GTA
General Discussion To Gateway To Airguns => The Shop => : gunsup0331 July 01, 2008, 05:11:40 PM
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I noticed one of the machinist-type members mentioning a barrel choke device? I believe it was Fix.
I have searched this topic and havent found anything educational will someone plz explain to this n00b
how an attachable part can choke the barrel (make it smaller ID, right?)
thanks!
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Hey Fix, thats pretty neat. I may have to put a choke on my muzzle brake when i make one for my Storm XT.
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Fix, by your statement " brass muzzle thats heat shrunk on the end of the barrel " it sounds like you're saying that brass shrinks when heated. However, my limited knowlege suggests that what you actually meant, is that the ID of the brake is cut slightly smaller than the OD of the muzzle, you then heat the brake to expand the ID, slide it on the muzzle , and ,when it cools , it shrinks , thereby squeezing the muzzle causing a choke. Am I correct with this process? If not, please explain where I went wrong Thanks, JR.
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Choking Barrels?? Hey Folks,, Tim here!! I have been researching this subject dilagently for a couple of months now. With the help from a couple of my most advanced in the airgun world Friends, I am pretty close now to being able to choke brls. in a proffesional manner. Many of those that know me affectionatly refer to me as "Chopper Tim"LOL!! I have learned how to "chop" brls. & re-crown them with thus far exellent results. I will soon be able to provide a nice "Choke" as well. Stay tuned to this "Bat Channel"!! Tim.
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Wow i had this idea a while back but i didnt know a brass collar could actually put enough pressure --><-- like this to contract a steel barrel. Very cool! might be giving something like this a shot in the future. I love reading your technical posts Fix (even though i have no means to do some of the things u do(http://../jscripts/tiny_mce/plugins/emotions/images/smiley-cry.gif)) keep it up!
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Being a noob as well, can someone explain in layman terms what chocking the barrel actually does for the pellet/speed/accuracy?
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i found an article that explains it ted here is the link
http://www.airhog.com/airblog/2006/08/what-is-choked-barrel-and-why-do-we.html
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It takes ALOT of preasure to choke a brl. Tenths of thousanths can make a differance. Kinda made me feel good to read that link,, not a "true choke" ,,,,, but,, a constriction caused by the "pinching" of the doves on the end of the brl. (I did say that before!!LOL!!) My new "choke blocks" are being made. This "Red Neck Chopper" is going high tek!!!!!! Bahwahanna,, (Roger) We are gonna "choke" them brls. my Friend!! Unlike my "Chopping" & re-crown methods that made Gene& Mr Bob cringe!! (Did pass Genes "Q tip test),,, Lord in front of about 30 people!!LOL!! My "Choke Blocks" are being made by a profesional,, you guys will be proud!! Stay tuned,,,,, Tim.
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Hi Timmy I found a tool that will choke barrels it's a nicro press tool that you use in the boat ind. to make shrouds for holding masts up. they come in 2 types a type that looks like a huge bolt cutter I made one from a bolt cutter once and the type in my pictures I just happened to have I tried it on some old cutoff barrel tips and it works fine also I was thinking of the swage tool that you use for putting on ends on hi pressure hoses like pressure washers hydraulic hose's ect. what do you think howie PS I don't think this would be very hard to make this type of press.
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No mentioned was made and just in case someone wants to make a swag tool like Howie's. The hex head cap screws in the photo are grade 8. Any lesser grade would probably break before sufficient pressure is applied.
Mike
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I just choked my fast deer and now it doesn't do as good with daisy precision max , as before but it now stack's the CHP and the RWS diabolo basic , I have other guns I'll use up the daisy's up in like my TF 41 they shoot very good int it. The Daisy's don't hold as tight a group as before just a dime size hole but the other pellets stack one on top of the other 4 rds. one ragged 1/4inch hole. I'll keep it chocked. howie, I'm sure the bolts are grade 8 or 9 you can get them in the depot the steel bars are 3/4 x 3/4 inch.you would make the hole close to the dia of the barrel if you notice the steel bar is counter sunk on both sides this will give you more pressure at the place where it compresses the barrel . The last time a made one , I sandwiched a piece of metal in between the 2 bars and when I drilled the hole . This way it left a space to squeeze the fitting tight, after you take out the temporary piece of metal for making the hole.howie This was a good rifle to try it on since it doesn't have any front sight and has a muzzle break if it didn't turn out good I could just cut it off and re crown the barrel and it would be back to where I started just 2 inches shorter but that wouldn't hurt the deer my other deer was made into a carbine and it shoots great.
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Thanx for all the info really helpfull guys. Keep it coming!
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I think you have a good thing going here . Are you checking how much you are choking the barrel . I just went through this with my big bore and the last 2-3 inches are choked down to .357 which means I can use regular 357 rifle bullets that measure .358 - .359 as long as they are a soft lead and depending on weather they are ribbed wad cutters or not that will allow the lead to fill in the rifling groves or not. You could come up with some very accurate guns if you measure the pellet skirts and the barrel diameters . And FPS would increase as well with a good sealing pellet .From what I have been told that 1 -2 thousands is what powder burner re loaders go for . Marvin
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The only to check the id of a barrel is to slug it that means pushing a lead slug or casting a lead slug in the barrel and miking the slug I would think you would need to make a slug at the chamber end and a slug after you push the slug through the barrel to get a true difference of dia. of the 2 slugs.howie
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Thats a neat tool but when you slug a barrel you are measuring the groves not the lands.I don't know which is more important in a air rifle but in a fire arm it helps for getting the best bullet dia.
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Fix knows what he is talking about . I used the telescoping gauge on my big bore . Then as I said you know the basic bore and you can go 1 -2 thousands of a inch larger. That is how many people do it. I doughted at first my self but it is a formula they have used for years. My .177 CPH 10.5 mic .179 on the head and .180 on the skrit . I once saw a list of pellet sizes on some ones site but I do not know were. After I measured mine I then took a bullet of .358 that was tapered and pushed it in the muzzle . Then I pulled it out and it measured .357 on the smooth sides so now I had two measurements the same. The extra thousands to two thousands is what compress in to the groves. If you do not do some form of measurement you risk a injury to your self and any one around you . The energy has to go some were and if you shrink the barrel to much the weakest link goes up in smoke . Marvin
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We are talking about air rifles here how much pressure do you think is in a barrel when you fire a air rifle the amount of air is what is in the chamber and barrel if the end of the barrel was totaly shout all it could do is to push back the piston since it is held against the air port by the spring it would have to puch the piston back their is no other place for the air to go execpt back where it started from if it had the pressure to recock the gun is doubtful.