Seriously now, My Questions...........#1
First, I could try to dig out answers myself; that don't help anyone else-- I would like to learn from others. With our dial-up service if you hand me a website, it might take 5 minutes to get it.
Second, lots of the stuff I would like to know more about is technical. I'm not being a smart-ass by asking that stuff; I really don't have the answer.
Third, if my topic makes you want to ask something instead of answer, fire away! Maybe someone else knows if I don't (I probably won't).
Last, if I flat out don't know, then that's what I'll say, not drag it out with lengthy BS.
So, semi-auto firearms, pistols, are always said to require a locking means to keep the bolt closed until pressure drops to a low level. I say bull. The H&K VP70Z 9mm pistol has a FIXED barrel, fastened to the frame, with NO LOCKING MEANS. The slide can move freely at any time. The gun functions well, cases come out normal diameter, not bulged or anything like that. Guy at a gun show told me it's because of the very heavy slide; I believe that isn't true.
Do the Germans know some kind of F. M. or what? BTW, I once knew a guy who had a home-made pistol which worked same way, no locking means, in 9mm, shot like a charm.
Second, lots of the stuff I would like to know more about is technical. I'm not being a smart-ass by asking that stuff; I really don't have the answer.
Third, if my topic makes you want to ask something instead of answer, fire away! Maybe someone else knows if I don't (I probably won't).
Last, if I flat out don't know, then that's what I'll say, not drag it out with lengthy BS.
So, semi-auto firearms, pistols, are always said to require a locking means to keep the bolt closed until pressure drops to a low level. I say bull. The H&K VP70Z 9mm pistol has a FIXED barrel, fastened to the frame, with NO LOCKING MEANS. The slide can move freely at any time. The gun functions well, cases come out normal diameter, not bulged or anything like that. Guy at a gun show told me it's because of the very heavy slide; I believe that isn't true.
Do the Germans know some kind of F. M. or what? BTW, I once knew a guy who had a home-made pistol which worked same way, no locking means, in 9mm, shot like a charm.
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Was that a question or a statement?[:)] 0 -
SOMETHING keeps the action closed until pressures drop. It may be a locking mechanism, or a really heavy slide and a really stiff action spring. Some submachineguns fire open bolt- a heavy bolt, heavy spring. 0 -
Slide weight and recoil spring keep the action closed until pressure drops to a safe level. IIRC this is a blowback type action.
A rimfire firearm is a good exmple of this.0 -
For every action there is an equal but opposite reaction. If the bullet travels forward at 1000 feet per second then the (now) empty case will also travel at the same speed, but in the opposite direction. In this situation the disparity of weight between the bolt/slide assembly and the empty case is enormous, so much so that the speed of the case has slowed enough so that when the bullet exits the barrel, pressures will have dropped to a safe level. From an engineering standpoint you could do without locking the breech on even heavy caliber rifles, but I am guessing that the bolt on .30-06 rifle which uses no locking mechanisim would probably have to weigh something like 30-40 pounds in order to maintain safe pressures! 0 -
The HK VP70Z has a very heavy spring. If you've ever racked the slide on one you'd notice it is robust to say the least. I'm guessing it runs in the upper 20 pound area (26-28). The bullet is launched and pressure falling long before the case is out of the chamber. 0 -
That is a "blow back" action, commonly used for small caliber (9mm and smaller) pistols. Locked breech actions are generally used for larger caliber pistols. 
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quote:Originally posted by 11b6r
SOMETHING keeps the action closed until pressures drop. It may be a locking mechanism, or a really heavy slide and a really stiff action spring. Some submachineguns fire open bolt- a heavy bolt, heavy spring.
Increasing spring rate will at some point result in the blow-back force being insufficient to move the slide far enough to eject, just like the effect of too small a powder charge.
Theory I've heard is that weight of bolt and strength of spring affect primarily only the firing rate, if full-auto, or the speed of the bolt if semi-.
Open bolt firing eliminates a bit of moving guts, so it's pretty fast, compared to, say, M-16, which has to wait (a very short time) after the bolt is closed for hammer release and stroke to fire the round. Open bolt has good and bad points- eliminates "cook-offs", but brings possaibility of round exploding outside of chamber if chamber blocked, round misfeeds, etc.
Real interesting open bolt design is the Thompson SMG (original) which fired from an open bolt but had a movable firing pibn which was struck by a little hammer mounted in the front of the bolt and struck the front of the inside of the receiver as the bolt hit home. The hammer only moved less than 1/4 inch.0 -
quote:Originally posted by linthicum
Was that a question or a statement?[:)]
Like Jackie Gleason, I've got a BIIIG mouth. He admitted it, so do I. A bag of hot air, I need help like yours to deflate sometimes!0 -
The weight of the slide and recoil spring keep the bolt closed on a blow back type action.
http://en.wikipedia.org/wiki/Blowback_(arms) Read this.
Also the HK P7 is a delayed/retarded blowback Read this http://en.wikipedia.org/wiki/Heckler_&_Koch_P7
Other types of actions are recoil(Bowning A5) and gas operated(Rem 1100)0 -
you seem familiar...[:o)]
have you been here before?
Regardless, welcome.
Ben0 -
I have a VP70z - fun little gun. It is double action only BTW and has no hammer per se. I think this is due to the design of the VP70m, which is capable of 3 shot burst.
I've broken the gun down many times and it would be a simple matter to convert it to full-auto (uncontrolled) due to the design.
It does indeed have a very heavy slide and high presssure spring!
It is also a work of art!0 -
quote:Theory I've heard is that weight of bolt and strength of spring affect primarily only the firing rate, if full-auto, or the speed of the bolt if semi-.
This is true, but the slide and spring also absorb and effect the recoil energy, especially noticable in a pistol. In the case of the VP70 the firing rate is very fast in 3 round burst mode, but it is not a open bolt design. It is striker fired.0 -
video of vp70m being shot
http://www.youtube.com/watch?v=_W6XuqfQCl80 -
+1 Kristov! Excellent answer! ghs 0
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