Huntsman Regal Huma reg 40 for .22 need help

[mubhaur]

Dear members,

I got a new Huntsman regal that has factory fitted huma regulator and it gives very consistent 19 shots at around 41 fpe.

Its .22 caliber gun.

I want to convert it into 30 ftlb version for reasonable shot count.

I opened it and reduced the length of plastic top hat that sits on the hammer spring.

Now I get from 860 to 885 fps on reg and after getting off reg there is a spike and it goes beyond 900 fps.

In order to eliminate spike,  I understand that I should reduce the reg pressure but I am unable to understand that why the spread while shooting within reg pressure range has increased from 4 fps to 20 fps.

I can see only one thing that the top hat that I cut is not very true and smooth and may be it causes each strike to be a bit different.

Please share if you have any idea about how to control the spread.

Regards,

Umair Bhaur

[AlanMcD]

The ES has increased because you have reduced the hammer energy, and thus moved the gun's performance on the shot curve.  Since you are no longer shooting a gun with the optimal hammer energy matched to the pressure in the plenum behind the the valve, the system is more sensitive to variations in pressure in the plenum.  No regulator is perfect at always delivering the same pressure - it is a mechanical system and there is some variation.

When the hammer energy is such that you would be shooting near the top of the curve for that pressure, you get less variation in the pellet speed from any given variation in the pressure in the plenum . . . .

If you want your tight ES back, you need to reduce the regulator pressure and re-tune the hammer to that pressure.

[nervoustrigger]

x2 on what Alan said.

If you try to reduce the velocity of a regulated PCP by changing only the hammer spring tension, what happens is the valve is no longer opening fully.  The elevated ES is logical if you consider backing off the hammer spring more and more.  At some point just before you reach complete valve lock, the valve is only barely being knocked open.  Very little lift and a super short dwell.  The effects of little variations in friction become magnified and the velocity spikes up and down.

An alternative to reducing the setpoint would be to leave everything as it is and choke off the transfer port.  Shot count won't be quite as good but for guns that have an external adjustment for the transfer port, it's really convenient for dialing the power up and down at will without sacrificing consistency.  I don't think the Regal has this feature but I wanted to mention it anyway in case it's handy on some future project.

[Motorhead]

Ideally .... having the tools to do so ( Remote ACCURATE pressure gauge fit between fill tank and guns tank. ) would be best done IN YOUR SITUATION by first reducing the spring energy on hammer a far amount before proceeding.  having a few springs of differing rate handy you may need.  During test you may need to go up or down in rate to find the sweet spot.
Then get the guns air tank drained down to 80 bar or so. LEAVE REG set point where it is at for now !

Hook up the gun to fill tank with gauge in the line. Fill the guns tank in 10 bar increments starting at @ 80 bar and take 2 shots over the chrony and write down pressure / speed.  Continue to do this watching where the speed plateau is and do a few 10+ bars past to confirm at what pressure the speed peaks.  *** IF THAT does not happen when getting to the pressure regulator is set for YOU STILL HAVE TOO MUCH SPRING.

IF by chance you can NOT get enough speed with pressure all the way up to the known set point, Not enough spring

Under stand you already know that at a pressure LOWER than current set point you can make more power than wanted, so it is just a matter of finding at what spring rate and pressure the gun will find the speed you want.

So now lets assume with a reduced spring rate that in your 10 bar incremental testing the gun hits your 865 fps target speed for 30 ft lb ( 18 grains ) at @ 110 bar and shoots slower at higher pressure  .... Now you have establish where the natural bell curve is.

Dump the air from test gear, dump the guns tank and dismantle removing regulator.  In a test fixture or what ever miens you have SET THE REGULATOR to @ 1-2 bar less than pressure you peaked at.

Set as such the gun will shoot at the prescribed speed, come off regulation at the same speed and even if you get a tad bit of reg creep letting gun sit ... THE SAME SPEED.
And ... you will find more usable shots per fill period.


My little tidbit of advanced regulation tuning technique

Good luck.
Scott S

 

[ranchibi]

karachi, if it is new, the regulator might take sometime to “settle in” in order to become more consistent. All the above tuners have given you expert advice, adhere to their recommendations! Congratulations on your new Regal! Enjoy 😊

[mubhaur]

Thanks to all who helped me.

Regulator pressure reduced to 130 bars. Hammer striker travel adjusted a bit and now the gun is giving 30 ftlb with 18 grain jsb.

Total 38 regulated shots with maximum spread of single digit.

Thanks to all.

Regards,


Bhaur