Replacement for the standard Walther LG300 regulator costs USD$250.00 Joe makes them in batches when he has sufficient orders... Have ordered one to fit in my new Walther LG300 Hunter. Will post a review when I receive and fit. Joe's email is: email@example.com BTW, this is the chap who assisted AA in the development of their regulators: http://home.comcast.net/~joekorick/personal.htm http://home.comcast.net/~joekorick/aa_article.htm The people at Air Arms have a definite engineering bias, and they re happy to admit that a solid part of the success of the Pro Target MkIII is due to the regulator designs of our own Joe Korick, a multi-talented engineer based in Vancouver, Washington. Joe is one of those guys who has enjoyed designing and building things for as long as he can remember â€“ it s really the creative side of the work that excites him, the problem-solving. Production work is something he can do when he has to, but it s not his first love. After a hitch in the Air Force Joe worked in a propulsion systems laboratory, running jet engines in a test cell and working with the project engineers designing test fixtures and the special tools required for the tests they ran. This work gave him his first real experience of R&D and confirmed his passion for it; meanwhile he kept on with his education and acquired a degree and a federal license for working on aircraft. As Joe says, â€œto this day I work on business jets as my primary source of income, and as a side line to my day-to-day work I design specialty tooling and equipment for aircraft maintenance; some of these tools I use to make my job easier and some I market to other aircraft maintenance facilities. Aircraft work gives you a pretty rich background, since of course aircraft maintenance deals with electrical and mechanical systems, hydraulics and pneumatics.â€ Are we starting to see where those Pro Target regulators come from, Gentle Reader? Add to that these memories of Joe s: â€œAs a child I loved shooting. For my seventh Birthday my father gave me my first BB gun. I grew up in Southern California and our home backed up to a big field which some nearby dairy used to grow feed for their cows. All that separated me from the field was a chain link fence. I got to shoot as often as I could coax my father out of his easy chair to supervise me in our back yard.â€ As Joe grew up he learned to enjoy shooting firearms as well, but like a lot of us he found it was a pain to have to go to all the bother necessary to find a place to shoot them. Airguns meant backyard shooting, easy for pest control and plinking. Then came that fateful moment we all know so well: Joe discovered adult airguns! Of course like any beginner he was interested in big power, so he ended up with an RWS 52 in .22 cal. (I remember that stage, too â€“ I can still hear the twangs in my head and feel my molars loosening against the cheekpiece). Step 2 was hooking up with like-minded airgunners, and soon he was lucky enough to find an active local club involved in silhouette and field target shooting. From there he developed his shooting and airgun collecting cheerfully until the day somebody showed up at a shoot with a Sportsmatch GC2 ... wow! Joe had to have a PCP! Unfortunately, the price was way over his head. What to do? Here Joe s background let him make a choice few of us could make for ourselves. Instead of a dead-end investment in a single gun, Joe turned the money around into a lathe and a mill â€“ he would build his own gun! He did (see photos) and one thing led to another â€“ soon he was making equipment for other airgunners. The move into regulator design grew naturally out of Joe s work on his first gun. It was clear that he was going to have to design a regulator for himself, so he took apart every gun that he could get his hands on and analyzed the regulator design for any flaws. He also read up on the subject and discovered that the design he wanted to expand upon had been widely used in the SCUBA diving field, which gave him a solid platform to work with. Fortunately, Joe was willing to share the story of his work on regulator design with U.S. Airgun s readers, so let s let him tell about it in his own words: â€œAs the regulator design was evolving it was necessary to build test fixtures that could cycle the reg and give information that was needed as to what was actually happening during the regulator cycle. Without the regulator checker it would be very difficult to determine what setting the reg was at or if there were any detrimental effects going on. The decision to use a particular valving system was based on several factors. I have always believed that simple is better than complicated. The more moving parts and seals there are, the more there is to go wrong. Also simplicity in manufacturing has to play a significant role. If it takes a long time to fiddle with the unit to get it working it would probably be too finicky for trouble free operation over a long period of time. Also ease of repair and seal replacement was considered. It is only a matter of time or number of shots before the o-ring seals start to wear and start to leak. The design I use only has two dynamic seals, which actually see wear from the moving valve. This limited the wear to these two points. The next consideration in limiting the wear was the travel that the valve moved from shot to shot. The other designs which I studied used coil springs to offset the air pressure. This had two drawbacks. 1) The coil spring had a lot of travel from empty to full setting, as much as .250â€. Also inherent to coil springs is that they impart a twisting motion as they are compressed and relaxed. This meant that the seals would see the valve rotating as it moved through its travel during each cycle. These were areas that I saw needed improving if I was to produce a more reliable regulator. I decided to use Bellville washers as my spring source. These are cupped washers made of spring steel. They were very strong and have an extremely long service life. They also do not twist during operation and the overall travel from empty to full was only .050â€. This was about 1/5 the travel of the other design. Which should equate to 5 times the life of the seals. I also reduced the diameter of the seals required so that there was less surface area exposed to the moving valve. Here again this equates to less wear and a longer life. This was the easier potion of the development.. Now came the hard part: the main seal which shuts off the flow of air to the regulated side of the valve. This is the most critical part of the regulator. There are a lot of detrimental effects which stem from this area. The biggest of these is â€œCreepâ€. Creep is the condition that occurs when the regulator does not stop the flow of air completely after the valve has shut. This allows the regulator pressure to continually climb over time. Some may climb a little, or it may climb to what ever the reservoir is filled to. It just depends on how well it seals the valve. A lot of testing was accomplished here until I came up with the material I use today. One thing is for sure; I now know a lot of materials which don t work! The next stage was to decide on the body of the regulator. Because I had reduced the size during the seal phase, I could now incorporate a larger secondary chamber into the design, which is required for higher energy levels of the US market. The trick was not to make it so big that it ate up valuable high-pressure air volume that would reduce the number of shots per fill, and still give enough volume at the regulated pressure to get the velocity required. The next phase of the development was the incorporation of the regulator into different guns. Precharges come in all shapes and sizes. The reservoirs are usually one of two sizes. 1 inch OD or 1 ¼â€ OD. So this meant two distinctively different reg body sizes. Except for one thing -- different gun manufacturers use different wall thickness tubing. This meant the reg bodies had to be able to be adjusted to changes in designs as they unfolded over time. For this reason I make the regulators in two oversized body styles and custom fit them to the particular gun they will be fit to. This insures the best fit possible. But it also means I have to do the installation. With a few exceptions the regulators, which I produce, are not for the â€œdo it yourselferâ€. This also allows me to keep a tighter control on the quality of the reg and the installation. As time has gone by gun makers have changed their designs to include external regulators. Typically, the user can install these. The first reg of this type that I produced was the regulator for the RN-10 from Air Arms. My goal here was to make a direct, screw in replacement, for the unit supplied at that time by Air Arms. Other manufacturers have also followed suit and are also using this same type of design technique. From my stand point this make my job of producing regulators for the ever-increasing variety of gun a bit more difficult. Unless there are sufficient numbers of people wanting these regs, each has to be hand made from scratch. The most economical way to produce these regulators is to sub contract the large production items to a company with computer-controlled machines. Actually, it wasn t long after Joe had begun producing regulators that the Air Arms connection took place â€“ the dealer who was importing the RN10 at that time was doing a conversion which involved installing a titanium reservoir and barrel shroud, but he wasn t happy with the regulator â€“ would Joe undertake an R&D job? Joe agreed, and the rest is history. Word soon spread to England and Nick Jenkinson got in touch. Joe sent over a couple of regs for Air Arms to test, and he was later informed that they had set up an automatic test fixture which cycled the sample regulator 35,000 times over a 2-day period with no failures. Air Arms didn t waste any time arranging a contract to use the design in their next generation of rifles, now familiar to us as the Pro Target Mk III/Tactical Hunter . Now Joe has expanded his approach to the widest possible range of PCP s, and besides Air Arms guns he can supply regulators for Daystates, Ripleys, Falcons, Anschutz, Feinwerkbau, Steyr and the Korean PCP s. Anytime a new model comes out, Joe goes back to his drawing board. R&D continues to be Joe s first love, so he does plenty of airgun-related work besides regulators â€“ in addition to his corporate contract work he handles requests from individuals who want particular pieces of equipment designed or modifications carried out on their guns. In addition he is working on targets, gun caddies, regulator checkers, special airgun tools, etc. For Joe, all this creative work is pure pleasure. If you have a project you d like to talk to him about, you can e-mail him at firstname.lastname@example.org one thing for sure, if he agrees to do it, you ll be getting the services of one of the most fertile engineering minds in the airgun field!