Pistol Firing Slow Motion

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Pistol Firing Slow Motion

Post by beeser on Mon Nov 30, 2015 10:25 pm


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Re: Pistol Firing Slow Motion

Post by 1joel1 on Tue Dec 01, 2015 11:06 am

That's really cool. You can even see the bullet spinning.

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Re: Pistol Firing Slow Motion

Post by Jerry Keefer on Tue Dec 01, 2015 11:24 am

Yes, that flick, and at least one other shown recently,  shows that the belief of  the muzzle/slide  moving rearward before the bullet exits is false..

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Re: Pistol Firing Slow Motion

Post by Jon Eulette on Tue Dec 01, 2015 12:02 pm

Would be cool to see a close up difference between match pistol and stock pistol of the barrel to see if it twist/rotates from torque as cartridge is fired. I know it's minute, but nevertheless would be cool to see. Or movement of loose bushing, or ejection port view on stock barrel; hood play (side to side & for and aft), and barrel dropping or raising vertically from loose slidestop fit.
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Re: Pistol Firing Slow Motion

Post by beeser on Tue Dec 01, 2015 4:47 pm

If you pause the video just as the bullet exits the muzzle you can see a fair amount of smoke in advance of the bullet and at the breach.  I don't know what that means other than the chamber is not fully sealed allowing products of combustion to exit ahead of the bullet and back around the case.

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Re: Pistol Firing Slow Motion

Post by BE Mike on Tue Dec 01, 2015 5:12 pm

beeser wrote:If you pause the video just as the bullet exits the muzzle you can see a fair amount of smoke in advance of the bullet and at the breach.  I don't know what that means other than the chamber is not fully sealed allowing products of combustion to exit ahead of the bullet and back around the case.
That could be the result of heat from friction of the bullet traveling in the barrel and not propellant gases.

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Re: Pistol Firing Slow Motion

Post by Jerry Keefer on Tue Dec 01, 2015 6:57 pm

The bullet does not begin to accelerate any where near the speed of the expanding gases.. Therefore a fair amount of the gas gets past and ahead of the bullet before it enters and seals the bore.

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Re: Pistol Firing Slow Motion

Post by Wobbley on Tue Dec 01, 2015 8:44 pm

Jerry Keefer wrote:Yes, that flick, and at least one other shown recently,  shows that the belief of  the muzzle/slide  moving rearward before the bullet exits is false..
Then why do revolvers actually point the bores below the line of sight?  The recoiling parts begin to move as soon as the bullet does, but hey don't move as far or as quickly.

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Re: Pistol Firing Slow Motion

Post by SMBeyer on Tue Dec 01, 2015 8:56 pm

I don't mean to be argumentative but I thought the video clearly showed the slide moving before the bullet left the barrel.

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Re: Pistol Firing Slow Motion

Post by beeser on Tue Dec 01, 2015 9:00 pm

Another slomo video but with a revolver ...


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Re: Pistol Firing Slow Motion

Post by james r chapman on Tue Dec 01, 2015 10:47 pm

interesting, a careful review of the video does show the slide in recoil before the bullet leaves the barrel, but, the barrel remains in lockup until the bullet has left the barrel.

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Re: Pistol Firing Slow Motion

Post by Jon Eulette on Tue Dec 01, 2015 11:04 pm

Lockup is relative ;p)
That's why we have BE smiths.
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Re: Pistol Firing Slow Motion

Post by ak41 on Tue Dec 01, 2015 11:21 pm

If the slide is in recoil even slightly doesn't the link begin to pull the barrel down out of lock slightly also?  Wouldn't it follow then that grip consistency (hold strength, etc.) would effect bullet impact point versus initial aiming point?
Al

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Re: Pistol Firing Slow Motion

Post by Wobbley on Tue Dec 01, 2015 11:27 pm

The link can only pull the barrel down if the bottom of the barrel lugs are off the slide stop pin.  That's why the smiths fit the pin and allow for an overlap of a few thousandths.

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Re: Pistol Firing Slow Motion

Post by james r chapman on Tue Dec 01, 2015 11:28 pm

If you look carefully at your 1911 you'll see the slide and barrel stay in lockup for a reasonable distance before the link pulls the barrel down.

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Re: Pistol Firing Slow Motion

Post by ak41 on Tue Dec 01, 2015 11:35 pm

Thanks for the reply, I guess I was thinking that the previous comment about "slightly" was more than the overlap..

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Re: Pistol Firing Slow Motion

Post by Jerry Keefer on Wed Dec 02, 2015 8:55 am

Wobbley wrote:
Jerry Keefer wrote:Yes, that flick, and at least one other shown recently,  shows that the belief of  the muzzle/slide  moving rearward before the bullet exits is false..
Then why do revolvers actually point the bores below the line of sight?  The recoiling parts begin to move as soon as the bullet does, but hey don't move as far or as quickly.

Sights, ribs, optics are installed,  parallel to the C/L of the bore..  1911 ribs, slide mounts and frame mounts, both open, and optic have an approx.  1 degree forward taper.. Same approx angle as the barrel fit.. Revolvers, rifles, shotguns are no different. The debate on how much the slide moves or doesn't move during the ignition event has raged for years in every forum on the net.. Every video shows a 1911 with varying degrees of movement. Some have a great deal, others such as the one shown have very little to none..About 20 years ago, the 1911 . org forum debate wore on for months..  I solicited input from one of the worlds leading  firearms manufacturer head engineer. One of their duties when developing a firearm is to high speed video the ignition event.. This allows accurate evaluation of slide speed and frame flex. My answer mirrors his.. Think about a minimum of 8000 psi chamber pressure lead semi wadcutter for bullseye.. as far as the unlocking issue. It's not unlocking until that pressure drops..The two cannot separate at that pressure.. If the slide attempted to unlock under pressure, something is going to break.. I am talking unlock...     It's a tiring, meaningless debate that I am not going to pursue..


Last edited by Jerry Keefer on Wed Dec 02, 2015 3:23 pm; edited 1 time in total

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Re: Pistol Firing Slow Motion

Post by ak41 on Wed Dec 02, 2015 12:18 pm

Thanks for the added perspective Jerry.
Al

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Re: Pistol Firing Slow Motion

Post by C.Perkins on Sun Dec 06, 2015 9:33 am

A video from another site I frequent, a cut away .45 in slow motion.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwihq5LqqsfJAhWJo4MKHXdeAbAQtwIIHjAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Djig-RvZr1OM&usg=AFQjCNFCDm-3ERdbT78IlKjBSx0oAx7RYw

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Re: Pistol Firing Slow Motion

Post by inthebeech on Sun Dec 06, 2015 1:23 pm

What is happening that "The two cannot separate at that pressure?" What mechanical /kinematic relief develops when the pressure drops to the value that permits the unlocking?
This isn't taught in engineering school (or I blew it off which would be the case if it were a Friday morning class) Smile

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Re: Pistol Firing Slow Motion

Post by Jon Eulette on Sun Dec 06, 2015 2:27 pm

I wonder if its the bolt thrust? Not sure what it is for .45acp, but it's enough to put markings from bolt face on bottom of the case.
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Re: Pistol Firing Slow Motion

Post by r_zerr on Sun Dec 06, 2015 11:39 pm

inthebeech wrote:What is happening that "The two cannot separate at that pressure?" What mechanical /kinematic relief develops when the pressure drops to the value that permits the unlocking?
This isn't taught in engineering school (or I blew it off which would be the case if it were a Friday morning class) Smile

Pressure goes up to whatever your loads are.
For arguments sake, lets say a 45 acp, at 10,000 psi.  If only .5 inch case length is involved, and .46" diameter, and coefficient of friction between brass and steel (quick recollection, good only for demonstration here),  the forces to extract the case from the barrel are:
 
   pressure x diameter x pi x length x coefficient of friction =  10,000 * .46 * 3.14 * .5 * .1 = 722 lbs force.

The slide and barrel stay locked up, otherwise, you would have a broken gun.  Take care of your brass so it can do its job when the big fire comes.

The movement of the slide and barrel is purely from the energy of the acceleration of the bullet, and separation of the two along with the extraction of the brass cannot occur until the pressure drops to release the grip between the brass and the barrel.

-ron

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Re: Pistol Firing Slow Motion

Post by Wobbley on Mon Dec 07, 2015 12:40 am

The velocity of the slide and barrel is a fundamental of the momentum in the bullet.  M1V1=M2V2.  Elementary kinematics.  Since the slide weighs about 35 times the bullet, the velocity is 1/35th that of the bullet

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Re: Pistol Firing Slow Motion

Post by inthebeech on Fri Dec 11, 2015 7:04 am

cheers Friction between the case and barrel?  Ok, but there is still movement that may take place instantaneously it seems; this would be the entire assembly of barrel, case, and slide, but only as far as they can before the friction that you described keeps further movement from happening? So are you saying that barrel (with case still in place) and slide are pushed back but only until the barrel's lower lugs smack the frame's vertical surface and then wait there until pressure drops, permitting the remainder of the movement now to take place (which now is only the slide which has a hold of the case rim)?   I suspect that mass plays a role here as well as an "average" pressure curve and the length of the link (and slide mass) permit the actual motion to be continuous; i.e. the rearward travel is a very carefully designed value (by setting link length appropriately) to permit the pressure to drop enough to release the grip between case and chamber just about the time that the barrel smacks the frame.
Or it could be completely different. jocolor

Wobbley has an interesting factoid about relative velocities.  Pretty cool friend.  It is probably a bit more complicated because I think we are dealing with accelerations not velocities and the barrel assembly has angular movement, not linear; so probably not 'elementary' and conservation of momentum between angular and linear components of one system involving accelerations - well that just makes my head hurt.

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Re: Pistol Firing Slow Motion

Post by RustyJoints on Fri Dec 11, 2015 10:16 pm

All proving Mr. Browning was a genius.

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Re: Pistol Firing Slow Motion

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