Testing Moderators on my Avenger 25
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Testing Moderators on my Avenger 25
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Topic: Testing Moderators on my Avenger 25 (Read 209 times))
JimD
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Posts: 1309
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Real Name: Jim
Testing Moderators on my Avenger 25
«
on:
September 17, 2021, 10:43:49 AM »
I got my other project finished yesterday and it stopped raining so I got a little shooting in this morning
. I got a couple of the Crosman trail baffles from Crosman and a piece of carbon fiber tubing and made up a couple simple, inexpensive moderators. I use a home made moderator on my Avenger that I've written about before. It has a central aluminum tube threaded to fit the Donny FL adapter's 1/2x20 threads, an outer tube of Schedule 40 PVC, and 3/4 plywood end caps. So I wanted to see how well both worked (seemed like a good excuse to shoot some). I set up one of my Chinese chronographs and got a shot string while I was doing this, the longest I've recorded for my Avenger.
I measured sound level at the front of my bench right by the muzzle - just because it was convenient to do it that way. Nobody but me would hear it at this level. The bare gun was about 104 db. With the Crossman baffle moderator I measured 101.6. It sounded quieter than that. A noticable reduction. With my moderator, it varied more but my eyeball average is 98 db. So it's quieter. I guess I will continue to use it. It is bigger in diameter so I have to take it off to fill the gun. I need to test what that does to group size (another reason to shoot!).
The point of impact with both moderators was lower than the one group I shot without a moderator. The Crosman was a bit lower than my home made one. I need to keep an eye on the POI, however, because it was lower than I am pretty sure I left the gun. Not sure what is up. May have an issue I have not seen before.
I was also curious exactly how many shots I could get off a 3000 fill. My regulator is set to 2100. I got 22 before it came off the regulator and the velocity of the next two (to finish the third magazine) was only 10 fps lower. For the first 22 shots, I measured 931-922 fps (2.69 std deviation). For all 24 I got 931-912 (std deviation of 4.24). At 33 yards there was no discernable POI impact of the last couple shots being a little lower. I would consider a 3000 fill to give me 24 good shots. The gun can be filled to 300 bar, of course, which if things stay linear should give me close to 50 shots.
Here's the shot string:
927 fps
927
922
924
931
929
926
926
926
928
930
929
928
926
931
922
926
922
927
930
927
918
912
I'm a little concerned about having to adjust the scope but I am pretty happy with the number of shots at almost 50 fpe and the low velocity variation between shots. Groups were not great but I had one sub 1/4 inch group, one about .3 inches, and most of the rest were about half an inch. At least one was about 3/4 inch. There is a light breeze but I don't think it affected things much. I shoot a little better when I am not writing down velocities and messing with the scope.
Update, put the pellet trap back on the top of the fence and shot a few more groups. First group was a 3 shot with the moderator removed between shots to see the effect. It was not much, group was about .6 inches. But the POI was much higher. Interestingly it was the same number of clicks higher that I started lower. So I put the scope back where it was and the POI is now back to where it started. I am not sure of this but I have a potential cause others might want to consider. I carried my Avenger by the shroud and air tube some today instead of by the stock like I usually do. The barrel band is just held in with grub screws. I wonder if handling it like this affected my POI. I will try to consistently handle it by the stock and keep testing it for POI change. Not great to have the issue but I guess it's another excuse to shoot!
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Last Edit: September 17, 2021, 11:24:38 AM by JimD
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Logged
USA, South Carolina, Lexington
Benjamin Marauder Pistol (Prod) tuned to 16-20 fpe
Sheridan Blue Streak, stock, about 14 fpe
Crosman 1377 shot as carbine and not modified about 5fpe
Air Venturi Avenger 25, current tune is 45-50 ft lbs
SPA P35 25, 45-50 fpe
SPA P35 22, 30-35 fpe
SPA P35 177, 16-18 fpe
Booder98
Plinker
Posts: 240
yes
Real Name: Robert
Re: Testing Moderators on my Avenger 25
«
Reply #1 on:
September 17, 2021, 02:53:19 PM »
My experience with a moderator on the 1/2 x 20 adapter is that it will drag the POI down. Which doesn't really surprise me. I like my Avenger but it seems to be a little twitchy about the POI. I usually shoot a group right when I start to make sure the POI is in the same place.
One thing for the Avenger owners regarding the barrel band. There are no grub screws in my barrel band. AFAICT, there are the two small screws on the upper part of the barrel band which AFAICT are connected to nothing, and a small screw at the bottom passing through the pic rail into the barrel band. This could be an artifact of my replacing the plastic stock with a wooden one, and maybe I need to make my own screw arrangement to help the barrel band hang on better.
Logged
USA, OH, Hilliard
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Testing Moderators on my Avenger 25