mice - is 450 fps/ .177/ 5.1 gr steel bb enough?
- Thread starter Texan Scott
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Crashbox
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I find this to be a very interesting thread. Never even thought of some of the methods, e.g., blow gun, in such a situation.
One thing I will probably NEVER do: back in the 1960's my brother and I knew this family a couple of blocks down the street. The father saw a rat one day in their house and took a .357 Magnum to it. Not sure if the dad went to jail for that one (it was illegal even back then)...
I like the idea of using other, SAFER methods for rodent disposal.
One thing I will probably NEVER do: back in the 1960's my brother and I knew this family a couple of blocks down the street. The father saw a rat one day in their house and took a .357 Magnum to it. Not sure if the dad went to jail for that one (it was illegal even back then)...
I like the idea of using other, SAFER methods for rodent disposal.
rcmodel
Member in memoriam
Tell me about it!!
My next door neighbor used to be a parole officer for the county.
So one night, he goes to take out the garbage, and a possum ran in his garage while he had the door up.
Six shots from his .38 Special later???
His garage wall had five holes in it, and so did the neighbors living room wall on that side of his house!!
We never did figure out where shot #6 went??
The possum got away without a scratch as far as I could tell!
rc
John: I didn't mean quieter as in muzzle blast, I mean quieter power plant, like pull the trigger and it's virtually silent because the piston did not slam into the breech. Heavier pellets reduce piston slam, they also reduce dieseling. I'm sure I'll get argued on that one, but I call it like I see it. I've never broken a spring but I imagine cheap over tempered steel is the problem. Yes dieseling would send a harsher shock thru it, but if heavier pellets are used then less dieseling so.... Now guns with no real transfer port like a B3 is a different story, so it depends on the gun. I suppose guns of yesteryear had both crummy springs and no real port which I imagine is how this thought came to become "fact", kinda like the 6" rule 
rondog: Not for shooting mice, for owning it period. Check local laws b4 ordering your "Jivaro Survival Blowgun" from the back of a comic book! Police in my town were anal and bored. Got popped many times for airguns, also illegal. Fireworks, sling shots, too much to name. I was a busy kid, Dennis the Menace I suppose, but fun!
rondog: Not for shooting mice, for owning it period. Check local laws b4 ordering your "Jivaro Survival Blowgun" from the back of a comic book! Police in my town were anal and bored. Got popped many times for airguns, also illegal. Fireworks, sling shots, too much to name. I was a busy kid, Dennis the Menace I suppose, but fun!
Well, it will be quieter for that reason too, in addition to eliminating the muzzle discharge noise.
The added resistance stops the piston earlier than normal and, it is my understanding, causes a more abrupt rebound which can be hard on the spring.
In the really powerful sporters, it's probably less of an issue because the springs tend to be very robust in those guns. But especially in older guns or guns that aren't as powerful, using very heavy pellets can lead to early spring failure.
Do you mean that dieseling stops faster when heavy pellets are used?
Obviously, more resistance means higher pressure and that, just as obviously, means that dieseling is more likely to occur since dieseling is directly related to pressure.
HOWEVER, there's generally only a limited amount of "stuff" in the chamber to ignite in the dieseling process, and the use of heavy pellets will tend to burn that material out of the chamber. That will eventually (after several shots) result in reduced dieseling when there's no more "stuff" to ignite.
You sure like to call me out on everything don't you John....
For blocking the port I'd hardly call a soft stop on air harsher than hitting the breech which would send a shockwave up the spring.
The heavy pellet this goes like this (in my mind). And keep in mind that this varies on the guns design. The heavier pellet holds the pressure longer reducing piston impact on the breech. If I have a freshly oiled gun the dieseling is less violent with heavy pellets, the heavier they are the greater the effect. It will diesel for more shots since each firing is less powerful, but better to have 5 low powered than 2-3 violent ones. Now, once violent (loud) dieseling has stopped with heavy pellets I can shoot a light pellet and it will diesel again which tells me the pressure was higher than with the heavy. I don't believe this has to do with port pressure, but pressure at the piston face which increases dramatically the closer the piston is to the breech or the force at which it hits. Lighter pellets allow the piston to hit harder therefore they diesel more. If the dieseling were in the transfer port alone then yes a heavier pellet would be worse, but if it were in the port alone I doubt it would be a problem. Another item to show dieseling is all about the piston face and not the pellet, you can take a gun that has stopped dieseling with light pellets, dry fire it and it will diesel again. It does so because you sent pressure at the piston face even higher than before because it hit harder. Dieseling in the port would be impossible without a pellet. All this tells me that piston impact is what causes dieseling just like clapping your hands harder = louder. Another point is guns that I've increased the compression ratio diesel less. I know that doesn't sound right, but it reduces piston impact and thus hot spots that ignite the oil, kinda like how a poorly designed cyl head in a car will ping or diesel before a well designed one will, even when the better head is higher compression. It's not the same principles, but being designed better is the key.
Now like I mentioned before it's all about the design of the gun. The relation between the bore and stroke is a factor, the smaller the bore the more likely it will diesel, but it's not as harsh on the spring when it does. Piston speed is a factor, a heavier spring increasing piston speed also increases dieseling. If you have a gun like a cheap chinese model with a large diameter but very short port then a heavier pellet will cause a bump in pressure and also put more dieseling pressure on the piston. And due to the small volume of the port the pellet starts moving sooner in those cheap guns than with a modern gun so pellet weight is an even bigger factor because the lighter pellet has moved sooner thus decreasing pressure. Since those cheap guns don't usually have nearly the power, and no real volume to the port it makes all the difference and the two guns cannot be compared.
If you have a gun where the piston doesn't hit the breech then that too will change things and the lighter pellet will be slightly better at reducing dieseling (in my mind). But since most all efficient springers have pistons that hit the breech, and most all guns sold are like that, then my idea of what's happening covers most all modern springers. That's my story and I'm stickin to it
I urge you to experiment, including plugging the barrel to simulate the heaviest pellet.
For blocking the port I'd hardly call a soft stop on air harsher than hitting the breech which would send a shockwave up the spring.
The heavy pellet this goes like this (in my mind). And keep in mind that this varies on the guns design. The heavier pellet holds the pressure longer reducing piston impact on the breech. If I have a freshly oiled gun the dieseling is less violent with heavy pellets, the heavier they are the greater the effect. It will diesel for more shots since each firing is less powerful, but better to have 5 low powered than 2-3 violent ones. Now, once violent (loud) dieseling has stopped with heavy pellets I can shoot a light pellet and it will diesel again which tells me the pressure was higher than with the heavy. I don't believe this has to do with port pressure, but pressure at the piston face which increases dramatically the closer the piston is to the breech or the force at which it hits. Lighter pellets allow the piston to hit harder therefore they diesel more. If the dieseling were in the transfer port alone then yes a heavier pellet would be worse, but if it were in the port alone I doubt it would be a problem. Another item to show dieseling is all about the piston face and not the pellet, you can take a gun that has stopped dieseling with light pellets, dry fire it and it will diesel again. It does so because you sent pressure at the piston face even higher than before because it hit harder. Dieseling in the port would be impossible without a pellet. All this tells me that piston impact is what causes dieseling just like clapping your hands harder = louder. Another point is guns that I've increased the compression ratio diesel less. I know that doesn't sound right, but it reduces piston impact and thus hot spots that ignite the oil, kinda like how a poorly designed cyl head in a car will ping or diesel before a well designed one will, even when the better head is higher compression. It's not the same principles, but being designed better is the key.
Now like I mentioned before it's all about the design of the gun. The relation between the bore and stroke is a factor, the smaller the bore the more likely it will diesel, but it's not as harsh on the spring when it does. Piston speed is a factor, a heavier spring increasing piston speed also increases dieseling. If you have a gun like a cheap chinese model with a large diameter but very short port then a heavier pellet will cause a bump in pressure and also put more dieseling pressure on the piston. And due to the small volume of the port the pellet starts moving sooner in those cheap guns than with a modern gun so pellet weight is an even bigger factor because the lighter pellet has moved sooner thus decreasing pressure. Since those cheap guns don't usually have nearly the power, and no real volume to the port it makes all the difference and the two guns cannot be compared.
If you have a gun where the piston doesn't hit the breech then that too will change things and the lighter pellet will be slightly better at reducing dieseling (in my mind). But since most all efficient springers have pistons that hit the breech, and most all guns sold are like that, then my idea of what's happening covers most all modern springers. That's my story and I'm stickin to it
I urge you to experiment, including plugging the barrel to simulate the heaviest pellet.
Being questioned is a readily forseeable consequence of making public assertions.
Seriously, if everyone had exactly the same opinions and knowledge/experience base, what would be the point of these forums? There would be no need for them to exist.
The way I look at it, is if you say something that doesn't align with my knowledge/experience base, I have two options.
1. I can ignore it, in which case we both go on as before, neither of us knowing any more than we did before.
Or
2. I can ask about it and create the potential for one or both of us to learn something new through the resulting exchange.
I don't believe normal operation involves the piston hitting the breech with significant force. Normal operation is for the air cushion to decelerate the piston significantly, before it hits the breech. Perhaps even stopping before it hits. Plugging the breech, or dramatically increasing the bore resistance as with very heavy projectiles causes a more abrupt piston rebound that wouldn't normally be experienced except with dieseling, or perhaps with a dryfire when there is a significant impact between the piston and breechface.
I like your discussion about dieseling due to isolated pressure "hot spots" between the breechface and piston face as opposed to having the entire chamber reach a high enough pressure to diesel. It's hard for me to visualize having significantly different areas of pressure in a single, relatively small, chamber. I will have to think about that for awhile.
First off I believe (fully) that most of these modern high powered guns do impact the breech, and hard. If they didn't there wouldn't be a scope problem, but there is a severe scope problem. If you block the breech so the air stops the piston, surprise, no impact shock. Instead you get a normally soft recoil, and an equally soft reverse recoil that will never hurt a scope.
So, if that is true then having a piston slam into the breech can cause spots to hit higher pressures, maybe the center of the seal or the groove, but also consider any air trapped between the flat parts of the seal and breech that have just been smashed at insane pressures which also shoot off into the center or groove areas to further bump their pressures. One way or another the pressure is skyrocketing in there. Now consider that a little ignition in one spot can bump pressure to cause a cascading effect to light everything up. This is why I do what I can to reduce piston impact. If I didn't mention it before, I've also never broken a scope and I fully believe this is why.
Block a breech and it'll make sense when you feel the difference.
So, if that is true then having a piston slam into the breech can cause spots to hit higher pressures, maybe the center of the seal or the groove, but also consider any air trapped between the flat parts of the seal and breech that have just been smashed at insane pressures which also shoot off into the center or groove areas to further bump their pressures. One way or another the pressure is skyrocketing in there. Now consider that a little ignition in one spot can bump pressure to cause a cascading effect to light everything up. This is why I do what I can to reduce piston impact. If I didn't mention it before, I've also never broken a scope and I fully believe this is why.
Block a breech and it'll make sense when you feel the difference.
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