GTA
All Springer/NP/PCP Air Gun Discussion General => Projectiles => Boolit and Pellet Casting => Topic started by: Nvreloader on March 25, 2019, 02:43:24 PM
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Guys
Here is some interesting info for the swaging of AG pellets.
Food for thought.............. on pellet skirt thickness/psi,
http://www.corbins.com/pellets.htm (http://www.corbins.com/pellets.htm)
I do believe that casting would be better on the funds, than swaging..........IMHO
Thoughts or suggestions.............
Tia,
Don
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I would call those a skirted bullet, but some would call them a slug, or pellet.... They are definitely NOT a Diabolo pellet design like the NOEs.... Nor are they a conventional cast bullet like a 257420.... They occupy a space in between, similar to some of the NSA cup base "slugs", which of course are made in Corbin dies.... Nick does an excellent job with his swaged bullets, and is in the process of setting up his new automated swaging machine which will drastically reduce their cost to somewhere around the price of commercially available pellets.... Getting set up for swaging is not cheap, and you need dies for every caliber change (although you can change the weight by adjusting the length)…. You produce one bullet/slug/pellet at a time, but once you get the die adjusted, and find out what weight/length to cut each piece of lead wire, at least in theory you should be producing extremely consistent weights, with little need for inspection of each one.... They should be more consistent than cast bullets, but slower to produce.... While you could size them down 0.001" or so, generally any diameter change needs new dies....
Bob
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Bob
What are your thoughts on the pellet skirt thinness -vs- high psi values of PCP's.
with the blowing out of the skirts, that Corbin is posting?
And I have been having problems with LL, with very bad cork screwing pellets at 25 yds,
I could see the pellets spiraling in about a 12-18" circle before impact, 10 shot groups were 12-18" dia range.
They would start out and spiral in a left hand arc, with the first one about 8-10" to the low left,
then each next shot would start would land another 2-3" a little lower left and down etc,
finishing in a 18+" circle around the POA.
Seeing I had a problem, ::) LoL,
I tore LL down and found this, and the center preload adjustment screw of the SSG,
was set at max power enough, (no space at the end of the hammer),
to allow the hammer to hold open the poppet, (very light spring).
As I had to cock the rifle to allow it to fill the tank, and was only getting less than 20 rds,
per tank filled to 3000 psi and reg set point @ 1500 psi, 80 cc plenum etc.
I thought, I had both adjustment screws tighten down enough, but I guess I didn't,
I now have a lead BB in each grub screw hold to hold the screw adjustments etc.
I believe that the preload screw was moving from shooting etc.
I know from previous testing that the fps was over 1100 fps, for a 14 gr OEM CM pellets. ::)
So, I'll find out ASAP, as soon as LL is back in shooting form today, and set to her good shooting spec's,
again at around 850-860 fps etc.
Your thoughts or suggestions......
Tia,
Don
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Their comments are correct, you need a thinner skirt if you have less pressure, in order for it to expand.... There are other factors to consider than just the width of the skirt at the back edge, however.... If you have two pellets with the same skirt thickness, but one has a deeper cavity, at the same pressure the deeper/longer skirt may expand more.... For instance, a pellet with a dished base, with a 0.010" edge, may not expand at all, while a deep based design might expand with a 0.020" edge.... Also, the larger the caliber, the thicker the edge can be.... The designs I sent to NOE have the skirt thickness scaled to the caliber.... so the larger calibers have thicker skirts.... If you think of the skirt as a tube, the "thickness/diameter" ratio is a constant, because they would both have the same strength (yield point) at the same pressure when designed that way.... I tried to choose a skirt thin enough to expand, but thick enough to be able to fill out when casting.... It seems to be about right, IMO.... I seriously doubt you could blow the skirt up as it exits the muzzle at any of the air pressures we run using pellets....
Bob
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Guys
Here is some interesting info for the swaging of AG pellets.
Food for thought.............. on pellet skirt thickness/psi,
http://www.corbins.com/pellets.htm (http://www.corbins.com/pellets.htm)
I do believe that casting would be better on the funds, than swaging..........IMHO
Thoughts or suggestions.............
Tia,
Don
My Thought, OUCH!!! :o