European tuning disaster... help wanted

[Sjobee]

Good day to you all,

With amazement I have been following the different topics on gta and the tools and goodies you have available across the ocean is simply jaw-dropping ... The varity on SGS, HDD, light hammers, springs. From e.g. HILL, or JSAR, etcetera.

Over here in the Netherlands we have Huma and the official dealers selling stock parts.

So the question is how do I tune with the parts I have available?

I have a benjamin Armada .25 cal with a Huma regulator (with gauge port) set at 140 bar (2030 PSI) and I shoot the JSB 25.39gr.

The max I can get out of her is 245 m/s (800 fps). No matter how much I crank up the spring/preload. So assuming that would be the max. I turned it down about 4%. Meaning I shoot 234 m/s -  767 fps (although pretty consistently on the reg) untill it drops off and end up with shot 40 (219 m/s = 720 fps].

The 234 m/s shots are achieved with HT 3CW & HS 0CW and VMS all the way open 4 CCW. As said, more preload will only get me to 245m/s (HS 5CW).

What can I do? I ordered the Huma with XXL plenum. Ports and openings are all stock based.  I do not have the tooling and knowledge  to start drilling. Would not know where to begin and not sure if I would manage.

What options do I have? Apart from selling it and buying something else (which BTW is not my intention).
Are there channels, links in Europe, are there retailers who will ship to NL, or do I manage with the stock parts.

Help, anybody...

[Sjobee]

 

[Dairyboy]

Well I'm not sure on parts availability to the NL. However on the VMS all the way open is 5.5CCW so can maybe gain some there. Otherwise opening ports is the next step.

[Flatpicker]

Well I'm not sure on parts availability to the NL. However on the VMS all the way open is 5.5CCW so can maybe gain some there. Otherwise opening ports is the next step.

+1

I would bet the VMS is not fully opened.  Should at least one more turn open if not a turn and a half.  Transfer port shouldn’t be too hard to open up.  Lots of info on the MRODs here and marauder air rifle.com (leave out the spaces)

[Tucobenedicto]

Try to contact Gmac in UK,maybe they can help you to find or make a new transfer port,if needed.
https://www.gmaccustomparts.com/

[Sjobee]

Thanks so far...

I opened up the VMS 5 turns and I will put some pellets over the chrony.

BTW I saw ready to go Hill TP with .161 ID. I made another plead if he us willing to put some in an envelope put it in a bottle and throw it in the ocean...

Question: is .161 the way to go or .187?

I am reluctant at this stage to drill in the barrel and breech. Will opening the TP alone, add something to the cause?

I will check out the link to the UK.. thanks for thar

[Tucobenedicto]

I think you can go straight to .187, if speed goes too high you can fine tune with the VMS.

[Sjobee]

Just shot another string. Left everything the same except VMS, now 5 turns.

The first couple of shots increased with 5m/s (16 fps) and from shot 6 it was only 2m/s. And air consumtion was more.
So, using more air, without an serieus increase in fps.
Turned HS  and at:
2HS CW it was 243 (797)
4HS CW it was 245.7 (806)
6HS CW it was 247.4 (812)

Reg setpoint still at 2030psi

Quickly reviewer UK site, but found nothing of my liking

[Tucobenedicto]

I suggest you to ask here for an Armada owner,open a new post and put the model of the rifle on the title.
I am pretty sure someone can chime in.

[FuzzyGrub]

Question: is .161 the way to go or .187?
I am reluctant at this stage to drill in the barrel and breech. Will opening the TP alone, add something to the cause?

The exhaust on the Mrod valve is only 0.140" so having bigger TP, won't help much.  You do need to modify the valve to get more power at your current pressure.  Even just taking the exhaust, barrel port, and transfer port to 0.160, will help.  0.187" would be ideal, but the valve pocket needs some opening if you are going to that. 

[Motorhead]

Transfer path threw VALVE,TRANSFER TUBE & BARREL at @ .165" can be done using all the stock parts.
LIGHTER spring on the poppet valve.  Likely a tad lighter hammer in around the 35-40 gram weight.
Regulator set @ 135-140 bar and you should find a lot more power.

Scott S

[JimD]

If the Huma regulator is adjustable why not just turn it up?  I don't know anything about this gun but on my 25 caliber Avenger the regulator can go as high as 2900 psi.  I have mine set at 1600 and get almost 800 fps with 25 grain JSB or FX pellets.  I'm not sure I will ever take it to 2900 but I will try higher settings as soon as I finish messing around at the current regulator setting.  I am getting good accuracy and 35 fpe is plenty for at least near term usages (squirrels or targets). 

[Tucobenedicto]

Looking at the first post, no available tools, well,to follow the way Fuzzygrub suggested above you need only a 4mm parallel reamer and a suitable T handle.
If the valve port is .140 translated in metric is 3,556mm and 4mm is about .160
You can do the job simply by hand and the reamer almost eliminate the need to deburr the holes. this way you can enlarge the valve exaust without removing it from the tube too,just blow out the debrises.
Check on ebay,plenty of that kind of tools at reasonable prices.

[Sjobee]

You mean something like this?

[Tucobenedicto]

Exactly.

[Tucobenedicto]

One more advice,if you can find a 3,8mm drill bit,a first pass with it can help to smooth the work,not easy to find,but if you have a professional tool shop near you give a try.