GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Lostcoast on May 22, 2017, 01:59:03 PM
-
I just bought a used Discovery and want to proceed with some mods for it. I was going to purchase a Power Adjuster from DiscosRUs and then heard of the SSG debouncer thing. Does a power adjuster do the same thing? Do I need both? If both, where can I find an SSG?
Thanks,
Kevin
-
.22 or 177 discovery? I have a .22. What are you trying to accomplish with the mods? Do you have a chrony?
-
It is a .22 Discovery. I will be trying to maximize power, accuracy and shot-to-shot consistency. Shot count is important but not as important as the other performance markers. I will be filling from a carbon fiber 4500 psi tank and since I have heard it is safe I plan to fill the Discovery to 2500psi or so. More, if that seems better for performance.
I do have a chrony.
-
I would run an initial chrony from 2000psi down to 1000. If you plan on fill pressures higher than recommended I would go ahead and get the high-strength screws for the valve from Magnum airpower. I bought the disco's R Us power adjuster and a couple of stock disco Springs. I also got the brass trigger and two screw modification from Baker airguns. At this point in my mods I got 24 shots at 23 fpe and 845 fps average.
It is a .22 Discovery. I will be trying to maximize power, accuracy and shot-to-shot consistency. Shot count is important but not as important as the other performance markers. I will be filling from a carbon fiber 4500 psi tank and since I have heard it is safe I plan to fill the Discovery to 2500psi or so. More, if that seems better for performance.
I do have a chrony.
-
You will need to clip a couple coils off the stock spring for the power adjuster to be effective. I also bought a stainless steel fluted hammer and stainless steel hammer pin. Then converted my disco to multi shot with a BNM multi shot breech and shroud and am waiting on delivery today of a Boyd's Gunstock to make a better fit. I can pm you my phone number if you want to talk in detail about mods.
-
Thanks very much, Phil. Talking about your mods would be great. I'll be available tomorrow and thereafter. Let me know days and hours that are good to call you.
-
Make sure you upgrade the valve screws if you plan on going over 2000 psi
-
Make sure you upgrade the valve screws if you plan on going over 2000 psi
Can I get the replacement valve screws at a hardware store or is this a specialty item that I need to get from a vendor?
-
Make sure you upgrade the valve screws if you plan on going over 2000 psi
Can I get the replacement valve screws at a hardware store or is this a specialty item that I need to get from a vendor?
No Sir! Google Magnum Air. He has is all worked out for you thru extensive test to failure. They are very high tensile strength, And the price is very reasonable! ;)
Knife
-
Do not exceed 2000psi until you get these screws. http://onlinestore.magnumairpower.com/products/discovery-valve-screw-kit (http://onlinestore.magnumairpower.com/products/discovery-valve-screw-kit)
Yer welcome!
Ed
-
Definitely do the mod before attempting to fill more than 2000psi. It's worth the 10 bucks for the peace of mind and a real simple install. Just degas your disco remove the action from the stock, remove the trigger group, remove the 3 original screws and replace with the Magnum airpower screws. You don't need to over tighten them as the screws fasten to the valve. I used a little blue loctite and snugged them up. I haven't had to fill my disco past 2300 psi as that is the starting point of my flattest string. I have it tuned now to get 25 good shots from 2300 down to 1300 psi. But I think the Transfer port that comes with the BNM breech is slightly larger so that helped me get to the velocity and foot pounds of energy I wanted.
Phil
-
Thanks, gentlemen - I will order the screws from Magnum Air Power today.
-
Regarding your original question about an SSG and/or power adjuster - an SSG is like a power adjuster setup with a built-in anti-bounce device as a bonus. So yes, in part they do the same thing, but the SSG takes it further, being adjustable while also deadening the return bounce of the hammer and thus preventing re-strikes of the valve stem. If properly adjusted of course. A well designed SSG should allow adjusting the gap between its end and the hammer and the preload on the striker spring. A power adjuster only allows adjustment of spring preload.
-
Is the SSG a part or assembly that I can buy somewhere, or is it easy to for me to make?
Re: Power Adjuster - is this also something I can make with hex screws and the stock spring or should I purchase an aftermarket product?
-
Sort of one of those things where if you have to ask... you probably aren't ready to make one. Why not take a look through the SSG thread and see if it makes sense to you? It's 45 pages, but worth skimming anyway if you're interested in the device:
http://www.gatewaytoairguns.org/GTA/index.php?topic=102095.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=102095.0)
I don't have your particular rifle so can't comment on how easy/difficult it is to fit either an adjuster or an SSG. But loads of guys do have them, and have done either device on theirs, many mentioning results and approaches in that thread.
-
Toss me into the 45 page thread instead of providing a helpful answer.. okay...
-
They are not hard to make. See photo below. Also someone on another forum named SteveNC sells them already done. I like the one I made better though. The silver part is a velocity adjuster, the screw is 8-32 with knurled nuts and I used heat shrink tubing for the spring guide. A lot of the 45 pages in the SSG thread is good reading though. HTH
-
I too search the 45 pages for the Disco SSG. Not easy to do. Any idea what page (s) yours is discussed David? Where does the modified hose barb fit in the scheme of things, sleeved in the adjuster cap?
-
You haven't been specific enough with your goals. The SSG will cause you to have less power, how much less depends on your setup, but will increase shot count if set up right. Filling to higher pressure will cause you to lose power and go into valve lock unless you go deep into mods like enlarging the transfer port, porting the valve and getting a heavier hammer spring. This will also cause you less shots per fill. Do you have any specific energy or shot count numbers you need to hit? You may end up ruining a rifle that is fine for what it is chasing a number that doesn't matter.
-
The modified hose barb is only to adjust the internal spring retention screw. This is how I adjust preload on the spring. I just filed a groove into the top of the retention screw and then formed the hose barb as shown because, well that's what I had on hand and it fit. The middle photo shows how everything is oriented inside the tube. My process was to use the preload adjustment screw to get the velocity a little higher than my goal, then place the knurled nut on the back to fine tune into my targeted velocity and watching the shot string extend and extend. The last post above isn't exactly right, you can adjust to have the same power as stock, but, it will extend your shot count by eliminating 'hammer bounce.' I do believe that people using a SSG typically like the extended shot count more than the power, so they (and I) adjust to extend the shot count and not to increase power.
-
Regarding extended shot count having priority over power; that's certainly been my main interest with SSG experiments, or at least shot count combined with consistent velocity. My QB78D with a 213cc Ninja bottle could give me about 60 shots at around 30fpe, but I don't want nor need that much power. 20fpe is plenty for grey squirrels and is the limit for HFT, so I tuned to about 19.6fpe and get more than 125 shots per fill in part thanks to the SSG. Of course the regulator in the tank also helps. The combination delivers such good consistency that I don't have to worry about what part of the fill I'm on, just take the shot and know the pellet will land where intended.
-
I appreciate your easy to understand description David. I'm bookmarking this with a plus. Yours is the way I'll go with my Disco. I've already done the power adjuster with many of the parts you show. I need to turn the end cap. Did you source your end cap or make it?
-
You haven't been specific enough with your goals.
You're right, Cliff - I reckon I have not been specific enough - my apologies to all. Such are the hazards of multitasking with a male brain.
My goal is to get in the neighborhood of 850- 875 fps with a JSB 18.3 gr pellet while maintaining excellent accuracy for as many shots as I can without losing POI. "As many shots as I can" meaning at least 20, if possible. I'm not certain if this is doable or not without going in the direction a double tube set up, which I don't want to do for the time being (mainly due to financial constraints).
I thought I would start a new thread on the topic of my Discovery Mod journey, in the hopes that I can learn from others and that others can learn from what I learn..
-
You can probably get where you want to be. I have seen some pretty good results from the members here.
-
Thanks for the vote of confidence, Phil. I will be calling you soon for your good counsel!
-
You haven't been specific enough with your goals.
You're right, Cliff - I reckon I have not been specific enough - my apologies to all. Such are the hazards of multitasking with a male brain.
My goal is to get in the neighborhood of 850- 875 fps with a JSB 18.3 gr pellet while maintaining excellent accuracy for as many shots as I can without losing POI. "As many shots as I can" meaning at least 20, if possible. I'm not certain if this is doable or not without going in the direction a double tube set up, which I don't want to do for the time being (mainly due to financial constraints).
I thought I would start a new thread on the topic of my Discovery Mod journey, in the hopes that I can learn from others and that others can learn from what I learn..
I think the first thing you need it's a regulator...this will bring you the number of shots you want plus the shot to shot consistency...after that you can install an SSG to improve the things even better...
-
Funds are pretty tight right now so a regulator is not an option (for now).
-
An SSG is not going to get the power you are looking for. It is difficult to even get stock 22 ft lbs without a super stiff spring in the SSG. You may be able to get 30 ft lbs with a heavy hammer spring and valve porting along with higher fill pressure, but 20 shots will be a stretch. Good luck with the experiment.
-
It doesn't sound like an SSG will be part of my mods for now. Thanks very much for the information.