Making of a Field Target rifle .... From a JSAR Raptor Mini

[E30_S50]

That's pretty sweet! You guys should offer it as a package option...Raptor Motörhead Edition.

[KnifeMaker]

Oddly, the first bbl. I used, the TJ from JSAR blew the o rings over and over. Never more than a few shots before they would fail.


This is why I put the o ring on the probe. It cured the issue. 

[oldpro]

Oddly, the first bbl. I used, the TJ from JSAR blew the o rings over and over. Never more than a few shots before they would fail.


This is why I put the o ring on the probe. It cured the issue.

Never had that happen once even at 200 plus FPE check probe to make sure its not undersized.

[Motorhead]

This STUCK at home thing has me fiddling more on the RAPTOR FTS that I likely should be .. it was shooting just fine !
But alas always the tinkerholic never leaving well enough alone.  My excuse was R&D, yes lets see how that excuse fly's

Lighter hammer, MUCH lighter ... SSG devise as I've been using for a couple years now ,,, JUST GOTTA DO IT .. so i did it.  Lol
Manufactured an 100% Delrin ( Not acetal ) hammer that retained basic shape and buffer adjustablity. Finished up with buffer and cocking screws in place @ 25 grams. This is less than half the weight of OEM hammer.
Tossed it in with the same HST and buffer screw positions .... MORE power than it had before jumping from @ 800 fps to 870's  Well ok then, faster strike from the lighter hammer equates to lift happening faster is my WAG   
Dial in even slacker HST ( already in free flight ) the power "Kinda" falls away some. darn Reg pressure gotta go lower !!  or we need to loose some spring energy and that OEM 12# spring for this tune with a lighter hammer has got to go.     So .. lets make an SSG device and get a better handle on spring energy delivery.  Using the OEM HST parts simply placed a long 3mm screw threw the hole, make a containment hat for the end of screws threads to hold the other end of spring and put in a much lighter 6# spring from an M-rod.  Give it @ 1/4" of preload and install it, setting the free flight gap to @ 1/16" or so.

Load a pellet and SNAP being 720's or so with the reg sittin @ 1200 psi.   Curious where in the bell curve i was cranked up the pressure on reg and low and behold speed came up too. So my hammer strike energy is still excessive being I was getting more speed with more pressure.   Once at @ 1400 psi we're back at 800 fps.  At @ 1500 we peak @ 840's & start loosing speed ( so there's the peak ) dialed back to 1400 fiddle with the buffer adjustment to find just where reducing poppet lift starts taking away speed an move it back just enough to be in the sweet spot.   797/795/801/789/793/800 is the @ random pattern we see over the chrony. ( We're still hanging onto an @ 12 fps spread ) 

In making the hammer payed attention to sizing it for a better fit within the tube. OEM hammer was @ 1.040" where tube I.D. was 1.056" giving a .016" clearance which for a match rifle where we want the lowest cyclic vibration is excessive IMO. New hammer sits in the tube with @ .006" clearance.  Length of the hammer had to be reduced by @ .040" to get rocker catch sear to reset correctly with the snugger fit. No harm no foul.

End result .. Gun cocks far easier ( 12# spring to a 6# ) Hammer simply slides better too.  Shot cycle an even crisper SNAP and muzzle report different too.


Thats about it ... until next time 

Scott S

[darren]

Scott...
You need an ERGO...ar15 grip for your netbooks....should fit those ape hands well and not expensive...look into it

[Motorhead]

We now have a SWING GATE style Single Shot Loader made ... Fat fingers and roll in trays were not working very well.
see: https://www.gatewaytoairguns.org/GTA/index.php?topic=171341.msg155926582#msg155926582

Also added some o-rings on the biathlon style cocking handle ... feels better and looks snazzy !

Quick couple pics ...

[KnifeMaker]

Man, I love that cocking handle Scott! Maybe I should look into making one. 


Now educate me. If the single shot tray is a roll in, how is it better than a properly set up mag? I have no idea.



Mike 

[KnifeMaker]

Oddly, the first bbl. I used, the TJ from JSAR blew the o rings over and over. Never more than a few shots before they would fail.


This is why I put the o ring on the probe. It cured the issue.

Never had that happen once even at 200 plus FPE check probe to make sure its not undersized.

Will do.

[Springrrrr]

Tinkers, please splane something to me /us.  We use the term "buffer" and "hammer" almost in the same sentence.

Is the hammer a separate item in the Raptor or is it part of the buffer?  I know about the adjusting screw about 3 1/2 to 4 inches in the tube and basically how it should be adjusted.  That seems to be what is known as the buffer, but is that entire unit considered to be the "hammer" also, or does the buffer strike a stand alone hammer behind it?

From Scotts post, I suspect they be in the same package.

[Springrrrr]

Shameful bump

Tinkers, please splane something to me /us.  We use the term "buffer" and "hammer" almost in the same sentence.

Is the hammer a separate item in the Raptor or is it part of the buffer?  I know about the adjusting screw about 3 1/2 to 4 inches in the tube and basically how it should be adjusted.  That seems to be what is known as the buffer, but is that entire unit considered to be the "hammer" also, or does the buffer strike a stand alone hammer behind it?

From Scotts post, I suspect they be in the same package.

[Motorhead]

Man, I love that cocking handle Scott! Maybe I should look into making one. 


Now educate me. If the single shot tray is a roll in, how is it better than a properly set up mag? I have no idea.



Mike 

Tinkers, please splane something to me /us.  We use the term "buffer" and "hammer" almost in the same sentence.

Is the hammer a separate item in the Raptor or is it part of the buffer?  I know about the adjusting screw about 3 1/2 to 4 inches in the tube and basically how it should be adjusted.  That seems to be what is known as the buffer, but is that entire unit considered to be the "hammer" also, or does the buffer strike a stand alone hammer behind it?

From Scotts post, I suspect they be in the same package.

Mike,
In the case of this .20 cal build .. there IS NOT a magazine for the the caliber and therefor must shoot it single loaded.  So as too a proper operating Mag / verses a Flip loader there are some advantages with THIN SKIRT pellets because a Mag & the spring that rotates the cassette always places a slight squeeze on pellet as it indexes ( actually a slight SNAP impact ) where a gate loader has the pellet simply sitting in a smooth hole and probe seats it straight in without any side load / impact.

Springrrrr,
The "Buffer" and "Hammer" are 2 pieces that work together. the actual buffer is just a 90 duro o-ring sitting between the back of valve body and face of the hammer. If or when the valve stem lifts so far the two collide and the lift stops at this point.  The "hammer" (AKA: Buffer Hammer ) has an adjustable striker screw that contacts poppet stem and is RECESSED within the hammer face. The distance the strike screw and relation to the o-ring buffer controls the actual poppet lift.  * So BOTH these parts would be included when one speaks of a BUFFER HAMMER.

Scott

[E30_S50]

That single shot tray is pretty slick!

[Motorhead]

Yesterday was doing further fiddling and while rifles holding a fairly tight ES in sequential shooting, if rifles sits for 10+ minuets or more the reg will creep up @ 50/75 psi and the next first shot was going 15-20 fps faster than wanted.
While I tried to get it tuned on the bell curve knee, these balanced valves are just so willing to make power that even a slight change in pressure has it making more / or less power accordingly.

SO ... took the Ninja adjustable regulator apart and pulled the inner spool removing bevels, o-rings.  Chucked it up in the lathe and trued it. That done using a small .155" end mill removed the OEM nylon "Seat Ball" leaving a slightly larger hole with a small ledge the NEW SEAT will shoulder on.   Out came the PEEK making a small cylinder that was then pressed into the end of spool, faced off very smoothly ending up at the same @ overall length of the ball seat there previous.   With a Cratex point polished the raised volcano rim of portion the peek would seal against inside the lower reg body.

Cleaned and lubed with a reassembly and a few shimming spec changes we have the regs low side at @ 1150 psi and high side +/- @ 2200 psi ... perfect.

Now the REALLY really really good news !!   With reg set to 1500 psi which gets my wanted 800fps IT STAYS AT 1500 psi dead nuts !! you see pressure gauge drop during the shot @ 200 psi and it instantly within a few seconds is back at 1500 psi.  Gun sat all night with 4000 psi in the bottle and came out this A.M. and it was still there ! ... took a cold shot over the chrony @ 801 fps.  Now were talkin !!!

** This is NOT saying the adjustable regulators have a problem, Not at all.   What I'm saying is for the JSAR RAPTORs to work as a high precision match power gun at these reduced power levels while also utilizing the Balanced valve the pressure the valve processes needs to be very very stable.   Looks like we're daily inching along in making this gun more and more refined which in good for the short term and Great for the long term with much hopefully carried over to production guns in the foreseeable future.

Scott S

[E30_S50]

Now that's some R an D right there!

[Jacob_M]

I also found this to be true Scott. If my rifle sat for long enough my first shot was always faster.

Since bumping my reg back up to 2000psi and trying to make power, it has become less of an issue.

It was definitely more problematic when I had the reg turned down to 1400psi and trying to shoot the .25 kings at 900fps.


When you say tuned on the bell curve knee, is that mean adjusting your hammer spring and buffer to get close to max FPS for given reg pressure?

[Motorhead]

When you say tuned on the bell curve knee, is that mean adjusting your hammer spring and buffer to get close to max FPS for given reg pressure?

 That would be correct ...

[Jacob_M]

Just realizing I knew the answer already, I guess I’m always just saying tuning to the knee.

Never quite say the whole thing, knee of the bell curve. And bell curve has me thinking of unregulated guns lol.

I got it.

[KnifeMaker]

Scott, I had my reg at 3000 psi yesterday testing more slugs. Last night I say that the reg pressure had crept up to 3500. Luckily, that is all the air I had in the tank pressure.


It later started leaking by the adjustment ring. (front end) I can't help but winder if I should try the same as you have done.


I'm gong to take it down and inspect in a few minutes.



Mike

[Motorhead]

Scott, I had my reg at 3000 psi yesterday testing more slugs. Last night I say that the reg pressure had crept up to 3500. Luckily, that is all the air I had in the tank pressure.


It later started leaking by the adjustment ring. (front end) I can't help but winder if I should try the same as you have done.


I'm gong to take it down and inspect in a few minutes.



Mike

I was actually surprised the amount / degree of seat impression the ball already had .. Regs only cycled less than 400 shots so far.  I know how tough PEEK is and having made reg seats many times with it have no doubt it will be long lasting.

[Motorhead]

We're a bit further along in R&D now ... Previously with some Reg modification replacing seat with PEEK we were able to shrink the ES the rifle was shooting.  Likely for most this would have been acceptable
Ya just never know if it can be better until you try, and knowing this Raptor Mini FTS is not for power but competitive consistency we changed up the valve to what is a more common and proven super stable configuration.

See: https://www.gatewaytoairguns.org/GTA/index.php?topic=172629.msg155944242#msg155944242

Scott S