Optimal Regulator Pressure

Discussion in 'Steyr' started by broekzwans, Apr 17, 2019.

  1. broekzwans

    broekzwans New Member

    Joined:
    Mar 26, 2016
    Messages:
    13
    Location:
    NL
    After looking around for a long time to find the 'optimal' regulator pressure I always seem to find the 85 bar as rule of thumb/golden number for .177 sub 12 ft/lbs. After being busy tuning for the past years I found that these golden numbers barely fit every rifle. I get that this forum is mostly UK based so be very careful not to violate any laws and some common sense is required :)

    A cumbersome way to tune is to adjust the regulator in steps of about 2 bar and install every time and do the tests. This means the testing will take weeks and requires exact placement of all the components each and every time. I do it in a different way which is described below.

    The items you need are:
    • A high precision regulator with a digital pressure gauge
    • A modified steyr air cylinder with a foster style fitting without the valve inside (to prevent effects of a sticking valve)
    • A brass cylinder to replace the belleville washers inside the regulator
    The digital pressure gauge is not on my external regulator at the moment since this is a way more compact setup and thus easier to take to the range and use it as a tethered fill station.



    I can imagine that the high precision regulator isn't something you have laying around in the house (in the Netherlands and Belgium a lot of people that shoot our 100 meter airgun competitions actually do have one laying around :p). I've done the modification to the air cylinder because I had one without the quick fill and got tired of unscrewing it every time for filling so I took out the pressure gauge and replaced it by a foster style quick fill (best fittings sell them with the M10x1 thread). For matches I have another cylinder with the factory quickfill.

    To get the steyr regulator to stop acting as a regulator I replaced the belleville washers by a brass inlet and unscrewed the nozzle a couple of turns. In this way the piston can not move and since the nozzle is out of reach it won't seal the regulated chamber.


    Now all you need to do is put the Steyr back together with the non-functioning internal regulator and quickfill cylinder and go to the range. While on the range you leave the external regulator pressurized and tethered to the cylinder while shooting. A criterium I use to find my optimum is to see at which pressure the groups are the smallest and the noise is reduced to an acceptable level (Steyrs have a tendency to bark like crazy sometimes at lower powers).

    If you have to buy all this it's not cheap but if you're part of a club with a lot of Steyr shooters I bet you can find an easier and cheaper way (group buy or whatever). This same technique will work for other airguns too but I just don't have pictures of them to show it. Important is that the internal regulator must be at the exact same place as when you normally use it because it restricts the flow from the cylinder to the regulated chamber. If this flow isn't restricted during a shot your results will differ a lot from the actual use case. All internal regulators shouldn't be tampered when set, due to the possibility of losing the seal, but there is a very nice topic in this section about resetting regulators :)

    Hope this helps :) Again, I do not advise you to violate your own countries laws. In the Netherlands we're unrestricted in power so this is no problem for me but a lot of countries do have restrictions so abide by these laws!!! Also do not go above 140 bar for those who are allowed to do so, this is an advice from steyr themselves to make sure the internals are still able to handle it without breaking.

    And to prove my point, I'm set at 92 bar at the moment (take some inaccuracy into account of the pressure gauge so use the same gauge for finding the optimum and setting the regulator!) instead of 85 bar..
     
    cloverleaf, skjutglad, garym and 2 others like this.
  2. C.Eaton

    C.Eaton Confirmed Anschutz Nut...

    Joined:
    Aug 9, 2011
    Messages:
    1,504
    Location:
    Hockley, UK
    Club:
    Springfield / TEGC
    Graham very kindly tested my Anschutz regulator yesterday after I found some debris lurking in the bellvilles (velocity was +/- 30fps) and he set it at 80 bar on his whizzy tester. It now works perfectly, is consistent and recycles instantly which is great. Last night I fitted it and first shot over a chrono was somewhere north of 730fps with a heavy which isn't good. Turned the reg down and I reckon I'm around the 65-70 bar region now and supremely consistent at 699-700fps, so a very happy camper...:D
     
  3. Peter Trimmer

    Peter Trimmer Member

    Joined:
    Aug 25, 2018
    Messages:
    38
    Location:
    Camberley
    I get a lot of bark from my pro target. Doesn't seem to matter if the reg is on 90 or up to 105.
    I will have to give it a go on 85
     
  4. chrisc

    chrisc Lucky git

    Joined:
    Apr 17, 2009
    Messages:
    2,968
    Location:
    Barnsley
    Club:
    Emley Moor
    I've started setting Steyr regs a little lower at 83/84 bar. I have done experiments in the past with 3 regs set at 75,85 and 95 bar. It was a flippin monotonous day swapping them over and then shooting a few hundred into groups. the results were totally inconclusive so i started to set regs around the 88 bar region as they were stable on the checker. When the newer regs came through with the different belleville configuration i was finding that these regs were nowhere near as stable as my 15 year old 6ftlb converted reg (small exit hole). When i get those i swap the bellevilles back to the old configuration, do my usual bits n bobs and set at 83/84 bar. I'm now finding that the regs are super stable with a quick pressure return upon firing. I serviced a Gents rifle last weekend and set the reg to 83.5 bar. The reg crept 0.3 bar in 24 hours and took under 3 seconds to get back to a stationary 83.5 bar after each shot simulation. If i had been using an analogue gauge you would have seen zero creep.

    Of course there's nothing wrong with trying to make a part as accurate as possible and i applaud anyone taking the time to do so and let everyone else know, but i suspect that you wouldn't see anything in group size with a reg that shifts a couple of bar between shots. I did go through a period where my no1 reg was failing for 20 or so shots and then coming good again which was a total git to fault find, it turned out to the be the larger piston o ring breaking down (although looking at the o ring through a loup it looked fine) but it was leaving a build up inside the reg body causing the occasional 'bind'. It's never done it since and it's now something i check for when servicing a reg but have only seen it once more whilst servicing maybe 3-400 regs.

    I personally think Steyr regs are pretty bomb proof. As an example my 15+ year old reg still has the original piston inside and has the original bellevilles and neck adjuster. That reg is super on the reg checker but it might just be down to have one with exceptional build tolerances. I'd like to say though that every 2 years i service my Steyr and swap over the regs so in reality that reg has probably had only 7 to 8 years total use.
     
    Last edited: Apr 18, 2019
  5. cloverleaf

    cloverleaf Active Member

    Joined:
    Sep 12, 2014
    Messages:
    304
    Location:
    Oxfordshire
    This is similar to the method I use to set up regged rifles, although I do so based on the velocity curve (reg pressure set to correspond to the peak of the curve once velocity has been set to an appropriate value using the striker spring adjustment).

    From a mechanical functionality perspective this is the correct way to set up the rifle - a lower reg pressure than this ideal will make the gun inefficient, noisey and possibly less accurate, a higher reg pressure will cause an off-reg spike (which in countries with muzzle energy limits could render the gun illegal).

    In addition if the reg displays any input pressure effect this will manifest itself as a gradual increase or decrease in velocity over a charge if the output pressure is set incorrectly, while both high and low settings will make the gun's velocity output more susceptable to fluctuations in reg output pressure.

    There is certainly an efficiency (and possibly accuracy..) argument for running the reg pressure high; however the viability of this is hampered by the issues described above.


    The accuracy testing angle is an interesting one, but raises the question of whether any improved accuracy is a result of the reg pressure itself or the corresponding velocity this just happens to achieve. Further to this there's then the question of how reg pressure affects accuracy when separated from velocity - I'm personally of the opinion that high pressures combined with large porting and short valve durations are the way to go as they'll result in more complete expansion of the charge in the barrel; meaning greater efficiency and lower pressure at the muzzle which should reduce noise and potentially-detstabilising muzzle blast.

    Unfortunately this is difficult to achieve without encountering the issues with high reg pressure set point described above, while using smaller transfer ports basically mitigates any benefits as this chokes flow and reduces effective pressure in the barrel despite the higher reg output pressure.

    Nothing's ever simple, is it..? :p
     
    Last edited: Apr 18, 2019
    broekzwans, paul.w and Peter Trimmer like this.
  6. broekzwans

    broekzwans New Member

    Joined:
    Mar 26, 2016
    Messages:
    13
    Location:
    NL
    nothing is ever simple indeed :D

    I test at different regulator pressures and different velocities at those pressures. Groups will look pretty similar most of the time but every now and then you'll find a node that is just a little better. While tuning I also look for signs like spiraling and the ease of becoming unstable. Before I had a regulator pressure of 120 bar, while being reasonably silent it had a tendency of destabilizing quite easily which resulted in not flying true in a straight line.

    I agree on the higher reg pressures being more efficient but the pellet itself should be able to handle those pressure correctly. Very thin skirts tend to blow up too much with the high pressure spikes and they will destabilize way too easy. The other side can be said on very thick skirt, they will barely react to lower pressures which makes it hard to create a decent seal in the barrel by the pellet.

    A lot of things to keep in mind while trying to find that ultimate sweet spot. And when you finally found it you just have to wait until you run out of pellets and you have to buy another batch.....
     
    andyfin and cloverleaf like this.
  7. Pauly5

    Pauly5 Member

    Joined:
    Sep 1, 2013
    Messages:
    34
    Location:
    NZ
    Club:
    Wellington Airgunners. (WAG)
    I feel I stumbled upon a great setup when installing a reg into my S510 carbine. Reg is set at 65 bar and fitted the lighter hammer and spring. Being an FAC gun I was able to open the TP right up using the power adjuster. I was setting the gun up for pest work and wanted around 11 ft/pd in 177 and consistant shots. Before fitting the reg I got around 40 shots complete with power curve, and after fitting I got 79 consistant shots from the same fill pressure (190 bar).
    I wish I could have had the time and patience to have done it more methodically, but I adjusted reg down until I got the desired pellet speed. So I wasted a bit of air, but did it in two bites, and as I say stumbled upon what I think is a great little set up for me.
     
  8. Bezzer

    Bezzer Member

    Joined:
    Nov 28, 2016
    Messages:
    92
    Location:
    N.Staffs
    Club:
    Kingsley HFT
    You can get better if you experiment with hammer weights, stroke, springs, reg pressure etc , my .177 400 carbine now does 120 shots at 11.4 fpe after making different bits and testing....lots of testing. (Lane reg left set at his standard 105 bar for .177 Air Arms with 3.5mm TP)
     
    Peter Trimmer and Pauly5 like this.
  9. Pauly5

    Pauly5 Member

    Joined:
    Sep 1, 2013
    Messages:
    34
    Location:
    NZ
    Club:
    Wellington Airgunners. (WAG)
    Hey that's a great result! Are you giving me the ok to buy a lathe and never come out of my garage? I had used a Lane reg too.
    Just remembered that I packed the valve spring out with a small spacer too, but Other than getting different hammer springs I didn't have tooling to change the hammer at all.
     
  10. Peter Trimmer

    Peter Trimmer Member

    Joined:
    Aug 25, 2018
    Messages:
    38
    Location:
    Camberley
    Increased the pressure on my pro target today and filled to 195bar. Got 80 consistent shots before it started to drop slowly as it came off the reg.
    Dead chuffed.
     

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