.257 QUESTIONS!
Good day all- I have a few questions about a .257 build… What would be a good barrel length to use? I’d like to keep the rifle handy, and it’s going to be shrouded… Im thinking anywhere between 24″-28″ would be okay. I’m of course going with a TJ liner, but which one do I get? the 1:14″ or the 1:10″ twist? Would 1000 cc’s be alright? I’m going to have two 500 cc tanks linked together. They’re both 3k psi though… would this be a alright set up? I know most of you guys building on a AF rifle are using the larger 4.5k tanks, so I wasn’t sure. Thoughts??
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Yeah Cedric, I tried the 100 gr spitzers but I did not chrony them first. They didn’t shoot as well as the lighter lymans as I expected without cranking up the power wheel. When I get to finally do some “longer range” shooting I will first see how much more pre-load I need for the spitzers to discover if my barrel even likes them???
Hell, “Sumo .257” is okay but I think it may end up being a “Sumonster .257! 😈
Thanks Ced!! That’s what I was after! Oh man… If only I could get this body idea done, we’ll be set!! :8:
caboose,
you will get a bout a 1/3 to 1/2 MORE with the 4500 psi vs the 3000 psi
Even though they both are 68 CI, the one filled to 4500 psi HAS MORE AIR IN IT.
True… but I wonder how to calculate the difference in the amount of air is in a 68/3000 vs. a 68/4500… well, over a 1000 cc’s is still better than 490 cc’s any way you look at it! I should be able to tune for a good power curve with this much air… I’m not looking for a ridiculous amount of shots- I just wanted a better curve, for better consistency. Now I just have to figure out how to make this body so I can put together the rest of this rifle and get to shooting!!! I want to join the 12oz Long Range club!!!!!!! Then maybe see how we all do shooting groups at range. Though with some the set ups, like Roach, yours (Ced), and 80 Grit’s… I’m not sure if it would be fair- it’s like comparing apples to oranges! Still waaay cool though!
Well, you WILL have more air. The OEM Air force bottles are 29ci or 490cc and rated at 3000 psi. So your 68 ci at 4500 psi WILL give you more fills and more shots.
only 1600 cc? HTF did I mess that up?! Hmmm… would the tank being a 68 cu in 4500 psi instead of 3000 psi not up the amount of available air? otherwise, what’s the point of having 3k vs 4.5k? just wondering.
Caboose,
Sorry bro, been at work all day. I know nothing about regulators. But hell, 3000 output sounds good to me…..lol!
68 CI equals to 1114.32035 cc’s on top of your standard 490 cc tank, you would only have 1604 cc’s
I just looked up his regs- he’s got 4500 psi input, and 1000-3000 psi output. Of course, I could also use a 68/3000 but I know there’s more air in the 4500 psi tank. His 3000 psi input regs can do 700-3000 psi output. I’m just not sure which to use… Ive emailed him, waiting on a reply
I want to get away from gun mounted tanks though- well, at least a secondary tank not mounted to the gun- I’m okay with wearing a 68/4500 tank on my back, or in a butt pack or something… and with the combined 490cc and the 68/4500 I’m looking at over 2,604 cc of air… Roach- what would be a good output pressure for that 68/4500? JDS Airman regs will fit in a standard paintball tank (the 68/4500), I just need to know what output pressure to use… I’m not even sure- 3,000? Less? I have no clue!!
My idea for the set up on a AF frame is influenced by the terrible ergonomics made worse by a larger tank.
So do short etac between the bottle and Dougs valve for a prechamer, a Tony dog leg adapter, gauge replaced by a nipple anda elbow fitting and line where the gauge was, running to another AF tank under the barrel where the forearm is with a Etac what has a gauge, fill nipple, and where the valve would normally screw in another nipple for the line to attach to, all feeding one of Doug’s valves.
The Forearm tank is secured to the rail by scope bases with the rings milled off and a slot cut in each for a screw pipe clap that passes thru the scope mount and around the bottle and is tightened to secure it. Secured by the clap bands on the bottom of the tank is a rail to attach a AR foregrip/bipod. Then you have 1000 CC.
RC
Damn- Ced, I wish you could see those pics! I posted them on the .257 Reference Guide post as well… I could email them to you. Anyhoo, I get what you’re saying about the barrel doing the work, so I’ll probably be using a 28″ barrel. I’m going to shroud it though, and with the barrel length plus the shroud- that’s going to be really long. 🙁 My thought with the remote set up is that I would effectively have over 2,640 cc’s of air, having the 68 cu in tank feed the 490 cc tank. Please correct me if I’m wrong, I’m not actually sure how the 68 cu in 4500 psi tank would work out to be in cc’s. I just did a straight conversion from cubic inches to cc’s. And would setting the gun up for remote be as simple as figuring out a good output pressure for the 68/4500 tank into the AF tank, and hook it together? That’s how it works with paintball anyway. But this isn’t paintball, and I’d like to be sure! Which brings me to another question, what would be a good output pressure for the 68/4500? If anyone is confused by hooking the gun up via remote, another name for it would be tethering. Tethering with a small tank I can wear on my back… 😀 Paintball is a perfect example:
except in my case, the remote will be connected to Tony’s tank adapter, and the other end will be connected to the 68/4500 tank. Thoughts?? This is going to be a bitchin gun!! 😈
caboose,
Can’t see any of the pics you posted…..ARGGGGH! Why cant computers be more user/viewer friendly?
also, a lot of things can be done and your volume of air depends on how much you push the caliber. The faster obviously the more air you use. So yeah, at 900-950 fps, 800cc’s could give you OVER 10 shots but I would opt for a 28″ tube over the 24″. That way, you let the barrel make your speed as opposed to the VALVE/AIR making speed. My OEM Airforce tank (490cc) pushing 257420 bullets at only 900 fps BARELY gave me 5 clean shots before I had to refill. My TD257 tank is 53 ci which is 869 cc(868.5cc) and I get 10 good EVEN shots but can go over 20 if i’m just goofing off after the first 10…lol! And my gun is using a 26 5/8″ barrel and shooting the lymans at 1005 fps. Shooting the 100 grainers, that shot count goes down to about 6-7 before accuracy tapers off. But also, I crank up my powerwheel from 2-8 to 3-1 when I switch bullet weights.
So its just easier for me to stick with 60-83 gr bullets and shoot them all from 2-8 on the power wheel.
A shame we can’t get our hands on a cf bottle the proper size. Somthing on the order of the bottle being used on the Evanix Monster. Hmmm-something to think about. 😉
Knifemaker
What about a reg from JDSairman with a specific output pressure for remote?? I’m not sure how to figure out what that would be- The AF tank acting as a “prechamber” for firing the airgun, and the 68/4500psi tank as the “main tank”… I’m not sure how to word that.
Here’s another thought as well, Eliseo type rifle build…
big main tube, attach the trigger group….
Obviously the bolt handle cut-out would be reverse… POSSIBILITIES!!
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One can hope… He may do another run of those Sumo actions, so I’ll definitely keep an ear out for that… but I’ll build on a AF-like body for now until or even if Chip decides to do another run of Sumo actions.