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All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Big Bore AirGun Gate => Topic started by: JonnyReb on March 31, 2011, 09:11:08 PM
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For those of you who have shot a 201, i'm wondering if the plastic sleeve you see on this 9mm is required for shooting? I have not seen this sleeve on other korean guns but it's a great idea and surely minimizes air loss. Does it come with the 202? I know the .45 doesn't use them(sam yang), at least the one i had didn't come with one..
I can't help but want to have some copies of this made in other, less brittle materials and they could easily be converted to hold shot, a pocketful of these sleeves preloaded with shot and sept 1st dove season may take on a whole nuther aspect, sitting in the side field beside the house watching over my garden. Preloaded with slugs for coyote.. a very good design, i just want more of them, anyone else use these?
(http://i195.photobucket.com/albums/z252/xxjonnyrebxx/004-3.jpg)
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I don't have one on my 202, but I'd like to, looks like a good bit of kit to me
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Makes me wonder how much this sleeve has to do with the 201 reportably being a bit stronger than the 202, the breech side of the exhaust port has notches for the sleeve to fit in, it does appear it was from the factory although i can find nothing online to back that up. ???
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The 202 has the same notch, wander is they found out that wasn't actually necessary, since the 909 has the same basic sistem but no sleve ?
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I'll chrony it both ways, might take me a few days but i'll post what i find, if it adds to the velocity i'll have a bunch of these sleeves made and you can try one out. J
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yep, I'll definatly take one :)
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Jeff,
So you slip the loose piece in between the barrel breech that is on the right, and the transfer port that is on the left, and then slip the brass sleeve back to the left and over top of the o-ring to seal it all up?
So is that loose piece just a transfer port extension, or it sounds like you could load something into it so long as it was not too large to pass into the breech when you fired it.
Is the loose piece aluminum, machined, die cast? Can you tell?
Lloyd
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Hi Lloyd, yup you got it, it slides into the barrel end first, just enough to then drop into the notch you can see on the left transfer port side. Once it's in place it really doesn't have much side to side play, it will only come out by picking it up from the receiver side. The brass sleeve does slide to the left and seals it all up. The other korean guns i've seen did not have this but the notch on the transfer port side does indicate that it was a factory design, and obviously one shared by the 201 and 202 both. This sleeve is cheap plastic. Brass, delrin or pcv all seem like better materials to consider for future sleeves.
As the 201 was originally a 9mm smoothbore shotgun later converted to .357 with a rifled barrel, i can't help but to wonder if this sleeve was the "hull" to hold a preloaded pellet shot load between two wads of some sort. Tom Gaylord reported what was to him, in 2000? or so,the most astounding thing he had yet seen in pcp development when this air shotty came out and he figured almost 260ftlbs of energy from the 201 shotgun with whatever weight of lead shot he loaded into it during his testing. I know thats paltry compared to some modern bigbores but not many years ago it was something that had not been seen since the bigbores of the 1700's, at least not here in the US. They had to have some way of loading the shot and i'll bet this sleeve is it. Whether or not it adds to velocity of a slug in this rifled barrel remains to be seen but i'll assume there will be some improvement in power. If it's worth doing i'll have some made but with an even tighter tolerance to reduce more leakage. I'll have to try it as a shotgun also, but i'm assuming the rifling and lack of a choke will limit me to close distances. I have seen the smoothbore barrels for this gun sold before but they are quite hard to come across now.
I'll let you know what i find and maybe in the meantime someone will verify the purpose of the sleeve. Jeff
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Seems to me that any space that can be filled inside of the sleeve without slowing airflow will allow more push on slug. Limits expansion space of air.
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Your almost certainly right and thats kinda what i'm counting on when i say it should help. Also the o rings on the gun that are covered by the sliding brass sleeve probably don't seal 100% of the air, it is just to imprecise a device to work that efficiently i think. I'll test those seals with babypowder or something to see it there is loss there, and to see if the sleeve minimizes it. Even if this particular sleeve doesn't make a huge difference, one of tighter tolerance would and it's not to hard for me to envision a new design which could be more permenantly installed with o rings to seal and a locking, airtight port with which to load by. It would no longer require the brass sliding breech at all and could be designed much more airtight. Another version with no port would allow the gun to be used as a muzzleloader for the states that don't allow breechloading airguns for biggame, but do allow muzzleloaders. Now i just need a lathe... ;D
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https://www.pyramydair.com/blog/2005/10/air-shotguns-part-2-the-fire-201/ (https://www.pyramydair.com/blog/2005/10/air-shotguns-part-2-the-fire-201/)
Well here is the answer, it is indeed for the shotgun version of this gun. I'll see how it does with a rifle. J
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Jeff,
OK, after reading what you have written, and Tom Gaylord's article, I understand. With a little bit of rework, the setup should be able to be made air-tight and it should work very efficiently. As tkerrigan said, a main function of the sleeve is to limit unproductive expansion of the air behind the bullet/shot. But with the barrel being that short, it might not show a big difference in velocity with or without the sleeve, but with a longer barrel the difference should be quite noticeable.
If that barrel is only 21" and the gun is VERY loud, a lot of energy is being wasted. A much longer smooth bore barrel could work very well. If you can collect some shot data (I have a list of required input parameters) I could run a simulation with a longer barrel and see what might happen. Think of it this way: the valve is capable of releasing a certain number of fpe, but because of the nature of the expanding air, a short barrel doesn't give the bullet enough time to accelerate and therefore much of the energy is dumped as a loud blast out the end of the barrel.
But you know somebody out there has already put a nice long smooth bore on this and is shooting those doves!
Lloyd
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No doubt about it, a long shotgun barrel would bother me not in the least and actually i would prefer it for more reasons than just power increase, although i would of course welcome that ;D The weight wouldn't matter as getting those factory sights off would shrink some oz. and i'll bet with a proper choke it would shoot great. The power level would allow for some additional shot to be loaded as well. That would be a very cool conversion, although i may have to get another 9mm because i surely want one with a rifled barrel too. Or, the shotgun might really be better applied to a .44 caliber or larger just for all the additional weight you could shoot. Sounds like another good project doesn't it? ;)
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Thanks for the correction John, i've noticed you seem to know a LOT about the history of the korean guns and i sure appreciate your input, Did they use a different valve or just rework the old design? J