Air Gun Home :: View topic

Alucard · Member

Well, I figured this would be the best place to make this thread. As some of you know, I am looking at building a Pneumatic Air rifle. I need to ask a few questions about what you all would like most.

1. Semi Auto, Single shot Magazine, Bolt action load a bullet each time?
2. What caliber? Would you all like to see one that can change barrel's for each caliber?
3. Would you like a Tank in the stock system (Think Airforce Talon/Condor or L96 with scuba tank in stock(Remove but pad then plug in Pump or Compressor and charge)) or a QEV style system with a long tank under the barrel?
4. What would you be willing to pay for such a rifle?
5. How big is too big?( This means power level's, gun size, and ammunition size)
6. Would a integrated suppressor make it more appealing? Perhaps a baffling system like on the marauder.

The sooner you get back to me the sooner we can start :D

Alucard · Member

I did a bit of research and drew a few base diagrams and here is what where looking at.

rsterne · Moderator

If you're serious, I would recommend you work on a regulated PCP.... Get away from the "curved shot string, maybe it will be OK if I use the right pellet / hammer spring from pressure A to pressure B" idea.... Make an internal regulator, set for a realistic pressure (1500 psi would allow you to shoot 1/2 a tank from 3000) and an adjustable hammer so that the shooter can pick the velocity / number of shots combination that he wants and have every shot at the same velocity....

Unless you are after the FT market (and if you are, the gun better be perfect), I would forget .177.... concentrate on .22 cal because of the availability of pellets in weights up to 32.4 grains.... but if you make a .25 cal version available I'm sure there are those that would be interested.... just don't make that the only version....

I think that the move to multi-shot magazines is here, so you should at least have that as an option (8-10 shot) if not standard.... If it has a magazine, then you should have a single shot drop-in platform so that it can be shot that way.... bolt action or side lever would probably be most peoples choice....

I personally like light guns.... 7 lbs. without a scope is the MAXIMUM, and I prefer the gun to be under 7 lbs WITH scope for packing around all day hunting.... You can never have too much power in some peoples opinion, and realistically, 30 FPE in .22 cal is a pretty good punch, but I would recommend about 40 FPE.... It's imperative to keep the velocity in the high sub-sonic range (~ 900 - 1000 fps) to get a balance between flat trajectory and accuracy.... and it's a good idea to consider what pellets have good ballistics at those velocities....

At 40 FPE, you get the following velocities (these pellets have excellent ballistics coefficients):

JSB Heavy 18.0 gr. = 1000 fps
Beeman Kodiak / H&N Baracuda 21.1 gr. = 923 fps
H&N Rabbit Magnum II 24.7 gr. = 853 fps

Then you get into the longer pellets that would be harder to put in a magazine, and may actually have poorer ballistics coefficents than the above:

Predator Big Boy 26.0 gr. = 832 fps
Eun Jin Domed 28.0 gr. = 801 fps
Eun Jin Pointed 32.4 gr. = 745 fps

Now remember that heavier pellets usually perform better (ie develop more energy) in PCPs, and I would bet that if you set the gun up for 1000 fps with an 18 gr. pellet it would probably be more like 46 FPE with 32.4 gr. (ie 800 fps).... In addition, it would drive 14.3 gr pellets nearly if not supersonic, certainly Hobbies (11.9 gr) would make a nice crack.... and there are those that get a kick out of that (and there aren't many .22s that have that ability).... I don't think anyone but a power junkie would complain about that power range.... and if you start trying for 60 FPE you are competing directly with a Condor at a pretty tough price point for the power....

Once again, these numbers are at the top end of the range.... I think it is equally important to be able to dial the power down to the 500 fps range with 14.3 gr pellets for plinking.... with tons of shots per fill.... A supressor is a tough call.... Many countries (and states) don't allow them.... so you might be hurting the mass appeal.... I couldn't buy one!....

I personally think the tank in the stock (Condor) is ugly, but it is simple.... I also don't like the high scope mounts required with that design.... I prefer the classic lines of a gun with a tube under the barrel and a wooden stock, but that's just me.... In addition, if you copy a Condor, even if it's regulated, the competition is pretty tough....

To be realistic, if you could build an 8 shot Discovery/Marauder with an internal regulator, a ~1" tube (instead of 7/8"), that could be pumped to 3000 psi and shot down to a regulated 1500 psi that would deliver about 40 FPE with 18 gr. pellets you'd have a heck of a marketable gun.... If properly done, it would beat the socks off a Marauder.... and I see no reason it can't be done for the same price ($500).... In limited quantities, maybe not.... but it won't be long until you can buy a gun with exactly the features I am describing.... likely at that price point....

Bob

dummyracer36 · Senior Member

alucard, fisrt, let me welcome you to the forum.

i think bob outlined most of the major considerations.

but i do have to ask, what exactly are your capabilities? machinist, engineer.. ect?

Alucard · Member

rsterne · Moderator

Alucard · Member

broommaster2000 · Moderator

No gun is to big. Only to small. That came out wrong didn't it? Mr. Green

rsterne · Moderator

Ahhhhhhh.... I get it.... Of course if you look at the length of my post (apparently a total waste of my time as you have already made up your mind without waiting for input) and the times of the posts, you will realize I was writing that (hell, only took me an hour or so) at the same time you posted your response to your own questions.... so it would have been impossible for me to read it.... Shocked

Good luck with your project.... I'm not interested in a .338.... Rolling Eyes

Bob

Alucard · Member

broommaster2000 · Moderator

That might work if you have a breech, scope and barrel attached to each other. You will always have to adjust your scope anyway. Neutral

We have discussed this here:

http://www.airgunhome.com/agforum/viewtopic.php?t=3692

Alucard · Member

Update: Here is where im at so far, Essentially their is an inner bull barrel connected to a bolt, it is in its normal state when pulled back completely and the bolt is locked down, this has the barrel sealed to the piston. When you undo the bolt and push forwards, the inner bull barrel is pushed out of the thin outer shroud into the mock suppressor(sheer cosmetic's people) allowing you to place in your projectile. Then you pull the bolt back and lock it down sealing your projectile to the piston, when you pull the trigger on the blow gun(modified by me too have a decent trigger pull as well as being almost only a trigger) The air comes from under the barrel,(Providing you release the ball valve first) Around the L joint, the piston would already be back, and the air would simply push out the barrel, then the piston would return back to normal position, you would repeat until out of air, I will be housing the entire thing inside of a L96 style stock, I have a custom built in bipod system designed, however due to the option of releasing all the air at once(Extreme power and recoil) I think I must build the scope into the rifle (So you cant remove it etc.) Now I think im going to start simple, and use cheap hardware store fittings at low psi (100-300) To be sure my design will work, then I will start to machine the parts for high pressure use. This will be one bad a$$ rifle. I would share more details, but I cant as of now as I dont wish my invention to be ripped off.

jlwilliams · Veteran Member

My opinion is that it would be best to have the barrel readily changeable. That would allow for caliber changes as well as making moderated or unmoderated barrel an easy swap. As much as I like a moderated barrel, I think that you would eliminate potential customers in places where they are not allowed.

dogon1013 · Member

Alucard,

have you found what the rifling imprintation force is for the .338 rifle bullets?

I played around with some copper jacketed .22 bullets for airguns and the imprintation force was too high to work at airgun pressures. The copper jackets are just too hard and there is too much material to move to be a viable option. Softer lead "bullets" could work.

fritz · Silver Status Member

What about a .30?

Molybdenum lubed bullets?