PDA

View Full Version : Hayabusa .457 Hits 550 FPE



rsterne
12-05-2014, 07:42 PM
http://i378.photobucket.com/albums/oo221/rsterne/Hayabusa%20PCP/HayabusaLogo.jpg (http://s378.photobucket.com/user/rsterne/media/Hayabusa%20PCP/HayabusaLogo.jpg.html)

Today was quite a day.... After a couple of years of planning and a year of work, I shot my Hayabusa .457 for the first time today, and saw over 550 FPE.... I tested three kinds of ammo, found the maximum that the gun would do at 3600 psi with all three, and found two great shot strings.... The bullets used were a 143 gr. roundball, and two Lee bullets, a 216 gr. RN and a 336 gr. FN.... In order to find the velocity plateau I had to use the two 3" hammer springs like I did on the .410 shotgun, and here are the maxed out results....

143 gr. RB - 1101 fps (385 FPE)
216 gr. RN - 993 fps (473 FPE)
336 gr. FN - 859 fps (551 FPE)

Needless to say, all the work and frustration has paid off and I've got a pretty big smile right now.... I put the 4.5" long 0.072" wire spring back in and shot the following strings....

http://i378.photobucket.com/albums/oo221/rsterne/Hayabusa%20PCP/Hayabusa457_zps4c23b7a5.jpg (http://s378.photobucket.com/user/rsterne/media/Hayabusa%20PCP/Hayabusa457_zps4c23b7a5.jpg.html)

With the spring just shy of coil bind the roundball showed the first shot fastest at 1070 fps.... The 216 gr. RN had the 2nd shot fastest at 960 fps.... Both bullets had 5 shots before falling more than 4% below the peak.... With the 336 gr. FN bullet I got a very nice 7 shot string peaking at 815 fps (496 FPE).... That string averaged 800 fps (477 FPE) with an efficiency of 0.96 FPE/CI.... I then backed the preload down a turn and shot another string with the 216 gr. RN and got 8 shots peaking at 929 fps (414 FPE) and averaging 913 fps (400 FPE) with an efficiency of 0.99 FPE/CI from 3600 psi down to 2400....
To say I'm pleased with this performance is an understatement.... I was hoping this gun would break 500 FPE, I never though it would break 550, nor did I think it would give me 8 shots at 400 FPE on a fill.... Time to just bask in the glow of satisfaction for a while.... I need a break.... and a drink....

Bob

longbow
12-05-2014, 09:08 PM
Maybe I missed something earlier on in a post but do you have pictures of this gun?

Custom build? Modified? Details? Tell me more!

Longbow

rsterne
12-05-2014, 10:47 PM
Custom build, been through at least three major variants over the last 4 years.... Started life as a .22 and .25 cal regulated PCP.... Progressed to an unregulated PCP in .224, .257, .308 and .357 cal.... The Mk.3 version is a .410 shotgun and .457 rifle, unregulated, running at 3600 psi.... Here is the .410 shotgun, the .457 rifle is identical, just a longer barrel and a scope....

http://i378.photobucket.com/albums/oo221/rsterne/Hayabusa%20PCP/Hayabusa410Shotgun_zpsfb2626a8.jpg (http://s378.photobucket.com/user/rsterne/media/Hayabusa%20PCP/Hayabusa410Shotgun_zpsfb2626a8.jpg.html)

It's kind of my Lego project.... I still have at least one more variation to build, the Mk.2 is going to get a 7mm barrel this winter....

Bob

longbow
12-06-2014, 12:18 PM
Very nice! Did you do the work?

Is it custom built from scratch or assembled from available "bits"?

I am still wanting a mid to large bore PCP... something likely .357 cal. to .45 cal. but the cost is a bit much so for now I am day dreaming. And I am talking total cost of gun, compressor, tank(s).

Longbow

rsterne
12-06-2014, 12:55 PM
I bought the stock (then cut it) and trigger from a Marauder, and the tank came from Best Fittings in England (250 bar, 500 cc), the .410 shotgun barrel (shown) is from an old bolt action Mossberg, while the .457 rifle barrel is a hammer forged blank from TJ's.... All the rest of the components (except screws and springs and the gauge) I made....

Bob

longbow
12-06-2014, 05:48 PM
Nice work!

Do you have a valve design that you built or did you design and make your own valve?

Same question about your breech mechanism. Did you design and build it or build from an existing design?

I have toyed with making a PCP rifle myself but I really need a small milling machine to take that on. I might get away with doing all the work in my lathe but I suspect it would be difficult and time consuming. Also, I tend to take on too many things and wind up part way through several projects with none completed. I don't think I need another one right now!

Longbow

rsterne
12-06-2014, 06:39 PM
I designed and made my own breeches and valves.... I use an Atlas Lathe with a Milling Attachment....

Bob

longbow
12-07-2014, 11:21 AM
Well, if I can get time then maybe there is hope for me yet. I have a small Craftsman (Atlas) lathe. It is well worn and needs some TLC to put it back into good shape but nothing major. Mostly the compound rest and cross slide screws are badly worn and have a lot of slop.

I have the vertical top slide (milling attachment) as well though it is not very rigid so light cuts only!

Is there a source(s) of design info for valves? I mean for basic sizing, type and spring rates? I have looked some but so far haven't found any specifics.

Thanks,
Longbow

rsterne
12-07-2014, 01:37 PM
Not that I am aware of, but I can tell you my opinions.... Work backwards from the caliber.... Use a barrel port that is 75% of that, if you go larger you may damage the pellets on loading.... Make the transfer port and valve exhaust port the same diameter, and as short as practical.... The throat of the valve needs to be slightly larger, so that the area (after subtracting the stem area) is at least the same area as the porting, and 10% larger will help efficiency, if not power.... Materials will depend on the pressures and diameters involved, with Delrin being the best choice for most PCPs, but PEEK required for high pressures combined with large valve throats, as the total forces are so great they can extrude the Delrin into the throat area.... You only need enough valve spring to hold the valve closed for filling, the air pressure does most of the work.... The bigger you go on the valve, the heavier the hammer you will need, with increased travel and a stronger hammer spring....

Bob

longbow
12-09-2014, 08:38 PM
I have a few projects to get out of the way before I even consider making a PCP rifle. Even then, I might be a bit out of my league. I will have to do some research for sure then decide If I want to tackle it or just buy one. Currently the "buy one" option is not likely and not just because of the cost of the gun, it is the peripheral equipment that is required along with the gun that adds to the cost as I am sure you know. Once that is all bought then of course it is a lifetime investment (or long time anyway).

We'll see how it all goes in the next few months.

Thanks,
Longbow