TVBA-BBS

[)DEMON(]

Great work!, this must be one of the best snipers out there. Not to mention the fact that it really is a true functioning sniper.
Great idea with the gel, I have to try that sometime.
Do you have a nick-name for your cannon because the name is a bit hard to swallow.

[Brian the brain]

Very nice job!!
The silencer will complete the sniper look and feel of this beast!.
Just need a nice paintjob now.
My compliments.
Finally something new!!

[Kris.Is.Awesome]

Is it me- or is your chamber wrapped in FG/CF/Kevlar?


Looks.. like it. But very VERY nice gun!

Hah... Nevermind. I see it's just Duct tape...

[SniperMan]

thanks for the comments ppl, much appreciated!

Hah... Nevermind. I see it's just Duct tape...

Almost - it's race tape stuff. You know the stuff that has string in it as well. Kevlar....now that's an idea!! I have a cousin that does stuff in that..hmm

Anyway's the silencer is almost done!!

pic below of the basic design. Mine is different but the same basic principal. Aluminium pipe, washers and some aluminium rod. Not too hard. The difference being that mine is longer and has 10 sets of washers. I'm using 1.5" outer (1/8" thick) with 1.25" inner bits.

Once done, i'm going to polish it up so it looks the part.

The bit that is going over the barrel itself is 3" long to make sure it's nice and stable. The end plug is 4/5"

The design picture comes from a pdf that i found in 'the usual places' called 'The silencer cookbook'

There are more in depth designs but for something this small and only air powered, i cant see that the better designs would be needed.

[frankrede]

Correct me if I am wrong ,but is it semi-auto?
In the video it seemed that way.

[SniperMan]

Correct me if I am wrong ,but is it semi-auto?
In the video it seemed that way.

No, it can fire semi auto but it has no ammo autoloading mech. It's bolt action. Still better than a standard muzzle loader IMO.

Maybe in the future i will make it a semi but then safety is a bit more of an issue. Plus it means more moving parts to fail...

Status of silencer pic below...
Just have to assemble it now. Shouldn't take long but it'll have to wait till a bit later in the day, other things to do....

[M3NT4L]

One inch in ballistics gel is about a 79 percent fatal hit. The penetration you hit was fkin scary thats a waaaaaaaaaay powerfull "potato gun".

[MrCrowley]

yeah but thats not the true balistics gel, that stuff doesnt have the same properties as human flesh real gel is very close,although this gel isnt bad if you shot a person with that sniper it wouldnt go that deep.

[SniperMan]

One inch in ballistics gel is about a 79 percent fatal hit. The penetration you hit was fkin scary thats a waaaaaaaaaay powerfull "potato gun".

Where did you read that??? Fatal depends on where it hits. Not exactly going to be faltal if it hit you in the arm is it. Ballistics gel purely just gives an indication of penetration into human flesh and does not include bone. Although bone can be cast into it if you want.

True ballistics gel IS JUST GELATINE - the difference is that it's not just home grade for making cakes, it's a commercial grade specifically designed for ballistics use and is therefore made to a specific/controlled recipie/concistency. Who cares if your cake does not quite set...

Unfortunately i don't have a .177 cal bb gun to do the actual calibration but the calibration shot is a .177 cal bb at 500fps getting about 7-8cm penetration from memory.

So, based on my measured velocity of the BB, it should penetrate more than a .177 because of more mass. Maybe it's not quite dense enough but it'd be around the mark.

Either way, there's no way that i'd want to be in front of this thing....the penetration based on the ballistics gel would almost go through my thigh.

[SniperMan]

http://en.wikipedia.org/wiki/Ballistics_gel

Not far off:

To ensure accurate results, immediately prior to use, the gelatin block is "calibrated" by firing into it a standard .177 caliber (4.5 mm) steel BB, from an air gun over a chronograph into the gelatin, and the depth of penetration measured. While the exact calibration methods vary slightly, the calibration method used by the INS National Firearms Unit is fairly typical. It requires a velocity of 600 ± 10 f/s (183 ± 3 m/s), and a BB penetration between 3.25 and 3.75 inches (8.3 to 9.5 cm).

[SniperMan]

Hmm, well i've got mixed emotions on the silencer. It works well to quieten it down but by no means makes it silent (not that i expected it to). It also appears to reduce the power of it by a reasonable amount. i.e. i'm now getting a consistently low shot by about 25cm at 15m so it's reducing the power quite a bit.

It could just be percieved lower power tho - The weight of the silencer may be flexing the barrel - i don't think it is but it's a possibility.

There may be some other options to make it flow a little better but still retain the silencing effect but i'll have to investigate. I may be able to reduce the amount of washers in it but keep the length or just reduce the whole lot. It does seem a little weird that this is supposed to work really well for a .22 but it's not doing so well with the bb.

[Jolly Roger]

Hey just wondering about your design, I still can't figure out how it works... I've attached a simple sketch, anything like it? The red is the piston, blue is the pressurized areas. (The air leaks around the piston as in a normal piston based cannon)... It's got me puzzled...

[Brian the brain]

For the silencer it might be a better idea to drill holes in the barrel( get a longer one to keep the same effective lenght) and put the silencer casing over it.Fill the lot up with soft foam.The kind you'll find in a matress.
This worked for me.
Built out of aluminium it should be very sweet.

[SniperMan]

Hey just wondering about your design, I still can't figure out how it works... I've attached a simple sketch, anything like it? The red is the piston, blue is the pressurized areas. (The air leaks around the piston as in a normal piston based cannon)... It's got me puzzled...

Yes, it's identical to that. No spring however, it's just free moving.

In my original design, i just had exactly that - a 'T' piece went to a schrader valve, the other to an exhaust valve.

The multiple valve setup just simplifies this charge/discharge procedure.

Basically, air is permanently charging the chamber. When i hit the button on the blue valve, it pneumatically activates the solenoid on the other (big) valve. This then switches the 'chamber' air to exhaust through the blue/white/black thing (it's a mini silencer), throwing the piston back (as would normally happen.

This has some real advantages. There is no need to be fast on the trigger, as soon as almost any air hits the solenoid, it activates and does so very rapidly. Also you get the added bonus of not having to constantly recharge or even worry about leaks. It does however make it a little risky when it comes to disconnecting from the air source as it will fire. What i ideally need is a schrader/check valve on the air 'in' so that it will not fire if for example the air line came off or burst.

To explain better, adding to your diagram...

[SniperMan]

For the silencer it might be a better idea to drill holes in the barrel( get a longer one to keep the same effective lenght) and put the silencer casing over it.Fill the lot up with soft foam.The kind you'll find in a matress.
This worked for me.
Built out of aluminium it should be very sweet.

Yeah, i thought about that but decided that i'd rather not make a new barrel and it would get pretty hard because of the fact that it's double skinned. I'll have a bash at a revised design reducing the volume of air between each washer by about 1/2. Hopefully that will give good results by reducing turbulance in the silencer.