Sythetic Flashpup Adventure Started

[Rallyshark]

I say go with whichever one you think you'll like the best.  None of the differences between the models affect performance in any way, and they're all capable of the same results  

[QueeQueg]

Hi, I have a .22 FP that I'm going to tune and this thread has some of the best info I've seen yet. For now I'd like to get this thing shooting in the 40ish + range using JSB Ultra Mags for hopefully a full 12 shot mag and seeing what you guys have accomplished makes me confident it should be no problem to achieve this.

Where are you guys sourcing the PEEK 3/8" rod if I may ask?

Thanks

[Rallyshark]

I order mine from Amazon. Just search peek rod, and you'll find it.  You should be able to hit that power level pretty easily.  You could probably do that just by opening up the derlin valve seat a little 

[QueeQueg]

I will try that first with reaming the the delrin seat. I've got a chrono ordered and hopefully next week I can start.

Been watching all the new stuff that's available and the nice stuff already here. Most at serious cost. I've been shooting this Pup for almost a year now and it's already really impressed me. Seeing the potential you can unlock say's maybe I don't need to spend 2k for something I want toss in the truck and go with.

Love your HS adjuster mod.

Thanks for the response and documenting all your research here for us to use.

[Thane]

I have been doing some off hand shooting the Synthetic FlashPup .25 at 57 FPE.

With the stock, short barrel, and typical bullpup center balance at grip she generates a lot of up-flip bringing on severe hold sensitivity.

[Rallyshark]

I have been doing some off hand shooting the Synthetic FlashPup .25 at 57 FPE.

With the stock, short barrel, and typical bullpup center balance at grip she generates a lot of up-flip bringing on severe hold sensitivity.

Sounds like an excuse for a longer barrel to me    Anything you can do to make the part where the barrel goes through the front scope rail mount more rigid will help with that.  I also added a small insert between the barrel and the air cylinder to minimize any further movement too. 

I will try that first with reaming the the delrin seat. I've got a chrono ordered and hopefully next week I can start.

Been watching all the new stuff that's available and the nice stuff already here. Most at serious cost. I've been shooting this Pup for almost a year now and it's already really impressed me. Seeing the potential you can unlock say's maybe I don't need to spend 2k for something I want toss in the truck and go with.

Love your HS adjuster mod.

Thanks for the response and documenting all your research here for us to use.

That's what this stuff is all about, sharing the info   Just do that porting and open up that valve seat, and she'll do that 40 fpe no problem.

[Thane]

Sounds like an excuse for a longer barrel to me    Anything you can do to make the part where the barrel goes through the front scope rail mount more rigid will help with that.  I also added a small insert between the barrel and the air cylinder to minimize any further movement too. 

Yep, been staring long and hard at the rail mounting points. Rear plastic riser with a single bolt and stud is not confidence inspiring.
Working on stiffening it all up, preferably in a straight line and parallel to bore line.

[Rallyshark]

Sounds like an excuse for a longer barrel to me    Anything you can do to make the part where the barrel goes through the front scope rail mount more rigid will help with that.  I also added a small insert between the barrel and the air cylinder to minimize any further movement too. 

Yep, been staring long and hard at the rail mounting points. Rear plastic riser with a single bolt and stud is not confidence inspiring.
Working on stiffening it all up, preferably in a straight line and parallel to bore line.

The single rear bolt doesn't bother me as much as the that front rail mount does.  The mounting at the rear isn't going to be able to move much, since it goes directly to the breech block.  The front mount has a lot more effect on POI, since it can allow more movement.  When I removed the QE, and made an insert to fit the barrel and mount very snug, it really stiffened up the whole gun.  I feel like finding a way to negate any cylinder/barrel movement at the front should absolutely solve any issues.  I haven't decided what my final solution will be, but I'll come up with something sooner or later.  I think a tight fitting barrel band that also fits tight around the muzzle end of the cylinder would probably go a long way.  It is all theory and thinking out loud right now though. 

[Thane]

The racking/twising that is occuring across single fastened points is my current concern.  I can twist the barrel and rail and make POI shifts even with the barrel tightly shimmed using a turned/tapered delrin sleeve. I probably just shouldn't do that.

I agree the breach block is the anchor and I'm wanting to take advantage of the picatinny to lock out not only vertical but lateral motion using a cantilevered/long riser with longer picatinny clamping force. Picking it up again on a forward point with a longer aluminum barrel band and detach th air tube which adds a number of forces to the shot cycle. 2mm walled carbon tube is already epoxy bonded to factory barrel, very stiff. This would also lend itself to a bottle mod... still thinking it through a longer barrel would aid this since it is so compact.

Looking for a suitable chunk of alum in my garage...

[Rallyshark]

The racking/twising that is occuring across single fastened points is my current concern.  I can twist the barrel and rail and make POI shifts even with the barrel tightly shimmed using a turned/tapered delrin sleeve. I probably just shouldn't do that.

I agree the breach block is the anchor and I'm wanting to take advantage of the picatinny to lock out not only vertical but lateral motion using a cantilevered/long riser with longer picatinny clamping force. Picking it up again on a forward point with a longer aluminum barrel band and detach th air tube which adds a number of forces to the shot cycle. 2mm walled carbon tube is already epoxy bonded to factory barrel, very stiff. This would also lend itself to a bottle mod... still thinking it through a longer barrel would aid this since it is so compact.

Looking for a suitable chunk of alum in my garage...

It would seem you're seeing the same stuff I'm seeing.  I've got the up/down movement covered quite well, but I do feel there's some room for stiffening up the lateral movement.  Of course, the elephant in the room that we are ignoring is that Hatsan really was smarter than we may have first considered.  Using the QE shroud to tension the barrel solves many of the issues we are seeing with it removed.  This isn't as much of an issue with the standard Flash, since it uses a more substantial barrel band from the BT65, but the Bullpup variations use a far more flexible band/front rail support.  My SFP is currently wearing a shorter stiffer barrel, and isn't as bad as the 24" barrel I'm fighting on the Turkenstein Flash I got going in the other thread.  I'm considering adding more barrel set screws on the side of the breech like I did on my standard Flash as well.  That certainly did help with the lateral movement, since all the set screws are on the vertical plane from the factory. 

I look forward to seeing what you come up with Thane!  I did get around to adding a PEEK probe support on the Turkenstein like you did with the black derlin though   See reply #22
https://www.gatewaytoairguns.org/GTA/index.php?topic=166895.msg155872427#msg155872427

[Thane]

I like what Donny did on the Turkinstein to stiffen up the barrel band and reduce racking with a carbon fiber reinforcement (I have to try that as well).

This is a different approach using the breach block milled rail to assist in holding the scope rail straight/aligned parallel with breach block and barrel,  ultimately reduced twisting. I used one piccatiny adapter/riser on the breach block and another long cantilever rail riser to the forward barrel band. Shaved down the barrel band top to make rail parallel to bore. Also filed side notches to make a tight, mated fit into the channel under the new rail, resisting rotation and side to side motion. Finally cut excess rail to length.

Before the rail could be flexed and twisted by hand, much stiffer now, no twisting since the rail purchase is multiple times the original bolt and stud.

[Rallyshark]

That's a great idea Thane!  I didn't even think about doing that, but it makes perfect sense!  It was probably less trouble than what I did too.  Let us know how it does, once you get it on a target.  I think that flexing is for sure the biggest issue with the pups being accurate, especially without the QE.  I may try and do something similar on the SFP too.  I want to wait and see how things turn out with the Turkenstein first though.  I'm also toying with making a band that locks onto the end of the cylinder/barrel too, but I don't know if I'll need to or not yet.  More testing is needed...

[Thane]

I started sizing up some aluminum for a new/ longer forward band machine job, but decided to save it for a bottling project...

Last night I gave a hard CCW twist across rail and barrel, punch a few holes at 10 yds, followed by a CW twist (no movement or flex, very rigid) and its all same hole.

Need to push it to 30yds before I call it good, it's already better.

[Rallyshark]

I started sizing up some aluminum for a new/ longer forward band machine job, but decided to save it for a bottling project...

Last night I gave a hard CCW twist across rail and barrel, punch a few holes at 10 yds, followed by a CW twist (no movement or flex, very rigid) and its all same hole.

Need to push it to 30yds before I call it good, it's already better.

Yep, you'll definitely know more, once you stretch the distance out.  Hopefully it will be spot on.  Where did you get that long rail from?  I've seen those little adapters at a few places.  I may want to give that a try with my SFP or the Turkenstein down the road.  Can you post a full gun picture with that new rail installed?  I'm curious to how it looks now.

[Thane]

I used this 34 slot with long clamp, but cut it down to 25 slots:



These adapters:



I'm sure there are many others that would work, main thing is getting as much purchase as possible on the breach block.

[Rallyshark]

That doesn't look bad at all, looks like it is factory!  I just ordered those parts to play with, thanks for the links!

[Rallyshark]

Hey Thane, I just remembered something...  Now that you aren't using that screw in the breech that was holding the factory rail at the rear, you have an additional barrel set screw you can add    I did that on my regular Flash a while back.  That extra set screw would certainly add to the cause, should you decide to tension the barrel using some 20mm OD carbon and the LDC to tighten it down.  You wouldn't need that little insert there in the front rail support/barrel band. 

I ordered a UTG dovetail to weaver mount that sits a bit higher, so I shouldn't have to take off much if any on that front support.  I'll chop off part of the UTG adapter, of course.  This should be way less trouble than carbon piece added to the front support!  I will be testing this on my SFP for sure.  Of course, I'm still waiting for a chance to put the Turkenstein through it's paces too, but I can't seem to get off work in time lately  

[fgwhite]

i took the rail from my flash pup sen and bolted it right down on my bully this rail 3911 hatsan part number they said not in stock to buy its same rail on flash pup and the bull master i used it on the bully figured it was not hollow in under it like the bully one was then i cut the bully rail same length as pup and put it on pup now i see thane set up is 10 times better looks like he even shimed the carbon tube up to make it stiffer i can see now under the rail on recever this spacer is i think plastic and only 1 bolt throught it i can see that being a weak point

[DLP]

I drilled the valve, barrel and transfer port on my .25 Flashpup. Finished tuning it today. I am getting 53 fpe for 20 shots using the Hades 26.54 grain. I pulled the stock QE shroud off and added a CF 20 mm x 18mm tube over the barrel. I used the stock shroud bushing from the breach block end at the muzzle and an Oring in its place. The CF tube fits like a glove. I will order another bushing from Hatsan to replace the rear Oring. I also added a DonnFL Ronin suppressor to the end. This also helped tightened up the barrel flex.

[Rallyshark]

i took the rail from my flash pup sen and bolted it right down on my bully this rail 3911 hatsan part number they said not in stock to buy its same rail on flash pup and the bull master i used it on the bully figured it was not hollow in under it like the bully one was then i cut the bully rail same length as pup and put it on pup now i see thane set up is 10 times better looks like he even shimed the carbon tube up to make it stiffer i can see now under the rail on recever this spacer is i think plastic and only 1 bolt throught it i can see that being a weak point

Yep, Thane's setup seems like a good solution for sure.  I did a separate post about making a sleeve to fit around the barrel/carbon tube to make the barrel fit tight through that front rail support a while back.  That sleeve/shim is critical, if the QE is removed.  The QE tensioning the barrel is a large part of what keeps the barrel stable from the factory. 

I drilled the valve, barrel and transfer port on my .25 Flashpup. Finished tuning it today. I am getting 53 fpe for 20 shots using the Hades 26.54 grain. I pulled the stock QE shroud off and added a CF 20 mm x 18mm tube over the barrel. I used the stock shroud bushing from the breach block end at the muzzle and an Oring in its place. The CF tube fits like a glove. I will order another bushing from Hatsan to replace the rear Oring. I also added a DonnFL Ronin suppressor to the end. This also helped tightened up the barrel flex.

There ain't nothing at all wrong with that tune   That sounds like a perfect hunting tune to me.  I think the 20mm carbon tube is a good move.  I've thought about doing that for a while, but didn't want to order a 1000mm long piece on the slow boat from China, since there wasn't any available for prime shipping at the time I looked.  The 500 mm piece wouldn't have been long enough with the longer barrels I was playing with.  It is good to know that the factory bushing fits inside the 18mm ID carbon tube too!  I think I have about 4 of the QE shrouds and bushings floating around here at the moment,lol.  I've since went back to a shorter barrel on my SFP, so I guess it is time to order some more carbon tube to play with  

Between all of us and our own ideas about stiffening things up, I'd say there are plenty of solutions to solve removing that QE from the Flashpups!