Explanation of Recoil Dwell Time Needed

[birch]

I recently had a member give me some advise on working up a good load for my Smith 29-2. I received alot of good useable information, but also got a response that got me a little puzzled.

A member suggested I use some Hs-6 in my .44 and said that the recoil dwell time was less than unique. I have heard members mention "dwell time" before, but had not really digested it, as I have never had a firearm that would benifit from an increased dwell time.

I am wanting to know a little bit about the theory and physics behind the trait. I assume it has everything to do with how fast or slow the powder is, but I can't help but think that projectile weight and shape might influence it as well.

Is there any way you might explain how a guy could experiment with a cartridge/firearm with some scientific certainty. For instance, a good friend had a beautiful Ruger Number 3 in 45/70. He ended up getting rid of it because it felt like someone kicked you square in the shoulder with factory ammo. I shot it twice and had broken blood vessels and deep tissue bruising. Is there any way my buddy could have kept velocity while decreasing felt recoil and if so, what is the logic to achieve it.

[Lloyd Smale]

never bought into it much. If im pushing a 300 grain bullet to 1100 fps i dont see a differnce in recoil between which powder im using to get it. If there is a difference its sure not enough to make one load comforable and one to much.

[RED333]

It has to do more with semis that use a gas tube, a timing thing between
when the bolt starts to move and the recoil you feel.
You change the position of the gas block on the barrel.

[308w]

Assuming you had to different loads with similar velocities but one was a "lighter load of fast powder" vs a "heavier charge of slower powder" the heavier charge load will have more recoil, since the weight of the powder is a factor of the recoil, but could you feel it on your shoulder,????

Ruger #3 in 45-70 is a fine piece of shooting equipment, but light guns in big calibers kick! There is no getting around that.

[rockrat]

Probably could have put a buttstock from a #1 on it and that would have helped. #3's are pretty light. Even the #1 in 45-70 can be a hanful with stout loads

[birch]

I can tell the difference in small handgun cartridges. Some powders seem to have a "slap" and others seem to have a "push" type of recoil in the same handgun and similar velocities.

[jmort]

Never heard that term. There is recoil "impulse." HS-6 is "slower" than Unique. It can be represented as a curve over time. Some of extreme slug loads in Hubel458's thread are using Steel or SR4759 and there is less felt recoil. That is also why there is less felt recoil with a .45 Colt shooting a 300 grain boolit and a .44 Mag shooting a 300 grain boolit at the same velocity, as the .45 Colt is operating at a lower pressure. For the loads Hubel458 is using, you will for sure fell the difference, especially north of 10,000 ft lbs, but even around 4 to 5 thousand foot pounds, there is a real difference.

[DougGuy]

It goes like this. When you fire any weapon, the laws of physics come into action full force. Ever heard the one that says "For every action, there is an equal but opposite reaction?"

Upon firing, the powder begins burning and builds pressure which forces the boolit out of the case and down the bore, eventually to leave the muzzle and fly toward it's target. At the same time, the pressure that forces the boolit forward, forces the receiver backwards. Here comes the equal but opposite part.

Since most firearms will move in the shooter's grip under this opposite reaction, the muzzle lifts, which affects point of impact. When you "sight in" a particular load, your sight adjustments will generally compensate for this movement. It's just a part of shooting. As you shoot heavier boolits, there is more movement produced since it takes more energy to force the heavier boolit down the bore, and therefore the resulting equal but opposite reaction causes more muzzle lift, and the sights must be re-adjusted to compensate for the additional movement in order to strike the target at the intended point of impact.

For a revolver, especially a single action revolver with fixed sights where there is no adjustment, choosing a powder/boolit combination that will "shoot to the sights" is critical. Too fast or too light a boolit will leave the muzzle before the recoil lifts it far enough to strike point of aim on the target because it has less dwell time (time in the barrel from the moment of ignition to exiting the muzzle) and will "shoot low." A heavier boolit takes longer to speed up because it requires more energy to break the force of intertia and start the boolit moving in the bore, so it has more dwell time, and the muzzle rise in the shooter's hands is greater, causing the heavier boolit to "shoot high."

Example #1: I have a 4 5/8" Vaquero in .45 Colt caliber. One certain 325gr boolit over 19.0gr of 2400 powder would strike the target 4" low in 25yds, 18.0gr resulted in the boolit striking 2" below point of aim, 17.0gr had it shooting to 1" below point of aim. The dwell time is shorter with 19.0gr of 2400 powder than it is with 17.0gr, so as the gun is fired, recoil causes the muzzle to rise, but since the boolit is traveling fast, it exits the bore before the muzzle rises far enough to shoot to point of aim. With the 17.0gr load, the boolit is traveling slower, and the muzzle has more time to rise, and it shoots to a higher point than the faster boolit. Developing loads for a single action which will allow it to strike point of aim is called "bringing the boolit to the sights." This is how you use dwell time to make your gun shoot to where the sights are pointed.

Example #2: I have a 7 1/2" SBH in .44 Magnum caliber. I wanted to develop a load with the very fine Lee C430-310-RF boolit. Knowing there is no way I will get 1250f/s velocity with a boolit this heavy, I anticipated the rear sight would not adjust low enough to sight the gun in with this load because the increased dwell time would have way more muzzle rise than the sights were able to compensate for. Upon shooting this boolit over 16.0gr of 2400, I discovered that I was right, and it was hitting the target a full 5" above point of aim at 25yds. Not being faint of heart, I took the gun to a vise and very carefully filed down the rear sight blade until it was even with the body of the sight, then refiled the notch in the center of the blade. Now the gun shoots beautiful groups, directly on top of the front sight blade, with these heavy boolits.

So to explain recoil dwell time, it is not describing how hard or how sharp the felt recoil is, it is describing the amount of time the boolit is in the bore, which affects the point of impact due to the movement of the firearm in the shooter's hands during firing.

In general, lighter boolits have less dwell time than heavy boolits. A higher velocity load will have less dwell time than a standard velocity load. How fast or how slow the powder burns isn't the determining factor, it's how fast the boolit is driven out the muzzle which determines the amount of dwell time.

[oneokie]

It goes like this. When you fire any weapon, the laws of physics come into action full force. Ever heard the one that says "For every action, there is an equal but opposite reaction?"

Upon firing, the powder begins burning and builds pressure which forces the boolit out of the case and down the bore, eventually to leave the muzzle and fly toward it's target. At the same time, the pressure that forces the boolit forward, forces the receiver backwards. Here comes the equal but opposite part.

Since most firearms will move in the shooter's grip under this opposite reaction, the muzzle lifts, which affects point of impact. When you "sight in" a particular load, your sight adjustments will generally compensate for this movement. It's just a part of shooting. As you shoot heavier boolits, there is more movement produced since it takes more energy to force the heavier boolit down the bore, and therefore the resulting equal but opposite reaction causes more muzzle lift, and the sights must be re-adjusted to compensate for the additional movement in order to strike the target at the intended point of impact.

For a revolver, especially a single action revolver with fixed sights where there is no adjustment, choosing a powder/boolit combination that will "shoot to the sights" is critical. Too fast or too light a boolit will leave the muzzle before the recoil lifts it far enough to strike point of aim on the target because it has less dwell time (time in the barrel from the moment of ignition to exiting the muzzle) and will "shoot low." A heavier boolit takes longer to speed up because it requires more energy to break the force of intertia and start the boolit moving in the bore, so it has more dwell time, and the muzzle rise in the shooter's hands is greater, causing the heavier boolit to "shoot high."

Example #1: I have a 4 5/8" Vaquero in .45 Colt caliber. One certain 325gr boolit over 19.0gr of 2400 powder would strike the target 4" low in 25yds, 18.0gr resulted in the boolit striking 2" below point of aim, 17.0gr had it shooting to 1" below point of aim. The dwell time is shorter with 19.0gr of 2400 powder than it is with 17.0gr, so as the gun is fired, recoil causes the muzzle to rise, but since the boolit is traveling fast, it exits the bore before the muzzle rises far enough to shoot to point of aim. With the 17.0gr load, the boolit is traveling slower, and the muzzle has more time to rise, and it shoots to a higher point than the faster boolit. Developing loads for a single action which will allow it to strike point of aim is called "bringing the boolit to the sights." This is how you use dwell time to make your gun shoot to where the sights are pointed.

Example #2: I have a 7 1/2" SBH in .44 Magnum caliber. I wanted to develop a load with the very fine Lee C430-310-RF boolit. Knowing there is no way I will get 1250f/s velocity with a boolit this heavy, I anticipated the rear sight would not adjust low enough to sight the gun in with this load because the increased dwell time would have way more muzzle rise than the sights were able to compensate for. Upon shooting this boolit over 16.0gr of 2400, I discovered that I was right, and it was hitting the target a full 5" above point of aim at 25yds. Not being faint of heart, I took the gun to a vise and very carefully filed down the rear sight blade until it was even with the body of the sight, then refiled the notch in the center of the blade. Now the gun shoots beautiful groups, directly on top of the front sight blade, with these heavy boolits.

So to explain recoil dwell time, it is not describing how hard or how sharp the felt recoil is, it is describing the amount of time the boolit is in the bore, which affects the point of impact due to the movement of the firearm in the shooter's hands during firing.

In general, lighter boolits have less dwell time than heavy boolits. A higher velocity load will have less dwell time than a standard velocity load. How fast or how slow the powder burns isn't the determining factor, it's how fast the boolit is driven out the muzzle which determines the amount of dwell time.

Correct answer.

[felix]

That's an extremely good description of what happens. In addition: Having the very same acceleration PATTERN for each of the projectiles determines the group size printed by all of the projectiles, where as the amount of dwell time per each projectile determines the point of impact of each. From an old time cigarette ad on TV: "It's not how long it is, it is how it is made long." ... felix

[birch]

Thanks a bunch everyone--makes sense.

[cbrick]

DougGuy is correct in his description but left out one very important aspect regarding point of impact and that is grip. Change your grip even slightly from shot to shot and you change the amount of muzzle rise thus changing the point of impact, the longer the range the more critical grip becomes and the more change in point of impact.

Another common term for dwell time is barrel time which usually means lock time, ignition time and barrel time. In other words from the time you have a sight picture and the sear breaks until the bullet clears the muzzle. In a revolver that is more time than many realize giving you plenty of opportunity to move the gun from your sight picture & sear break to bullet exit thus point of impact not where you thought.

Getting a bit off topic except dwell time and grip go hand in hand.

Rick

Rick

[Hickory]

Explanation of recoil.
For every action, there is an equally and opposite reaction.

[RED333]

Doug, I have learned something today, Thanks Man.

[DougGuy]

That's an extremely good description of what happens. In addition: Having the very same acceleration PATTERN for each of the projectiles determines the group size printed by all of the projectiles, where as the amount of dwell time per each projectile determines the point of impact of each. ... felix

Very well stated felix. This is why it is important to address cylinder throat diameters, because if you have a tight one or two out of six, those chambers will shoot to a different point of impact than the loose chambers. However the BIGGEST cause of standard deviation (changing velocity which also changes dwell time from shot to shot) would be the powder measure. I always weigh each and every charge when I am developing a load, because I want to minimize all the variables so they don't skew my findings and open up group sizes. I also weigh each charge for my hunting ammo. Also, the neck tension and how much of what style of crimp, and how consistent the crimp is plays a big part in dwell time because that little bit of resistance is necessary to allow the powder to start burning properly before boolit movement multiplies the case volume as it lights off. Loose or inconsistent crimp = premature boolit movement = different pressure curve = different dwell time = different point of impact.


DougGuy is correct in his description but left out one very important aspect regarding point of impact and that is grip. Change your grip even slightly from shot to shot and you change the amount of muzzle rise thus changing the point of impact, the longer the range the more critical grip becomes and the more change in point of impact.

Another common term for dwell time is barrel time which usually means lock time, ignition time and barrel time. In other words from the time you have a sight picture and the sear breaks until the bullet clears the muzzle. In a revolver that is more time than many realize giving you plenty of opportunity to move the gun from your sight picture & sear break to bullet exit thus point of impact not where you thought.

Getting a bit off topic except dwell time and grip go hand in hand.

Rick

They do, and I didn't leave that part out, I consider grip and lock time a separate part of firing than dwell time so I did not address that as the OP was only asking how to best understand dwell time. But you are correct. Anything that affects the upward arc of the muzzle as the gun fires will affect point of impact, but it does not affect dwell time or barrel time as you call it.

This is (to me) one of the most fascinating areas of study when it comes to firearms, the physics and ballistics involved in shooting the single action revolver. There is no other firearm that incorporates so much of the shooter's movements into such a simple event.

[cbrick]

I didn't say or imply that grip changes dwell time (barrel time) just that while the bullet is still in the barrel changing the grip does change the amount of muzzle rise. If the bullet hasn't left yet changing the position of the muzzle (via grip) changes point of impact. Because of that the two go hand in hand, what makes the grip so critical on a revolver is the dwell time. Many people use the term barrel time when it is dwell time they are referring to, just something I'm accustomed to I guess.

Like you I am a lover of long range revolver and spent 30 years competing and revolver is the vast majority of my shooting, casting & loading.

I wasn't trying to say you were wrong, in fact I said that you were right, just that I feel the two go together.

Rick

[DougGuy]

It's all good Rick, and you are correct about both going together. One of the things I do and also teach/preach to others is to dry fire. I find that most factory single actions need less trigger pull to be fired accurately because once the sear breaks, you have considerable overtravel and with the added effort of a stiff trigger, there's no way you will have good groups. To that end I usually swap the trigger spring for a lighter one and sometimes the hammer spring as well, until I can dry fire and the sights stay motionless. Many shooters can't figure out why their gun doesn't shoot very well, and there is a definite need for them to find out is it the gun or is it me. Dry firing, practicing the right grip, lightening the trigger, all that smoothes out any errors or variables you introduce during lock time.

So yeah it's not only dwell time, but lock time/hammer fall, overtravel control (or put a screw behind the trigger like I did with my Vaquero), grip, sight picture, and so on but we are on the same page..

[Maven]

Excellent, well presented post (#8), DG!

[felix]

Another common term for dwell time is barrel time which usually means lock time, ignition time and barrel time.

Actually, Rick, that is the true definition. You might also include the time between "pull" and "trigger trip" to the definition. That is paramount in BR shooting which the brain sees an atmospheric condition exactly the same as the last shot. ... felix

[birch]

"That is paramount in BR shooting which the brain sees an atmospheric....."

Felix, I always enjoy your explanations on shooting technique and theory. Could you explain what you meant by the above statement.

Also, I still have a tub and a half of your original batch "Felix Lube". It is perfect and as close as I have ever came to a universal lube. My hat is off to you.

[smoked turkey]

Most interesting. Thanks to all for this topic and its suburb explanations.

[felix]

Birch, in BR competition the gun, ammo, and style of shooting are the least of problems to win a day's worth of match shooting. It's being able to read the wind currents (direction and speed) and lighting changes (cloud cover), called together as the conditions, during a 5 or 10 shot group event. When the conditions are to the liking of the shooter's style, the shooter shoots one shot, then waits for the same condition to reappear before shooting another. The winner of the day's shoot is invariably the best weather person for THOSE set of conditions presented that day. All BR guns entered for the individual relays are essentially the same in terms of winning the whole match. ... felix

[Win94ae]

Not this again.


From an Engineer working on the m198 Howitzer and the new 105mm Hawkeye at Rock Island Arsenal.

At initial ignition of the charge, there is a small and barely perceptible motion of the barrel/breach. (only detectable by sensitive instrumentation) However, this motion is of so little significance that it has no practical effect on POI.

However, the motion widely accepted as recoil, were it to take place while the projectile were still in the barrel, would make POI so unpredictable as to make any sighting system useless; nothing more than decoration on the weapon.


From an actual physicist;
88640

I have done extensive testing, and only found a POI shift due to recoil under extreme circumstances.

http://www.youtube.com/watch?v=JcR1meidxaI
Recoil Testing (http://www.youtube.com/playlist?list=PLC9D5E0275FB0D6B3&feature=mh_lolz)

Where it has been discussed thoroughly.
Gun Recoil vs POI (http://www.thefirearmsforum.com/showthread.php?t=100867&page=2) It gets interesting at comment #37.

[Win94ae]

Example #1: I have a 4 5/8" Vaquero in .45 Colt caliber. One certain 325gr boolit over 19.0gr of 2400 powder would strike the target 4" low in 25yds, 18.0gr resulted in the boolit striking 2" below point of aim, 17.0gr had it shooting to 1" below point of aim.

Then why did my POI rise as my charge weight increased during my ladder test today?

https://www.youtube.com/watch?v=Qb2UEszMaoI

From 50gr to 52.8gr, the POI climbed 2 feet.

[jmort]

"Not this again."

Makes sense that the boolit wold be long gone before someone could sense it or have an affect on the point of impact. The link to the thread you provided is most interesting. Also makes sense that most of this is folderol. Thanks

[Win94ae]

Example #2: I have a 7 1/2" SBH in .44 Magnum caliber. I wanted to develop a load with the very fine Lee C430-310-RF boolit. Knowing there is no way I will get 1250f/s velocity with a boolit this heavy, I anticipated the rear sight would not adjust low enough to sight the gun in with this load because the increased dwell time would have way more muzzle rise than the sights were able to compensate for. Upon shooting this boolit over 16.0gr of 2400, I discovered that I was right, and it was hitting the target a full 5" above point of aim at 25yds. Not being faint of heart, I took the gun to a vise and very carefully filed down the rear sight blade until it was even with the body of the sight, then refiled the notch in the center of the blade. Now the gun shoots beautiful groups, directly on top of the front sight blade, with these heavy boolits.

Are you sure the POI irregularity is due to recoil and not other issues, one being aerodynamic properties?
http://img.photobucket.com/albums/v39/justgoto/gun/357POIs.jpg

I have found this issue many times. A bullet of a precise load, traveling 200fps above the speed of sound, will hit lower than a accurate load traveling almost subsonic. When you the velocity climbs to 400fps higher than the speed of sound, you'll see an increase in POI height.

Confusing Cause and Effect (http://www.nizkor.org/features/fallacies/confusing-cause-and-effect.html)

[birch]

I read through the first 4 pages of that thread and I have to say that I gained absolutly nothing from it! It seemed that just as someone reached a finality, another person woud chime in with a different viewpoint of how they approached the problem and change the variables, which invariably started another explanation that was correct and also wrong at the same time.

For those of you much smarter than I: What was the conclusion?

Let me ask this another way and please answer this one question: At some point, I feel a recoil impulse of which my bodily force needs to exert a pressure to stop the rearward momentum of the gun. At what point does the recoil impulse actually come into existance..I.E> the point in which my hand actually feels the rearward momentum of the firearm--the initial ignition, the bullet moving through the barrel, or the instant the bullet leaves the barrel?

[jmort]

"I read through the first 4 pages of that thread and I have to say that I gained absolutly (sic) nothing from it!"

Win94ae said it got interesting at post #37 and he was right. This thread "concluded" that the POI was impacted while the bullet was in the bore. Apparently wrong, way wrong. I agree with the proposition that the bullet is long gone and cannot, by definition effect the POI. Then most every other post was a huzza and group think.

[Win94ae]

"Not this again."

Makes sense that the boolit wold be long gone before someone could sense it or have an effect on the point of impact. The link to the thread you provided is most interesting. Also makes sense that most of this is folderol. Thanks

First, thank you for bring that word, "folderol" to my attention! :)

I sometimes bite my tongue when this issue comes along; but if some site members are interested in a better understanding of internal and external ballistics, I feel an obligation.

[jmort]

I got a lot to learn, but I am still interested in the issue of "impulse." As noted, it comes up a lot in discussion of shotgun powders, and when you get crazy insane loads 5k ft lbs or 10k ft lbs or 15k ft lbs of energy, those most experienced claim the slower burning powders are much easier on the shoulder. Like Hubel458 shooting a 9,000 ft lb load out of a 9 pound pistol grip shotgun. My hat's off to that man.

[Win94ae]

I read through the first 4 pages of that thread and I have to say that I gained absolutly nothing from it!
You got nothing from the experiments?
Nothing from the expert testimony?
Nothing from the physics calculations?


For those of you much smarter than I: What was the conclusion?
Now the thinly veiled insults, isn't that wonderful!


Let me ask this another way and please answer this one question: At some point, I feel a recoil impulse of which my bodily force needs to exert a pressure to stop the rearward momentum of the gun. At what point does the recoil impulse actually come into existance..I.E> the point in which my hand actually feels the rearward momentum of the firearm--the initial ignition, the bullet moving through the barrel, or the instant the bullet leaves the barrel?

This answers/answered both questions.

"However, the motion widely accepted as recoil, were it to take place while the projectile were still in the barrel, would make POI so unpredictable as to make any sighting system useless; nothing more than decoration on the weapon."
That paragraph is found in my initial post.... which speaks to your "I read through the first 4 pages" comment too.

[birch]

I must be the elephant in the room, but right now, I feel more like the ***. I studied that baby, and it seems to me that the concensus is that gravity and atmosphere are the true culprits of POI. The firearm has nothing to do with it. Is this correct? If it truly is correct, I can do my own headwork to understand the physics.

[Win94ae]

I must be the elephant in the room, but right now, I feel more like the ***. I studied that baby, and it seems to me that the concensus is that gravity and atmosphere are the true culprits of POI. The firearm has nothing to do with it. Is this correct? If it truly is correct, I can do my own headwork to understand the physics.

Fallacy: Straw Man (http://www.nizkor.org/features/fallacies/straw-man.html)


The Straw Man fallacy is committed when a person simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position. This sort of "reasoning" has the following pattern:


Person A has position X.
Person B presents position Y (which is a distorted version of X).
Person B attacks position Y.
Therefore X is false/incorrect/flawed.

[birch]

I guess all I can say is Wow!!! I know you are an expert at reading between the lines and all that. Hopefully you can extrapolate the word "Wow" in the context in which it is written. If you can't, hopefully others who read my questions and then your answers to my questions can.

[Win94ae]

I'll ignore the thread now.

[birch]

Never mind my previous post--I have a little more to say.

You post the findings of a Howitzer engineer and a website full of seven pages of BS and assume that everyone will understand the entire scope of the concept? Excuse me, but I guess I forgot where I put my degree in calculus based physics. Then you bring out yet another algebraic expression and substitute man as a "variable" and ultimatly place me as the product of your cute and unbrilliant little insult. Like most people on this website, I am man who likes to have a better understanding on how things work and once the understanding comes to light, find ways to make life easier as a result. At first, you seemed like a mentor. Now, I know that my 3 year old son has a better understanding of the ways of life than you do. You may be a smart man, but I can do without smart men like you. I will say farewell, and hope you never attempt to answer a question on any of the posts that I am a part of. My suggestion--go dig through some old calculus textbooks and figure out how to make an efficient and practical cold fusion method. At least then, I can think of how much money you saved me every time I flush the toilet.

[birch]

Since I am a fair man, and believe in the whole eye for an eye viewpoint of life, I must add one more piece of insight. You insulted me three times. Its only fair that I make it right.
Win94,

There is a reason why guys like me think that it should not take 3 or 4 hours to change a thermostat in a vehicle. Often, when we don't understand why an engineer would place a thermostat under a mountain of ****, we might say "Damn Engineers".

While at the same time, you engineers just can't quite figure out what the big deal is.

Guys like me like to eliminate variables, while you and your cohorts cant help but to create more of them. 2+2=4

[DougGuy]

Are you sure the POI irregularity is due to recoil and not other issues, one being aerodynamic properties?


If I fire that SBH from a solid pistol rest, then fire it offhand by resting my forearms on an ammo can, the POI rises 2" @25yds. Why? Because the forces of recoil lift the muzzle more and rotate the butt downward more when there is not a solid rest under the butt of the gun. Doesn't take an engineering degree to figure that one out.

Your recoil testing video does not begin to compare to the energy produced by lighting off a healthy charge of 2400 under a 310gr boolit. You have maybe 1 1/2" of muzzle rise, where I have several inches. Try that test with a real handcannon and see how different your results are.


Then why did my POI rise as my charge weight increased during my ladder test today?

From 50gr to 52.8gr, the POI climbed 2 feet.

You are firing a rifle, totally different set of variables, again cannot even compare to a short barreled Vaquero. My example is given for that specific gun, and not a statement that all guns when fired, follow the same rules. A single action revolver has a rotational axis somewhere near the shooter's middle finger on the grip frame, the rifle has no measurable rotational axis. The forces that affect POI on a revolver are only slightly similar to those that affect POI on a rifle. Offhand I would say that your POI rose because the recoil increased enough to add to the muzzle rise with the heavier charge.

Were you to shorten the barrel and fit the levergun with a pistol grip, you would likely see a totally different set of noticeable reactions when firing than with the long barrel and long buttstock.

[cbrick]

I read over all of the above and in reality saw nothing to comment on. Written by someone with a slide rule and text book that has never tried hitting a 200 meter target with a big bore revolver.

Rick

[fecmech]

This thread "concluded" that the POI was impacted while the bullet was in the bore. Apparently wrong, way wrong. I agree with the proposition that the bullet is long gone and cannot, by definition effect the POI.
The video was a bit bogus, if you notice the target was only 10 yds but even then there were two groups with a vertical difference showing the effect of muzzle rise. Move the target to 25 or 50 yds and you will see quite a bit of difference
If one looks closely at revolvers you will notice that the front sight is always higher than the rear which places the line of the bore below the target prior to ignition. The reason for that is to compensate for muzzle rise and the barrel time till bullet exit.

[felix]

As long as sighting is done via the gun's attached apparatus, the gun is fired according to the gun's sights and resulting POI is based upon that sighting. Not so with guided missles where sighting is done in projectile real-time. There is an in-between situation, like when sighting was done on the battleship used during the VietNam conflict. The sighting was completely computerized taking the position of the gun and atmospheric conditions into consideration before firing by the COMPUTER. That battleship never fired for a pre-effect because there was no need. It could hit a target, guaranteed, within a minute and a half from one mile through more than 20 miles. Can you "see" a target the size of a square football field at 20-26 miles, which would be over the horizon anyway? ... felix

[DougGuy]

The video was a bit bogus, if you notice the target was only 10 yds but even then there were two groups with a vertical difference showing the effect of muzzle rise. Move the target to 25 or 50 yds and you will see quite a bit of difference
If one looks closely at revolvers you will notice that the front sight is always higher than the rear which places the line of the bore below the target prior to ignition. The reason for that is to compensate for muzzle rise and the barrel time till bullet exit.

Exactly.

[Airman Basic]

:confused:Now, could you geniuses, genii?, help me understand the concept of dwell time of a boolit on a steel target?

[cbrick]

Think high speed photography. Now think freeze frame, looking at one frame at a time. You have a fairly low Sb alloy bullet and in this frame the nose just makes contact with the steel target, next frame the bullet is still pushing onto the target and deforming. The bullet continues onto the target in each frame deforming until the base reaches the target. The time it takes for the bullet to expend ALL of it's momentum onto the target is the dwell time on target.

Now consider the same high speed photography only substitute a high Sb alloy bullet. The nose hits the target only instead of expending all of it's momentum pushing onto the target momentum is lost via the bullet cracking and coming apart. Shattering. Considerably less dwell time on target because much of the bullet momentum is gone before the rear of the bullet gets to the target.

This is the reason that 25 years ago I stopped using lino on steel targets, dwell time on target (momentum on target). Tough enough to hit all of the 200 meter rams without getting good hits and having them standing there laughing at you.

Rick

[beezapilot]

Well I, for one, learned a great deal. I'm an avid trap shooter and with the un-availability of my favorite powder have used whatever is on the shelf. Using the loading manual, I've tried to match the shot velocity of my standard trap load... but thought my calculations were off due to the amount of adjustment that was sometimes required. BURN RATE - the "slap" vice the "push" impacting my shot string.

[blackthorn]

Quote "Now, could you geniuses, genii?, help me understand the concept of dwell time of a boolit on a steel target?"

This question was followed by an explanation and now I am confused.
Am I missing something here? I understood (at least in relation to this thread) that we were disscussing "dwell" time with respect to the time a bullet spends in the barrell before it exits and the combination of that time along with differing bullet weights (lighter vs. heavier) on POI. I am not being critical here, it is just that I had never considered "dwell" time in any context other than what I understood the OP to adress.

[cbrick]

blackthorn, your correct, just a different question was asked regarding dwell time. Most commonly it refers to barrel time but it's also used in regards to time on target when shooting steel.

Rick

[felix]

I have used the term "stick time" in lieu of dwell time on a target. You might include the same meaning as the projectile to be "within" an animal. ... felix

[Sensai]

[QUOTE=Win94ae;2494023]
However, the motion widely accepted as recoil, were it to take place while the projectile were still in the barrel, would make POI so unpredictable as to make any sighting system useless; nothing more than decoration on the weapon.

So you're saying that Newton's third law of motion is temporarily suspended from the time force is applied to the projectile until it actually leaves the barrel? You may want to rethink that one. A howitzer and a handgun are two different animals, but physics is physics. The barrel/chamber and everything attached to it WILL start moving at the same time as the projectile starts moving.

[cbrick]

Precisely Sensai,

As I posted earlier, written by someone with a slide rule and a book but zero logic or experience and not worthy of further consideration.

Just as with Hollywood firearms where they have zero recoil (that would make this discussion mute huh?) and they never run out of ammo, just keep on a shootin. But reality doesn't live in fantasy town or in that point of view.

Rick

[popper]

written by someone with a slide rule
Neither Newton nor Pythagoras had one, but without persons with that mentality, we would still be throwing rocks. And trying to catch horses?

[cbrick]

Fine, buy into that nonsense, no skin off my hieny.

Next time you quote someone quote the entire sentence not just the few words that you think will make your point.


As I posted earlier, written by someone with a slide rule and a book but zero logic or experience and not worthy of further consideration. Rick

Rick

[felix]

Rick, it's all in the wording of what is meant. The English language sucks because it is so variable/expansive as opposed to something like Latin which has been scholarly fixed in time. Dwell time to gun folks can be thought of as the mean time between the THOUGHT of the shot and the deer on the TABLE. Dwell time had been defined much earlier by almost everyone as the time to sequentially fire spark plugs by using a mechanical or electronic timing device (a distributor, or a computer nowadays). ... felix