Extruder Barell
Hi Guys, had a thought today regarding barells. There was a company here in Australia in the early 90’s making extruder, or tapered bore barells for the .22LR rimfire. The idea was that the bullet was squeezed down from .22 to .20 or to .17 calibre on exit. This increased velocity by some margin, due to the higher pressure from the extruding process upon firing. These barells where made by Myra gunshop in Broken hill Australia. How effective they were i dont know in rimfire, there was someone in a forum saying they werent accurate. They have sinced ceased trading, i think the inventor died a while back. I even read the Germans had developed the idea in WW2 for there anti tank guns. The idea is sound, and does work, but aparently much too expensive to be practical. Anyway enough of the history of the idea, my thinking is would the same principle work in a PCP rifle? I have read that some of the .25 guys are getting pretty much the same velocities with heavier pellets in .25 as we get in .22 with much lighter pellets. Aparently the greater surface area of a .25 V a .22 makes the .25 more efficient. So if it where possible to make/buy a .25 barell that tapered to .22, or .177 would it generate higher velocitie by building up more pressure? I dont think there would be any problems with the pellet swaging down in the bore. I have been kinda thinking of ways to experiment with this idea, but tapering a bore is a big problem. I was thinking to take an old shitty .177 barell and bore the breech end to 5.5 and taper a forcing cone like in a shotgun. Any body have an idea that this will or wont work? or how it could be done? Imagine a .25 40gr pellet swaged down to .177 fired at around 1000FPS,i think the sectional density and BC would be awsome ! Any idea’s would be most welcome !
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Sorry for jumping on your case. 😳 The BSA’s are hammer forged and thus have a taper but it is very, very slight.
My post was in partial answer to Muzzas origional post. The BSA narrel is tapered for its entire length, as was the Extruder barrel. I don’t know if there is any velocity correlation.
Dave
dmorley,
WTF is this? I’m getting the quote of Harry regarding the BSA rifles but I can’t figure out why you posted it here. Do you think that BSA barrels have anything remotely to do with the “extruder” idea? Seems like a weird way to bring back a dead post and not add anything relevent to anything!
Yrrah
(Login Yrrah)
YFOT I am not sure of availability in the USA ( I am in OZ ) February 1 2010, 8:56 PM
but the standard BSA Hornets in .22 cal are brilliant little rifles. They are not now presently being made by BSA as they have moved on to other models. Their barrels are really excellent and maybe, as they are hammer forged on a tapered mandrel, that continuous taper ( read full length choke ) and the exceptionally smooth bores have something to do with it. The taper is necessary to facilitate extraction of the mandrel I understand.
Not too many of these rifles seem to be released in the trade market.
You can get a rifle like mine from John Bowkett in the UK. The person to talk with here is Tony who has three or four of them and could fill you in as to how he went about it. … Thank you for your interest and response, Kind regards, Harry.
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here ya go a lil info on the .223 round and its pressures as u stated 61000 psi
i was using a lowball off the top of my head answer
but i know that with some of my hot loads for my .223 if i dont use 5.56 brass and i use .223 brass i will exceed the max CUP (copper units pressure)
so anyways off topic here lol
yeah an airgun has WAY less pressure than does a powderburner
“”” There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56×45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56×45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat,”””
It’s mostly because of the shoulder shape and the larger ball ammo they use… A M885 (armor piercing) has an 80 grain bullet that is almost a full caliber longer than the 60 grain ball I reload with. The M885 ammo won’t even load into my 223 target rifle… A standard 223 round will make a sound with a shake or two, the military cartridge has no extra room inside… (It may not be called 885, it may be 855)…
If I seat my ball too deep on my 223 rounds I can elevate the chamber pressure to the danger zone… This would be dangerous and inaccurate since the ball would be too far away from the throat of the rifling…
Don’t do it Jerry pussy is way better 😆
Yeah no such thing as stupid questions. Only stupid answers. Not saying the answers here where stupid.
Heee’s baaackkk!!!!
A little off topic but I wanted to understand SAAMI vs NATO in 223. I checked Wikipedia and its got a good description: http://en.wikipedia.org/wiki/5.56x45mm_NATO#5.56mm_NATO_versus_.223_Remington
Your right Jerry, there are experts on this Forum, part of the reason i love it so much !
And stupid me, i seeked those experts and there opinions by starting this thread, then said there where no experts ! yes i have contradicted earlier posts ! Some of us dont know the inner workings of pressure and air and bullets and slugs etc etc, thats why we ask some dumb questions sometimes.
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here ya go a lil info on the .223 round and its pressures as u stated 61000 psi
i was using a lowball off the top of my head answer
but i know that with some of my hot loads for my .223 if i dont use 5.56 brass and i use .223 brass i will exceed the max CUP (copper units pressure)
so anyways off topic here lol
yeah an airgun has WAY less pressure than does a powderburner
“”” There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56×45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56×45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat,”””
Well, after reading Muzza’s reply to my rant, I figured I’d go a flaming. Seeing the rest of the replies, I realize that won’t be required. I will have to apologize to my 5th grade tutor as I still can’t spell despite her best efforts. 😆
Crow, I don’t know what the average PB breech pressure is but I was just reading about a new .338 that runs at 61,000 psi and apparently, thats about normal! That gun needed a sturdier breech not because the pressure was high but because there was more area subject to that pressure. The point though (as you make clear) is that airguns and PBs run at vastly different psi. (And when you take duration, max impulse, min impulse, area under the curve into account… we’re talking two hugely different animals)
Muzza,
I don’t have a problem with questions. Take a look at my original reply. I do take exception to the idea that there are no experts here. There are a lot of experts here! That’s why people come here and ask questions about their guns. They either get an expert answer or collective expertise. Otherwise, they could just go to some other forum and kick their question around with a bunch of people unable to answer.
I’ve told many of my soldiers that The only stupid question is one not asked, But I also Told them that if your asking the question then you must have no knowledge or a limited knowledge of the subject so don’t get mad at the answer. [/b]
Look guys I only asked a question about tapered bores and pellets, not solid slugs. I figured a waisted diabolo pellet would swag slot easier than a bullet. If it can’t be done fine. But water and hoses were mentioned and there was a reply that constriction would raise the velocity of the water. I then asked if the same princeple would work in a valve. Forget the tapered barell, would a tapered valve increase the velocity of the air? Would that mean it would be a more effecient design, ie using less air for a given velocity? I’m just asking a question, not stating a fact. A tapered valve I might be able to make.
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NP Jerry,
I just wondered lf a correlation was at all possible. Maybe if set up as a pressure barrel with strain gauges at the leade and the muzzle. BSA Vs.
unchoked LW or something.
Dave