Is there any correlation between chamber pressure and felt recoil? If so, is there a formula for figuring the recoil? I apologize in advance if this has already been discussed. I tried the search and came up with nothing relevant.
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Re: Chamber pressure and recoil?
JBM Recoil Calculator
Notice that chamber pressure is not one of the inputs.....
JBM Recoil Calculator
Notice that chamber pressure is not one of the inputs.....
Re: Chamber pressure and recoil?
This is a reloading forum, where people often think about peak pressure, so as to not damage the brass, primer, or gun.
The muzzle velocity is integral of pressure times distance minus friction.
The instantaneous recoil and instantaneous recoil are tightly related, but the felt recoil comes through the averaging filter of soft human flesh and gun mass.
The peak pressure's affect on the brass, primer, and gun are also time averaged, but with a faster time constant than than the bullet reaching the muzzle.
Generally things in the time domain are hard to get an intuitive feel for.
This is a reloading forum, where people often think about peak pressure, so as to not damage the brass, primer, or gun.
The muzzle velocity is integral of pressure times distance minus friction.
The instantaneous recoil and instantaneous recoil are tightly related, but the felt recoil comes through the averaging filter of soft human flesh and gun mass.
The peak pressure's affect on the brass, primer, and gun are also time averaged, but with a faster time constant than than the bullet reaching the muzzle.
Generally things in the time domain are hard to get an intuitive feel for.
Re: Chamber pressure and recoil?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body"> JBM Recoil Calculator
Notice that chamber pressure is not one of the inputs.....</div></div>
That is a mighty slick calculator. I need to run home and weigh my boys gun now. Thanks for the link.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body"> JBM Recoil Calculator
Notice that chamber pressure is not one of the inputs.....</div></div>
That is a mighty slick calculator. I need to run home and weigh my boys gun now. Thanks for the link.
Re: Chamber pressure and recoil?
But JBM's recoil calculator does ask for charge weight, and charge weight <span style="text-decoration: underline">is</span> one of the variables that determines chamber pressure. Plus, muzzle blast definitely contributes to recoil, else muzzle brakes and suppressors wouldn't reduce felt recoil. And muzzle blast is a direct consequence of chamber pressure.
But JBM's recoil calculator does ask for charge weight, and charge weight <span style="text-decoration: underline">is</span> one of the variables that determines chamber pressure. Plus, muzzle blast definitely contributes to recoil, else muzzle brakes and suppressors wouldn't reduce felt recoil. And muzzle blast is a direct consequence of chamber pressure.
Re: Chamber pressure and recoil?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">But JBM's recoil calculator does ask for charge weight, and charge weight <span style="text-decoration: underline">is</span> one of the variables that determines chamber pressure. Plus, muzzle blast definitely contributes to recoil, else muzzle brakes and suppressors wouldn't reduce felt recoil. And muzzle blast is a direct consequence of chamber pressure. </div></div>
Hey Fred,
Take a 308 case and any old 155 grain bullet, and stuff it with "only" 35 grains of Bullseye and compare it to a load of 46.5 grains of Varget, and get back to me.
Note: You won't be able to measure recoil on the 30 gr of Bullseye load because your rifle will self-disassemble itself.
So charge weight (in the form of ejecta mass) is a variable in calculating recoil, as is velocity and weight of the projectile, but burn rate does have a affect on chamber pressure, that will not show up in the recoil column.
Bob
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">But JBM's recoil calculator does ask for charge weight, and charge weight <span style="text-decoration: underline">is</span> one of the variables that determines chamber pressure. Plus, muzzle blast definitely contributes to recoil, else muzzle brakes and suppressors wouldn't reduce felt recoil. And muzzle blast is a direct consequence of chamber pressure. </div></div>
Hey Fred,
Take a 308 case and any old 155 grain bullet, and stuff it with "only" 35 grains of Bullseye and compare it to a load of 46.5 grains of Varget, and get back to me.
Note: You won't be able to measure recoil on the 30 gr of Bullseye load because your rifle will self-disassemble itself.
So charge weight (in the form of ejecta mass) is a variable in calculating recoil, as is velocity and weight of the projectile, but burn rate does have a affect on chamber pressure, that will not show up in the recoil column.
Bob
Re: Chamber pressure and recoil?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">...So charge weight (in the form of ejecta mass) is a variable in calculating recoil, as is velocity and weight of the projectile, but burn rate does have a affect on chamber pressure, that will not show up in the recoil column.
Bob </div></div>
Sure it will. It's called "muzzle velocity."
If chamber pressure is zero, so is recoil. From that point on and until the moment of "self-disassembly," recoil increases directly with chamber pressure.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">...So charge weight (in the form of ejecta mass) is a variable in calculating recoil, as is velocity and weight of the projectile, but burn rate does have a affect on chamber pressure, that will not show up in the recoil column.
Bob </div></div>
Sure it will. It's called "muzzle velocity."
If chamber pressure is zero, so is recoil. From that point on and until the moment of "self-disassembly," recoil increases directly with chamber pressure.
Re: Chamber pressure and recoil?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">...So charge weight (in the form of ejecta mass) is a variable in calculating recoil, as is velocity and weight of the projectile, but burn rate does have a affect on chamber pressure, that will not show up in the recoil column.
Bob </div></div>
Sure it will. It's called "muzzle velocity."
If chamber pressure is zero, so is recoil. From that point on and until the moment of "self-disassembly," recoil increases directly with chamber pressure. </div></div>
Nope......
For example:
155 GR. SIE HPBT Hodgdon H322 .308" 2.775" 41.0 2710 49,400 CUP
155 GR. SIE HPBT Hodgdon Varget .308" 2.775" 47.0C 2909 49,400 CUP
The H322 load, has less recoil, and less velocity, but the pressure is identical to the Varget load. So you can get pressure without getting a corresponding velocity increase.
Recoil for the 47.0 grain Varget load in a 10 lb rifle is as follows:
Recoil Velocity:9.6 ft/s Recoil Energy: 14.3 ft•lbs
Recoil Impulse: 3.0 lb•s
For the 41.0 grain H335 Load:
Recoil Velocity:8.8 ft/s Recoil Energy: 11.9 ft•lbs
Recoil Impulse: 2.7 lb•s
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">...So charge weight (in the form of ejecta mass) is a variable in calculating recoil, as is velocity and weight of the projectile, but burn rate does have a affect on chamber pressure, that will not show up in the recoil column.
Bob </div></div>
Sure it will. It's called "muzzle velocity."
If chamber pressure is zero, so is recoil. From that point on and until the moment of "self-disassembly," recoil increases directly with chamber pressure. </div></div>
Nope......
For example:
155 GR. SIE HPBT Hodgdon H322 .308" 2.775" 41.0 2710 49,400 CUP
155 GR. SIE HPBT Hodgdon Varget .308" 2.775" 47.0C 2909 49,400 CUP
The H322 load, has less recoil, and less velocity, but the pressure is identical to the Varget load. So you can get pressure without getting a corresponding velocity increase.
Recoil for the 47.0 grain Varget load in a 10 lb rifle is as follows:
Recoil Velocity:9.6 ft/s Recoil Energy: 14.3 ft•lbs
Recoil Impulse: 3.0 lb•s
For the 41.0 grain H335 Load:
Recoil Velocity:8.8 ft/s Recoil Energy: 11.9 ft•lbs
Recoil Impulse: 2.7 lb•s
Re: Chamber pressure and recoil?
All I want to do is compare handloads and be able to tell approximately how much recoil the load will have in relation to what my son is shooting now. I appreciate the technical responses but to tell the truth, I was lost after the first one. I think I will go with the recoil calculator and save the headache for something else.
All I want to do is compare handloads and be able to tell approximately how much recoil the load will have in relation to what my son is shooting now. I appreciate the technical responses but to tell the truth, I was lost after the first one. I think I will go with the recoil calculator and save the headache for something else.
Re: Chamber pressure and recoil?
My father designed a lot of guns in the 50s through 80s, some fought in Nam. Israel still occasionally shoots up Lebanon with the M55.
He used "Hayes Elements of Ordinance", 1938
What does it all mean?
The momentum of the gun is the momentum of the projectile plus the momentum of the gas.
The momentum can result is a free recoil velocity of the gun or a max force of the gun against what constrains it, or a mixture.
If you calculate how far the gun moves back before it reaches max velocity, you can get some perspective on the difference between yourself and a rifle with a recoil pad, and a brass statue of a man and a rifle with a steel butt.
The first case takes it in velocity, the second case takes it in peak force.
I once put a hot load in a break action .410 and put the hard butt up against a concrete wall. The recoil broke the wrist of the stock.
What does THAT mean?
When it comes to calculating recoil, human bodies are like big pillows of softness.
My father designed a lot of guns in the 50s through 80s, some fought in Nam. Israel still occasionally shoots up Lebanon with the M55.
He used "Hayes Elements of Ordinance", 1938
What does it all mean?
The momentum of the gun is the momentum of the projectile plus the momentum of the gas.
The momentum can result is a free recoil velocity of the gun or a max force of the gun against what constrains it, or a mixture.
If you calculate how far the gun moves back before it reaches max velocity, you can get some perspective on the difference between yourself and a rifle with a recoil pad, and a brass statue of a man and a rifle with a steel butt.
The first case takes it in velocity, the second case takes it in peak force.
I once put a hot load in a break action .410 and put the hard butt up against a concrete wall. The recoil broke the wrist of the stock.
What does THAT mean?
When it comes to calculating recoil, human bodies are like big pillows of softness.
Re: Chamber pressure and recoil?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chuck1974</div><div class="ubbcode-body">Is there any correlation between chamber pressure and felt recoil? </div></div>
No. Chamber pressure is not one of the variables that determines recoil.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chuck1974</div><div class="ubbcode-body">Is there any correlation between chamber pressure and felt recoil? </div></div>
No. Chamber pressure is not one of the variables that determines recoil.
Re: Chamber pressure and recoil?
By the way, you asked about felt recoil. A recoil calculator will tell you absolute recoil but not felt recoil. Felt recoil is affected by many factors, such as stock design(drop and cast), buttplate material, buttplate surface area, your own stance and cheek weld, whether you hold the rifle tightly or not, your clothing, and psychological factors. There are skinny runts who can absorb huge recoil with no problem and there are bodybuilders who think a .270 kicks too much.
Recoil is also cumulative from a psychological standpoint. You may shoot 5 rounds of .338 Lapua well. It is unlikely you will shoot 100 rounds of .338 Lapua well in a day. But you could shoot 100 rounds of 5.56 well in a day.
By the way, you asked about felt recoil. A recoil calculator will tell you absolute recoil but not felt recoil. Felt recoil is affected by many factors, such as stock design(drop and cast), buttplate material, buttplate surface area, your own stance and cheek weld, whether you hold the rifle tightly or not, your clothing, and psychological factors. There are skinny runts who can absorb huge recoil with no problem and there are bodybuilders who think a .270 kicks too much.
Recoil is also cumulative from a psychological standpoint. You may shoot 5 rounds of .338 Lapua well. It is unlikely you will shoot 100 rounds of .338 Lapua well in a day. But you could shoot 100 rounds of 5.56 well in a day.
Re: Chamber pressure and recoil?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 500grains</div><div class="ubbcode-body">By the way, you asked about felt recoil. ... </div></div>
Search functioning some of your 505 Gibbs magazine articles, you mention the word "recoil" more often than the word "elephant".
What was bigger?
The elephant?
The recoil?
The bill?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 500grains</div><div class="ubbcode-body">By the way, you asked about felt recoil. ... </div></div>
Search functioning some of your 505 Gibbs magazine articles, you mention the word "recoil" more often than the word "elephant".
What was bigger?
The elephant?
The recoil?
The bill?
Re: Chamber pressure and recoil?
Ha!
I stepped on a black mamba, which struck but did not connect, and 2 minutes later I shot up a herd of elephants with that .505, the first one on a full charge at 6 yards. The mamba incident used up all my adrenaline so I was oddly nonplussed by the elephant shooting.
However, in general I think it is more likely that a person will be injured by a .505 Gibbs than by an elephant.
Ha!
I stepped on a black mamba, which struck but did not connect, and 2 minutes later I shot up a herd of elephants with that .505, the first one on a full charge at 6 yards. The mamba incident used up all my adrenaline so I was oddly nonplussed by the elephant shooting.
However, in general I think it is more likely that a person will be injured by a .505 Gibbs than by an elephant.
Re: Chamber pressure and recoil?
To take this to the extreme.
if you take any load mentioned and sealed the chamber and ignited that charge. Again no projectile movement. Chamber pressure would be the highest of any possible combinations. Yet recoil will be "0". Recoil is a product, kind of like horsepower. It is a result of torque and rpm. You must have both to come to a horsepower result. Now we can go with "Power" that is the calculation of horsepower over time. I look at recoil as "Power" minus effect of brake.
To take this to the extreme.
if you take any load mentioned and sealed the chamber and ignited that charge. Again no projectile movement. Chamber pressure would be the highest of any possible combinations. Yet recoil will be "0". Recoil is a product, kind of like horsepower. It is a result of torque and rpm. You must have both to come to a horsepower result. Now we can go with "Power" that is the calculation of horsepower over time. I look at recoil as "Power" minus effect of brake.
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