Gatekeeper25 wrote: ↑Thu Dec 19, 2019 2:21 pm
billsshed wrote:Thanks for the question, I have a little 17Hornet which does 17 and 20 gen projectile very well but as the boiler is small the 30gn is just a little slower. I want the speed.
Ref velocity, the 20gn has now been pushed past 4300f/s and I was interested enough to do the maths and worked out that the surface speed of the jacket for both a 22 cal and a 17 cal. It turns out that the rotational forces on the 17 jacket are far less than the 22cal (as expected). There are other factors that destroy projectiles like barrel roughness, jacket hardness, ( engraveability) and of course jacket thickness. My jackets are only .008” thick (and made from recycled brass )but still behave poorly under 1400f/s no mater the design. I gave up experimenting and just ran the 20gn at 3600and the 17gn a bit faster. Depending on the range the 17gn rarely exits but if the range is only 50m it is just messy.
Bill
Hi Bill, interesting information, thanks. I'm actually considering a 17 Hornet at the moment. Thinking of getting rid of the HMR and moving up a level. Not in a hurry but will do it when the right one comes along.
Do you make projectiles to achieve something that you can't get commercially, or just because you like tinkering?
It's something that I would definitely be interested in attempting but I couldn't justify the set-up cost for the small quantities I would use. How difficult is it to achieve good consistency with the weights? When you are only working with 17gr there is not much of a margin of error.
Ashley
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I make projectiles only for the Calibers I own. I am a tinkerer. I like to see what would happen if....
A jacket weighs 6gn and if you fire it without a core...it does not fly well at all. If your projectile is to long it will tumble but there is a fine line between tumbling and excellent accuracy.
You can build a 17 cal jacket over 2” long which is absolutely useless.
You can buy a truck load of really good projectiles for the set up cost.
My list of mistakes is endless but I have learned a heap.
You can make some excellent projectiles but it takes a lot of time and I have made a lot of the jacket trimming gear my self and have sunk 100s of hours into trying to speed up and make the process as consistent as possible.
Tripod has helped me with casting lead, extruding lead wire and supplying the know how and equipment to do it. That alone is some serious hydraulics and dies to match.
Getting the weight within .2 of a grain is not hard but you must be consistent. To get within .1gn is quite achievable but just be anal. Lube qty when making jackets, lube on cores, cleaning methods of jackets, cleaning of cores, length of jacket, jacket thickness, temp of kiln, time of jackets in kiln etc are all variables. If you are not into making your own gear and loosing whole days behind a press just buy the projectiles that work for you. It will be cheaper / simpler but no fun. High quality scales to weigh the components is another cost.
I got my gear when the Aust $ was above parity to the US$ and it was not so bad. I would hate to pay for it now. Nothing more satisfying than going out at night and knocking them over with projectiles that I made myself.
Sorry for the ramble and I hope I have not discouraged you but you need to go into the process with your eyes open.
Bill
