Bolt slide back length

[jeff-portnoy]

Hi.
Please tell me guys,
What is slide back length must-have a bolt, before tripping with barrel for safety after shot!?!
(Browning system handguns 9x19 of course)

 

[Jim K]

I really don't understand the question. If you mean how far back does the slide on a auto pistol have to come, the answer is that it must come back far enough to make sure the fired case ejects and the slide picks up the next cartridge when it moves forward.

If you mean how far must the slide and barrel of a locked breech pistol travel back together before unlocking, that is an issue involving both the gun design and the cartridge. There really is no fixed distance but, as a general answer, about 1/4-3/8 inch.

Jim

 

[1911Tuner]

This old fluroscope photograph may help.




When the round fires, the bullet and slide are accelerated in opposite directions at the same time. The slide grabs the barrel by the upper lugs, and drags it backward with it.

Note the engagement of the upper barrel lugs to the slide lugs.

If you look close, you can see the bones in the shooter's hand.

Note the position of the link, and the misalignment of the slide and frame at the rear. The slide has moved approximately .075 inch, and the base of the bullet is about an inch from the muzzle. At this point, the slide and barrel are still locked together horizontally.

Nominally...in the .45 caliber pistol...the slide moves 1/10th inch at bullet exit. In a 1911-pattern 9mm pistol...because the slide and barrel are about the same mass as the .45, and because the bullet is moving faster...the slide would likely move a little less at the point of bullet exit, but the difference would be very little. Maybe .010 inch or so if that much.

At 1/10th inch of rearward barrel and slide travel, the link just starts to tug on the barrel to draw it out of the slide. At .250 inch of travel, the barrel is completely linked down and the slide continues on its way.

 

[jeff-portnoy]

I really don't understand the question. If you mean how far back does the slide on a auto pistol have to come, the answer is that it must come back far enough to make sure the fired case ejects and the slide picks up the next cartridge when it moves forward.

If you mean how far must the slide and barrel of a locked breech pistol travel back together before unlocking, that is an issue involving both the gun design and the cartridge. There really is no fixed distance but, as a general answer, about 1/4-3/8 inch.

Jim

Surely I mean how far must the slide and barrel of a locked breech pistol travel back together before unlocking!

 

[jeff-portnoy]

This old fluroscope photograph may help.




When the round fires, the bullet and slide are accelerated in opposite directions at the same time. The slide grabs the barrel by the upper lugs, and drags it backward with it.

Note the engagement of the upper barrel lugs to the slide lugs.

If you look close, you can see the bones in the shooter's hand.

Note the position of the link, and the misalignment of the slide and frame at the rear. The slide has moved approximately .075 inch, and the base of the bullet is about an inch from the muzzle. At this point, the slide and barrel are still locked together horizontally.

Nominally...in the .45 caliber pistol...the slide moves 1/10th inch at bullet exit. In a 1911-pattern 9mm pistol...because the slide and barrel are about the same mass as the .45, and because the bullet is moving faster...the slide would likely move a little less at the point of bullet exit, but the difference would be very little. Maybe .010 inch or so if that much.

At 1/10th inch of rearward barrel and slide travel, the link just starts to tug on the barrel to draw it out of the slide. At .250 inch of travel, the barrel is completely linked down and the slide continues on its way.

Thank you very much pal.
Incredible picture!

 

[1911Tuner]

You're welcome, Jeff.

You'll also notice that the pistol is showing very little muzzle flip, if any. There's a clue there. If that had been a fixed-breech gun...like a revolver or a TC single-shot pistol...the muzzle would be a lot higher. We don't get much in the way of recoil with an autopistol until the slide impacts the frame...and by the time that happens, the bullet is about 20 yards downrange with the .45 cartridge...and a good bit farther with speedier rounds.

There are other, more subtle clues present.

Such as the way that the locked breech actually locks and it discredits the claims of the spring kinking with the standard guide rod arrangement.

Note how many coils of the recoil spring that aren't supported by the rod and the plug.

Look closely at the lug engagement and think about the forward drag being imposed on the barrel as the slide pulls it backward. The barrel lugs engage with the slide's lugs vertically...but it locks horizontally with the lugs in opposition under high shearing forces.

Finally, this photograph...probably taken in the 20s or earlier...pretty much blew Kuhnhausen's "Balanced Thrust Vector" description outta the water decades before he published it.

 

[jeff-portnoy]

So,...you mean Browning system "non-work" in theory, but it work practically?!

 

[1911Tuner]

No. I said that Kuhnhausen's description can't happen the way he describes.

 

[Jim K]

"Kuhnhausen's description can't happen the way he describes. "

+1

But recoil starts with a locked breech pistol at exactly the same time it starts with a blowback pistol, or a Mauser rifle, or a Brown Bess. Recoil begins when the bullet begins to move. Period.

Felt recoil, though, can vary, if the recoil force is spread out over time by moving parts, absorbed by the mass of the gun, or counteracted in some way (e.g., a muzzle brake).

Jim

 

[1911Tuner]

But recoil starts with a locked breech pistol at exactly the same time it starts with a blowback pistol, or a Mauser rifle, or a Brown Bess. Recoil begins when the bullet begins to move.

Yup.

Felt recoil, though, can vary, if the recoil force is spread out over time by moving parts, absorbed by the mass of the gun, or counteracted in some way.

The difference that I've had a little trouble convincing some people of is that...with an autopistol...they don't feel much in the way of recoil the way they do with a fixed-breech arm like a revolver because there's no solid connection between the gun and the frame, and thus there's no immediate transfer of the recoil impulse to the hand. The barrel and slide assembly is the gun. The frame is the gun mount and a housing for the controls.


90% of what we recognize as recoil in the auto is muzzle flip, and it comes from the slide impacting the frame. By the time that happens, the bullet is about 20 yards downrange, and the actual recoil generated by firing the cartridge is long since over.

 

[Patrick Gookin]

What's with the front sight? Was the blade too thin to be picked up in the photo? It almost looks like the top part of the slide raises up to a point near the front.

 

[1911Tuner]

What's with the front sight? Was the blade too thin to be picked up in the photo?

Yep. If the fluroscope will penetrate the frame and slide, it'll penetrate the front sight.

 

[1911Tuner]

This video also provides a strong clue to the function of the locked breech/short recoil operation. This one is 9mm, but I've seen the same demo done with a .45 caliber Glock

http://www.youtube.com/watch?v=Gw8sbb8eDjg

 

[Jim K]

A common "trick" with a Ruger .22 auto, which also can be held back because there is no sharp edge to cut the hand or thumb. Best not tried with a Colt hammerless auto; those have VERY sharp corners.

Jim

 

[1911Tuner]

Best not try it with any straight blowback larger than .22 rimfire or .25 Auto.