by 50 fps in a 24 inch barrel so to achieve 2,500 fps the 14 inch barrel needs 44 grains, the 24 inch 40 grains and to 30 inch only 39 grains.
Now to recoil energy. The recoil generated by the projectile is the same for each barrel length. The velocity of the powder mass in high power rifles was given as 1.75 times projectile velocity. This is a rough average and the longer barrel will deliver less and the shorter one more. The formula for energy is 0.5 times mass times muzzle velocity squared so even the same powder charge will produce greater recoil in the shorter barrel than either of the longer barrels. The extra powder needed to achieve the same velocity in the shorter barrel makes this even worse.
So should we all ditch our shorty barrels and screw in 30 inch ones? Probably not. But we do need to remember that short barrels come at a cost, both velocity and recoil.
Regards Grandpamac.
That is a very clear way of explaining it GPM and would have Sir Isaac thinking. What interests me is if I am going to build a lightweight rifle in 6.5 mm that achieves 3000 fps with a 100 grain Barnes and have clean slate to start with, which calibre do I go with?. As an example only, I could go with a 6.5-284 and load it down or a 6.5 x 47 with a normal load. The 6.5 x 284 will need more powder and create more recoil to reach the same velocity with the 100 gr Barnes.Quote:
Originally Posted by grandpamac
Yes. Recoil increases in proportion to projectile mass but in proportion to the square of velocity. Those slugs are going a lot faster.Quote:
Originally Posted by Finnwolf
Grandpamac.
Greetings Moa Hunter,Quote:
Originally Posted by Moa Hunter
Thanks for your kind words. I suspect that other considerations will come well ahead of recoil in your choice but the 6.5-.284 Lapua loaded down will have a little more recoil than the 6.5 x 47 due to the increased powder charge. As you are building a lightweight rifle you may be looking at a short action which would rule the 6.5-.284 out. The curmudgeon in me would suggest that the 6.5 mm Creedmoor could be considered as well but that may not be what you are looking for. As I said other considerations.
Regards Grandpamac.
Quickload provides a recoil estimation based on the load you have plugged in at the time and the mass of the rifle. Don’t know how accurate it is but the numbers change in the direction you would expect if you alter relevant parameters. Felt recoil will be affected by stock design and fit as others point out.
Greetings Plinky,Quote:
Originally Posted by Plinky
Quickload has all the data needed to calculate recoil energy. They also have the ability to model a better figure for the recoil energy from the powder charge. The trick is how well they do it. Some of the Quickload data I have seen is dangerously hot especially with Barnes projectiles. It is just a matter of how good their model is. Still it will give you a rough comparison at worst.
Regards Grandpamac.
Timely to bring Chuck Hawks ( is there really a guy named such) in.
https://www.chuckhawks.com/rifle_recoil.htm
Check out his table. It's been around a long time. Does his info match QL calcs?
I'm a fan of QL but also treat some of its outcomes with scepticism......ah make that all outcomes until you have real world data to correlate.
I doubt it. Turning in his grave more likely. Recoil calculations are based on conservation of momentum.Quote:
Originally Posted by Moa Hunter
Quite Right Puffin,Quote:
Originally Posted by Puffin
Thanks for pointing that out. I shouldn't have mentioned the energy formula. I blame brain fade and the almost 50 years since sixth form physics. I was aware that the calculations for recoil were based on momentum but was trying to get the basic relationship between barrel length and recoil and why short barrels boot much more than longer ones for the same performance. Free recoil energy is still expressed in foot-pounds force or in metric Joules so introducing momentum, although correct, does not help basic understanding. I take no credit for disturbing Isaac Newtons slumber rotary or otherwise.
Regards Grandpamac.
I disagree. Basic understanding on recoil necessarily begins with balancing momentum.
The article the OP linked to contained all that was needed for him to answer his own question without being mislead.
I too disagree, I have not been mislead. Although the article contains all that I needed to answer the question opening the topic for discussion potentially has some benefit for other members. Newtons third does not allow for the propellant gas being diverted through a break or muffler from my understanding ?Quote:
Originally Posted by Puffin
It would seem difficult to do a straightforward calculation based on Newton's laws even with a normally crowned muzzle as some of the propellant gas will get vented at 90deg to the bore axis and will therefore not contribute to rearwards recoil. Some of the gas will exit at 90 degrees to the barrel, some at 45 degrees, some straight ahead, causing increasing rearwards recoil (rocket effect).Quote:
Originally Posted by Moa Hunter
Interestingly, a muzzle brake like on the Lee Enfield No 5 directed most of the escaping gases straight ahead (think rocket nozzle!) and increased recoil compared to without the flash hider. It was really not a flash hider but a blast forwarder, the figure I have for forward venting muzzle brakes is that they halve the sound hitting the shooter compared to a bare barrel.
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.Quote:
Originally Posted by grandpamac
If Isaac Newton were to turn in his grave would he think about which way first?
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
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
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.
@grandpamac
Chapter 15 - Knocking Them Flat
I'd post an image of the "deer" but photos aren't uploading lately.
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
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.Quote:
Originally Posted by zimmer
Grandpamac.
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???
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.Quote:
Originally Posted by Moa Hunter
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.
