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PostPosted: Sat Aug 20, 2016 9:36 am 
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Joined: Wed Jun 06, 2012 5:06 pm
Posts: 111
Location: Ontario
Ah yes Crossmen Destroyers... I went and weighed different tins and well, kinda odd, some are 6.3 gr and others are 7.7 gr, really odd considering the tins say 7.9 gr. The 6.3 ones are really below spec and almost as light as an alloy. I never used these pellets before and bought 5 tins of .177, 250, and 1 tin of .22

I will have numbers up soon


Last edited by niblixdark on Sat Aug 20, 2016 10:41 am, edited 2 times in total.

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PostPosted: Sat Aug 20, 2016 10:27 am 
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Joined: Mon Aug 08, 2016 7:23 am
Posts: 2779
Location: Somewheres near the Atlantic
I got one sitting in the corner waiting for D&L to get me a spring. 2-3 month wait.


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PostPosted: Sat Aug 20, 2016 10:38 am 
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Posts: 111
Location: Ontario
leadslinger wrote:
I got one sitting in the corner waiting for D&L to get me a spring. 2-3 month wait.


Check PM


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PostPosted: Sat Aug 20, 2016 1:43 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1271
Location: United States
25 is cool as long as you're ok with the velocity and the cost of ammo. I prefer the 22 since it's a great velocity/power match for that guns power level, but your gun your choice ;) Some people claim up to 30ftlbs in 25, which I assume used that seal I mentioned and were tuned but I don't the details.
When I sand the seal I try to leave at least .010" sticking out past the center so the metal would not touch. The last gun I used to test this kissed metal to metal when the seal was sanded down to ~.008" above the center, but a lot of factors will change that so not every gun will be .008. I generally keep them ~.010-.012" to be safe. If you dry fire it then no doubt it'll compress the seal much more and probably hit which would be much more damaging to the gun and scope. I don't dry fire so no worries, but if you do by accident or let other people shoot it which often do, then fyi. This is likely why the oem seals stick out so far, so imo it's basically a safety feature for the masses that costs us power.
That's crazy about the pellets. I've had some cheapies vary by .5gr or so, but never that much. One more reason to buy quality pellets.


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PostPosted: Sat Sep 03, 2016 5:15 pm 
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Joined: Wed Jun 06, 2012 5:06 pm
Posts: 111
Location: Ontario
OK I installed a new Diana ORING-28 Piston Seal in the Ruger Air Hawk and with a Ruger Air Magnum spring cut down to 34 coils, here are the test results below. I really wish I had alloy Stoeger pellets, 5.56 gr, to test. I will get some eventually, its the most fascinating pellet to test out of the bunch. I wonder how high in FPS the Air Hawk will reach with alloys now that I see the power increases with the leads running nearly hot. Anyone think 1300-1375 FPS OR 20 FT LBS with alloy is reachable? Well we're going to find out next !

Crossman Pointed Pellets 7.4gr

1039
1032
1049
1051 (18.15 Ft Lbs)
1034

Crossman Destroyer Pellets 7.7gr

1014
1028
1015
1025
1049 (18.81 Ft Lbs)

Stoeger X-Point 8.64gr

923.6
926.0
916.6
933.4
944.2 (17.10 Ft Lbs)
930.8
923.9
935.7
927.5
935.9

Diabolo JSB Match Straton 8.3gr

958.8 (16.91 Ft Lbs)
942.5
935.0
918.3
925.3
917.9
931.6
911.1
929.6
914.6

Here is a snippet of how the Ruger Air Hawk performs as stock.


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PostPosted: Sun Sep 04, 2016 12:51 pm 
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Posts: 111
Location: Ontario
Am going to test the Ruger Airhawk some more today with different pre tension loads from behind and in front of the magnum spring. I want to see if I can get CPP 7.4gr or CD 7.7gr leads to turn hot and run into the 1100 fps envelope. I'll post the results later on. (spring and piston seal not broken in yet either keep in mind.)


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PostPosted: Sun Sep 04, 2016 8:24 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1271
Location: United States
I think you're at your limit, but we'll see ;)
A broke-in spring will only be weaker. A seal generally doesn't break-in, not really anyway. The oil/grease may be contributing to fps too. I think you've shot it more than enough to burn it off but some people end up with a lot in there so it takes a while.
Did you sand that new seal thinner? They should sit lower than the oem seal but may still have room to sand it. Another bennie due to the different design of the O-ring seal is you can sand the dovetail down some, then the seal to match which will net you a bit of stroke. Not much but if you want max power you need to use everything you can.
Did you smooth and maybe radius the transfer port? Smooth the barrel (if needed)? Make a liner for the piston to smooth and dampen the spring? Use special lubes? Is the breech surface smooth so the O-ring can actually seal against it?


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PostPosted: Mon Sep 05, 2016 9:35 am 
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Location: Ontario
Everything but the spring and piston seal is stock. I did deburr and polish the insides and piston. I use 70% Vortec Moly on mostly everything but the middle of the spring, for that I use just plain black moly tar. I haven't done too much to the Ruger Air Hawk yet. I been busy with other projects but when I can get around to it, I will try some small performance mods. I won't be sanding this seal, it's not worth the small gain to me. I have 4 of these seals in my other airguns and I love them, they are awesome and for many reasons other then better compression, like quick changing the o ring for example. As for the port smoothing I don't know if that will actually help, it looks pretty decent as is to be honest. The breech & barrel face is smooth and shimmmed with new D-34 O-ring seal.

I think the only thing that will help at this point is to change the barrel out to a 20" or 24" I have done allot of barrel swaps on airguns and I believe I can get more in this way, probably a good 100FPS or more.

And yes am pretty close if not at my limits with it, once the spring is broke in I expect it to drop in FPS.


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PostPosted: Mon Sep 05, 2016 2:05 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1271
Location: United States
I don't know about your gun, but usually the breech surface and Xfer port are kinda ugly if you look with some magnification. If you think about how much pressure is at the breech seal, and how much air must past thru the port in a such a short time, it makes sense to clean them up. I also radius the inside of the port a bit, which also makes sense, at least in my mind. If it's worth the effort I don't know, but I'm pretty good at it so it doesn't take me much time. If I didn't do it then it would bug me and I'd wonder what if I had? Same with sanding the main seal, which I do not only for power but to reduce piston impact which reduces scope stress and no doubt barrel whip. If you can't see in the port, then take a drill bit that is the correct size and use it to feel your way down the port. In my experience the bit won't even go all the way thru because the other (inlet) end is too small. My guess is they use a worn bit and too much pressure/speed to drill it. I wish I could get a camera in there b/c it's horrible, and the opposite of what you'd want for max flow.
Not sure what barrel length you have now, but I would not expect anywhere near 100fps unless your current barrel is very short, like 15" or less. My guess is it's closer to 18? When I shorten an 18.5" barrel ~1" the loss is minimal. I can't remember how much but <10fps, maybe 5? Then losses increase the shorter you go. So based on that I believe ~18.5 is near ideal for a gun of that power level. Many people insist anything above 9-12" is too long and beyond that will cost you fps. I think they're crazy, they think I'm crazy... I've tested it, they base their info on tests done 40 years ago with very weak guns. Plus guns with shorter barrels continue to make less power than longer versions. So the theory of too long a barrel is correct, they just don't consider that power has gone up and barrel length with it. If a barrel was 30" then I'd agree it's too long and would cost power. What's the perfect length for your gun in 177 I can only guess, and I guess 18 is good enough. A pcp or similar would be a different story, but springers work differently so barrel length is limited by the time pressure is available.
Barrels are also a pita to make fit a springer, so I'd only do it to gain accuracy using a Lothar barrel. If a magnum gun then maybe some length might be worth it, but magnums suffer in power with 177 so they really need 22, and 22 doesn't need as much barrel. You also have the risk of a longer barrel flipping around more and possibly upsetting your poi more than the gains.
If you use a plastic liner in the piston then it'll be slicker, but also dampens the twang without tar. Tar costs power, how much depends on many factors. So imo it's best to use the liner and no tar no matter what, but especially so if you want max power.
Moly paste seems to be a good lube, but it's also very thick. The O-ring and piston have to plow thru that paste which is no doubt slowing it just like the tar is.
I think we discussed springs before? If not Vortek makes some that are stronger if you feel the urge, but stronger has drawbacks so imo spring strength is a balance. Kinda like a car eng, the more power you squeeze from it the greater the negs, like cost, gas, life span.
Either way I encourage you to continue tinkering and experimenting, which is what I did. I'm burned out on it now but I learned a lot which is more important to me than the performance gains.


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PostPosted: Wed Sep 28, 2016 1:09 pm 
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Joined: Mon Aug 08, 2016 7:23 am
Posts: 2779
Location: Somewheres near the Atlantic
I installed a new seal, and a 1000 FPS spring, I'm getting 855 FPS with 8.2 grn.


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