Sythetic Flashpup Adventure Started

[Thane]

That is a great string for unregulated gun. If I can pull a string under 3.5-4.0 ES without a regulator it is a done deal, no creep guaranteed.

[Rallyshark]

That is a great string for unregulated gun. If I can pull a string under 3.5-4.0 ES without a regulator it is a done deal, no creep guaranteed.

I completely agree. If you can get the string you want without a reg, then it usually works better in the long run. I use this gun for long range stuff, which is why I wanted to give it a try, but a reg just wasn't the best move with the current setup. 

I may revisit the reg idea, when I see what Duy comes up with on his bottle configuration though! A bottle with that much plenum should be able to handle most any power level.

[mackeral5]

I played with Bobs lofty formula. which is as below for .25 cal.

port X caliber X pi/4 X psi=fpe

.217x.250x3.14159/4x3000psi=127fpe

then take that and calculate with the barrel length. divided by the foot

127x17.7/12/2=94fpe.

and throw in some 20% loss.

94-18.8=75fpe.

I am thinking it will be close to 75fpe with .218 exhaust port and bridging 80fpe with .250 port. we will see.

I am not too worried about the screws. ill find a workaround.

If you have a mininlathe you can do it. I am thinking a stainless steel seat and peek poppet with 2mm stem or less. should even be easier to do vs making a metal poppet and peek seat. 

i am sure you can tune it for efficiency, given if you have a big plenum. thats why i am going with 125cc from the tube. i can swap for 22/25/30 caliber later on. if the HS cant open it. balance it will be. there is enough room...

I look forward to seeing how this one does, for some reason there seems to be a much bigger difference than "just 1.5 inches" when going down from 18.5 to 17", for example.  for mid power and lower tunes, not a big deal.  But when pushing high power tunes for the caliber a 17" barrel becomes a big constraint.  Air consumption gets a little gnarly when swinging for the fences with short barrels. 

[darkcharisma]

I measured the plenum with fluid. its actually 140cc not counting the valve area. i only cut 3/4 past the threaded area and have 9.5" tube length.

the valve exhaust indeed doesnt line up with the breech ports like you mentioned... and the max barrel port i can do without hitting the oring grooves is .217...for the oem barrel anyway. the ID behind the throat is .220, i can fit a .217 reamer loosely in there. sooo...restrictive.

Ahhh.. creeping regulators...
====

yah Mike, need to find out how close i can get to that fomula.

[Rallyshark]

I measured the plenum with fluid. its actually 140cc not counting the valve area. i only cut 3/4 past the threaded area and have 9.5" tube length.

the valve exhaust indeed doesnt line up with the breech ports like you mentioned... and the max barrel port i can do without hitting the oring grooves is .217...for the oem barrel anyway. the ID behind the throat is .220, i can fit a .217 reamer loosely in there. sooo...restrictive.

Ahhh.. creeping regulators...
====

yah Mike, need to find out how close i can get to that fomula.

That misaligned valve exit makes me wonder what I left on the table with my .177 slug gun...  I knew the hole was a bit too far towards the muzzle, but just assumed it was on center otherwise.  Fortunately, it still has the juice to send the 21 grain NSA .177 slugs darn near supersonic, and it doesn't like any of the heavier slugs out there.  I just happened to notice it when I was doing this WFP valve for my .22.  Now that I'm thinking about it, I'm temped to go see what the top end of power is.  I may do it at some point.

With that kind of plenum available, you won't have to worry about it limiting your power I don't think.  It should be capable of some pretty crazy numbers if you go with .217 porting and the larger valve poppet/seat arrangement!  Hurry up and finish that thing Duy,lol!

[darkcharisma]

got the block done. just need to mod the valve, do the ports and machine a pic rail for bipod mount. the bottle sticks out so definitely get an ldc, cut the tube a bit shorter, get a longer barrel, or smaller tank,  lots of options. cut the stock 1/4 inch too short.

[Rallyshark]

Nice job on the block!  I wish I had the tools/skills to make a block.  If you made a liner barrel, it would save you a little weight and get some more barrel length.  A 600mm would be a solid length(without being too long), and get you that power you're after for sure. 

Don't feel bad about cutting the stock a little short.  I opened up the front side of the stock thinking I would need to open it all the way up for the longer cylinder, but I didn't consider the fact that the cylinder doesn't sit all the way down in the stock.  In other words, I wasted a lot of effort opening it up more than was necessary.  I'm considering "bedding" the cylinder forward of the front rail mount.  It is pretty darn solid without doing that though. 

[darkcharisma]

I think the mini lathe should be able to hold a block with it's 3 chucks. I have a bigger lathe and just used the 3 chucks to hold it in and machine away. it's not that complicated, drill, bore, tap then flip and repeat.

Looks like I can't test the before and after boring the ID of the valve. I tapped a peek seat in too hard and nicked the surface, hard to get out so i drilled and bore it out. ehhh. its in the plans. hopefully get it done today and tune later.

[mackeral5]

I like the tank block.

[Thane]

Looks great!

Forward weight will definitely help balance at higher powers.

[mrbulk]

got the block done. just need to mod the valve, do the ports and machine a pic rail for bipod mount. the bottle sticks out so definitely get an ldc, cut the tube a bit shorter, get a longer barrel, or smaller tank,  lots of options. cut the stock 1/4 inch too short.

Duy, a quick question if you don't mind? I have a similar block (aluminum, made for CO2 by a late buddy from long ago), do you think it would accept a HPA bottle with in-line regulator set to CO2 pressure (~1000psi)? Then I could shoot it through my bulkfilled CO2 QB78 for which the block was originally set up.

[Rallyshark]

I think the mini lathe should be able to hold a block with it's 3 chucks. I have a bigger lathe and just used the 3 chucks to hold it in and machine away. it's not that complicated, drill, bore, tap then flip and repeat.

Looks like I can't test the before and after boring the ID of the valve. I tapped a peek seat in too hard and nicked the surface, hard to get out so i drilled and bore it out. ehhh. its in the plans. hopefully get it done today and tune later.

I don't know if I'd have the clearance to spin the block, and I don't have the tooling for sure.  I'd have to cut the threads, and the mini lathe isn't exactly the most rigid piece of equipment,lol.  Also, the bed isn't long enough for me to chuck up the tube and cut threads on it either.  Maybe, I'll upgrade the lathe and tooling some day.  Until then, I'll have to live vicariously though others' magic  

Please post pictures of the valve seat/poppet when you get done too.  I'm really curious to see how that turns out!

[Rallyshark]

Okay, here's a couple of pictures of the finished product.  I put a Yankee Hill 6" rail extension it to move the bipod farther out, and to avoid resting the cylinder on a bag.  I really like that extension, because it is sleek and low profile.  It is a very solid piece, but they ain't exactly cheap.  Also added a BT65 barrel band at the front of the cylinder.  It has two smooth faced allen screws in it to firmly secure the setup(that's what the little hole in it is), and I removed the nut section from the bottom of it.  Needless to say, that barrel setup is RIGID.  I can pick the gun up by the barrel, and it doesn't move!  Weight gain was very minimal, since the BT cylinder is aluminum, and the factory one is steel. 

I'm pretty happy with the finished product, even if the reg was a bust on it.  She's a hammer, and her only job is slugs

[darkcharisma]

looks good Donny, it certainly is faster doing that compared to mine. but i am almost ready.

i cant mod the probe because the bolt to unscrew the handle is screwed up. havent mod the hammer spring tension yet. ill slap together and do some initial strings then mod those later.

is your minilathe 7-14? you should try it. stick a 2.5"x1.25"x1.25" block and see. i dont thread tubes if i can get away with it, takes a whole day to set up and cut threads. so i used 4 screws to plug the block end.
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Mrbulk, if your friend made it for co2. as long as you stay under 1200psi, you should be good. make sure you take some measurements of thicknesses and rxactly what type of material being used. you can calculate it. 6061 is less strong than 7075 that i am using.

[Rallyshark]

That valve should flow quite a bit better!  I like the way you did that.  What opening is the seat now?  I can't wait to see how it works out.

I hear ya on the threading.  Mine is a 7 x10 mini lathe, and changing out the gears just to change threads is not any fun   Mine pretty much stays on 1/2-20, haha.  I usually do the turning manually, rather than using the auto feed(unless threading a barrel).  I feel like I have more control on the feed that way. 

[darkcharisma]

seat is .225. poppet .257. ports are .2175.

max hammer 33.95=984fps at 3000psi. Not bad for a 17.7" barrel. i guess i can either tune to keep a 60fpe short barrel or ho with a longer barrel and max it out later. i happen to have a bullboss barrel...

[mackeral5]

seat is .225. poppet .257. ports are .2175.

max hammer 33.95=984fps at 3000psi. Not bad for a 17.7" barrel. i guess i can either tune to keep a 60fpe short barrel or ho with a longer barrel and max it out later. i happen to have a bullboss barrel...

Good job..not going to get much more than that out of less than 18" of barrrel....

[Rallyshark]

That's really good for the factory barrel!  A longer barrel will certainly bring it up a few notches.  I can't remember which, but I think the Bullboss barrel is smaller in diameter on the section that goes into the breech.  If that is the case, it won't gain you a whole lot, since you'll have to chop it.  If weight isn't a concern, you could order a 24" blank and have at it.  I've had really good luck making barrels with the FX slug liners.  I made one with the 500, 600, and 700mm.  The 700mm is what lives on the gun though.  All of the slug liners I've made shoot pellets very well too.  There's also the Brownells liners you could play with without too much cost. 

You have so many options for this gun.  The sky is the limit for ya

[darkcharisma]

I can get more fpe but its not worth the trouble. i would have to open up the ports to bore size. like you said, maybe 75 fpe max with the 17.7" barrel. ill provably detune for 60fpe and be a woods gun.

this number is a few fpe off from Bobs lofty calculation. i got 73fpe instead of 75 previously stated. so from there we can calculate the fpe proportion to a barrel length.

so .217x.250x3.13159/4x3000=127(fpe)x24/12/2=127x.22%=99fpe. or somewhere around 90-95fpe based on the .217 port.

I have a .172/257/308 and alot of 22/25 cal fx liners and those brownell liners too. i have to see which one gets left behind if not going into an impact or crown.

[darkcharisma]

Interesting..the previous testing was done unregulated.
This time i lower the reg down to 150 bars. i got 899fps with 34 grains. That big plenum really does wonders.