Planet Airgun

General Airgun Categories => Maintenance, Modifications and Upgrades => Topic started by: Baggawind on March 31, 2020, 03:05:11 PM

Title: New reg
Post by: Baggawind on March 31, 2020, 03:05:11 PM
I own one of the Zbroia Kozak bullpups .  Nice rifle but , there is a well documented problem with the regs on these rifles , a fluctuation in velocity caused by the reg. Well, a couple of years back my old friend Dave Whelham of Airmasters sent me all the parts, minus body , to make one of his regs. So, given the lockdown we are having to endure , I decided to go ahead and make a new reg for the Kozak . I was also given two complete spare cylinders for the rifle by Matt at SureShot . Which meant I could afford to use one for experimental purposes. I had already modified the firing valve so all it needed was a new reg. This I have just done and what an improvement. I set the pressure at 80 bar - 10 bar lower than standard , and i,m getting superb consistency , 3 fps , and a steady 10.9fpe . Perfect.
That used up a couple of days , only six months to go  :(
Title: Re: New reg
Post by: Gambo on April 05, 2020, 07:20:59 PM
That used up a couple of days , only six months to go.........

.......before it needs refilling!! ;D ;D


Is the reg giving good SPC as well as consistency Mel?

Any pics please dood?  ;)
Title: Re: New reg
Post by: Baggawind on April 06, 2020, 03:06:11 PM
Sorry mate, no pics as it is inside the rifle. The only test i,ve done is over only ten shots . Seven of those recorded the same velocity , one shot was high and two slightly lower . Extreme spread was 7 fps. I ,ve yet to do a shot count . At the moment i,m busy making another pistol. Got to have something to keep the old grey matter working.
Title: Re: New reg
Post by: Baggawind on April 08, 2020, 11:12:18 AM
Well i,ve just done a bit of pellet testing , firing 74 shots. It used 100 bar - around 1.3 bar per shot , not good . But this is around the same as before fitting the new reg. I figure the excessive use of air must be , in part, due to the very long throat and transfer port . The throat in particular is very large and long. Nowt I can do about that  :(
Title: Re: New reg
Post by: Gambo on April 08, 2020, 08:44:02 PM
Yeah 1.3bar per shot is excessive, spesh as it is nowhere near the legal limit.

Is there the option/accessibility to sleeve the port down to reduce volume, or is it already narrow, and so making it narrower would choke the power too much?
Title: Re: New reg
Post by: Baggawind on April 09, 2020, 03:29:25 PM
I can,t see any easy way of doing that . I checked the test figures just after I bought the rifle and they seem to be the same . 120 shots from 250 bar down to 100. I,ll just have to live with it. I don,t even use the thing these days. I bought it for shooting from inside my car when one of my permissions was a field full of pigs . But, not long after I bought it the pigs were moved away to another farm . Just my luck.
Title: Re: New reg
Post by: Gambo on April 10, 2020, 06:00:02 PM
Yeah...... the estimated 120 shots out of 150bar is 1.25bar per shot......ever so slightly less air usage than what the reg'd rifle is giving.

So it seems the reg is doing very little to improve SPC (unless the factory figures have been widely exaggerated), but at least it is doing what it's doing well with regards to shot consistency. ;)
Title: Re: New reg
Post by: Baggawind on June 18, 2020, 03:19:33 PM
I,ve been in the man cave today, trying to improve one of the regulators in the spare Zbroia cylinder.  I,ve substituted the nylon valve seat for a brass one , fitted with a tapered seat made of Delrin. As far as i know no one has tried this set up. I have a lot of testing to do as yet , namely trying to set the pressure i want which involves a load of stripping , adjusting and re-assembling but , hey , got nothing else to do. I,ll keep you posted.
Title: Re: New reg
Post by: Gambo on June 18, 2020, 06:48:42 PM
Thanks Dood. ;)
Title: Re: New reg
Post by: Baggawind on June 19, 2020, 12:15:07 PM
Been doing a lot of playing around with this reg. It involves a lot of stripping and adjusting and a lot of air being used but, I think I may have cracked it. At the moment it,s sitting at 75 bar . All I need to do now is test it on the rifle . But i,m giving it a rest for now. Watch this space.
Title: Re: New reg
Post by: Gambo on June 19, 2020, 12:36:11 PM
75bar is quite low isn't it?

Most commercial full 12ftlber's run around 90bar reg pressure IIRC.
Title: Re: New reg
Post by: Baggawind on June 19, 2020, 01:12:10 PM
Yes, it is low but that is just the figure it arrived at after doing some adjustments. In have yet to determine how much i have to turn the adjust screw for any given bar reading eg. .005 thou , .010 thou etc.. i reckon 80 bar might give me a good enough pressure. I only need 10fpe for shooting rats. Remember i have to empty the cylinder and remove everything just to make one small alteration. Very time and air consuming , not to mention potentially causing damage to the o rings as they have to pass over threads in the cylinder. 
Title: Re: New reg
Post by: Gambo on June 19, 2020, 01:20:49 PM
Yeah........time and air consuming.......that always seems the way of things when tweaking PCP's.

It is very probable that You'd need less reg pressure if chasing 'only' 10ftlbs....as I've said the reg'd 12ftlber's I have all seem to be set around the 90bar mark.

Good luck with it Mel....if you get fed up walk away for a few hours or days until you are fresh.....working when frustrated with summat rarely ends well. ;)
Title: Re: New reg
Post by: Baggawind on June 19, 2020, 01:29:10 PM
Yeah, that,s what i,m doing. I,ll have another go tomorrow. Also, given the problems I had with the 3d printed mags i,m going to ask my dealer friend if I can try some of the Chinese mags he stocks. I,m sure i could get at least one to fit.
Title: Re: New reg
Post by: Gambo on June 19, 2020, 01:31:18 PM
Do you mean SMK mag?
Title: Re: New reg
Post by: Baggawind on June 21, 2020, 11:06:31 AM
Yes, my mate has lent me one but, unfortunately the hole through which the probe passes is too high. And i can,t remove any material from the breech assembly. Poo. I re set the reg again and now it is sitting at 90 bar. Over a 14 hour period it crept up 10 bar but from what i can gather , this is a common occurrence with a lot of regs. This is why no doubt a lot of shooters taking part in FT or HFT fire off a couple of blank shots before competing . I,ve yet to fit it to the rifle and assess the consistency.
Title: Re: New reg
Post by: Gambo on June 22, 2020, 10:38:37 AM
Bummer about the mags.

Yes regs can creep.......I would too if I was trying to hold back as much as 300bar!!

If at all possible, I've learned the hard way to always fire off a few shoots (PCP or springer) before a proper hunting. zeroing or target session, just to the wake the rifle up and get everything moving again.

Before starting this practice, I once had a tasty looking bunny in my crosshairs, but when I fired, the rifle (an FX2000) just farted and the pellet fell way short of the target. I hadn't noticed the inlet valve had leaked and the pressure had dropped until it only had about 30bar left in it. Gutted, end of my day's hunting trip.

Lesson learned....I now check the rifle's operation before venturing out on every foray.
Title: Re: New reg
Post by: airgunnut on June 22, 2020, 05:25:14 PM


If at all possible, I've learned the hard way to always fire off a few shoots (PCP or springer) before a proper hunting. zeroing or target session, just to the wake the rifle up and get everything moving again.

Before starting this practice, I once had a tasty looking bunny in my crosshairs, but when I fired, the rifle (an FX2000) just farted and the pellet fell way short of the target. I hadn't noticed the inlet valve had leaked and the pressure had dropped until it only had about 30bar left in it. Gutted, end of my day's hunting trip.

Lesson learned....I now check the rifle's operation before venturing out on every foray.
DITTO!!
Title: Re: New reg
Post by: Baggawind on July 03, 2020, 01:53:00 PM
Well that didn,t work. It turned out to be too erratic. Oh well, i,ll try making a new one from scratch.
Title: Re: New reg
Post by: Gambo on July 03, 2020, 05:19:49 PM
Persevere and you'll nail it in the end Mel. :)