.40 Badger

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Quad82

Quad82

Member
Jan 23, 2017
871
159
Michigan, United States
I hope I got this in the right place. Didn’t see a big bore section. I have been shooting my Badger at 50 yards tethered to a Air Venturi tank. It has a regulated output of about 2600 psi. I am getting constant 3 shot groups touching using 232 grain Air Venturi cast slugs. Very happy with accuracy. But when I shoot untethered, I get a lot of vertical stringing. I realize, I will get that as volicity decreases. But on a 4500 psi fill, my first shot is inches high and the next 2 or 3 shots are touching the bullseye. I am shooting over a chrony and that first shot is useally 50 fps slower then the next 2 shots. I have filled to 4500, 4300, 4000, 3500 and even just 2600 just a fill from my tank. All first shots are high. I have the same issue at all yardage’s. I am using a Shoe Box compressor to fill both the tank and rifle. For 3 of my last 3 shot strings with a fill of 4500 psi, I average 742, 768 and 734 fps. I have not filled to 2600 shoot once, fill to 2600 shoot again and fill to 2600 and shoot a third time to see if it shoots the same as being tethered did. Any ideas? Thanks Darrell
 
Seems like a typical unregulated shot string. I would fill to the gun where the 2 or 3 shots are most consistent. The reason the first shot has a slower fps is because the hammer is trying to overcome the higher pressure in the tank acting on the valve. As the pressure in the tank decreases, the hammer doesn't have to fight the valve which increase the fps. Unfortunately, most big bore air rifles need to be unregulated to get the higher power needed to launch a heavy projectile. 
 
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Thanks for the reply. I understand the shot string. But the first shot is hitting higher at a lower volicity. That is what doesn’t make sense. As I have mentioned, I have tried at several fill pressures and I get the same results. I get 1 lower fps bell curve type shot that hits higher then my next couple shots that are going faster. Here is a string I shot tonight at 50 yards. 
fill=4500
1-696
2-738
3-710
H=738
L=696
AV=714
42-21
End=3000
shot#1 was the slowest shot and it hit high by 3” at 50 yards
shots 2 and 3 hit dead on. 
Shot#1 going slower should have hit the lowest. Not 3” high. 

Here is a condensed string at 4000psi fill
1=683, 2=730, 3=719. H=730, L=683, AV=710, 47-24
Again shot#1 hit about 3” high at 50 yardsAnd shots 2 and 3 hit dead on.

I also have a string at 4300psi fill that is within a few fps as the other 2 strings. 
Fill pressure does not seem to effect the outcome. 

I think 3 times I need to fill to 1 pressure and shoot 1 time each and see if my poi changes.
 
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"Quad82"Its 715fps +/- 5fps for as long as my small 45000 psi tank will last. Then it drops speed as it should.
Click to expand...
OK so 4500 and 3 shots goes - 696, 738 and 710. 4000 goes 683, 730 and then 719. And just filling to 2600 gets 715?

What is your pressure after the 3 shots starting at 4500? and after 3 shots starting at 4000?

If you are still getting 715 at 2600 I would start at 4500 and keep shooting till you get to 2600 and record the string.


OK - pulling up the manual the manufacturer indicates a MAX fill of 4320 so I would start at 4320 and shoot a string till you are down to 2600 and show us the string.
 
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"BigTinBoat"
"Quad82"Its 715fps +/- 5fps for as long as my small 45000 psi tank will last. Then it drops speed as it should.
Click to expand...
OK so 4500 and 3 shots goes - 696, 738 and 710. 4000 goes 683, 730 and then 719. And just filling to 2600 gets 715?

What is your pressure after the 3 shots starting at 4500? and after 3 shots starting at 4000?

If you are still getting 715 at 2600 I would start at 4500 and keep shooting till you get to 2600 and record the string.


OK - pulling up the manual the manufacturer indicates a MAX fill of 4320 so I would start at 4320 and shoot a string till you are down to 2600 and show us the string.
Click to expand...
I have every shot so far dockumented. Every target has a shot string to go with it. So I have the start and end fill pressures of 3 shot groups. 4500/3000, 4300/2600, 4000/2300. Mind you, I am just doing my best to read between the lines on the gauge. I have an Air Venturi male/female in-line gauge sticking off the the fill probe. I leave it there so I can tell when to kill the compressor. I also use it to test/check the hand pump gauge. Both are pretty close to each other and the one I installed on the Shoe Box. 

 
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OK so it looks like the only number out of wack is the shot where you start at 4K and get 683fps.
Otherwise an estimation of the #'s is below when combining the strings (other then when you mention 4500 and average 742, 768 AND 734 as not sure where that fits in)

4500=696
4000=738
4000=683
3500=710
3400=730
2800=719
2600=715

Not knowing the height of your scope or the weight of your slugs, or the BC of your slugs will affect the trajectory calculations.
Pretty sure your low velocity shots could be hitting high due to the 50 yard sight in being on the "downside" vs the "upside" of your trajectory curve.
 
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I mounted the new scope at lunch and shot a 5 shot string. I did not sight the rifle in. Just went by the 50 yard group. 

232 Gn
Fill =4300
Shot#1 = 754
Shot#2 = 786
Shot#3 = 766
Shot#4 = 712
Shot#5 = 635
End= 1900
H= 786, L= 754, Av= 768, 32-16

Shot#1 is 2 3/4 inches higher than shots 2 and 3. Shots 2 and 3 are touching. Shot #4 is almost touching 2 and 3. Maybe 1/2” lower. shot#5 is about 2” lower yet.

i got a new mold and plan on casting some new 175 gn slugs tonight. Will play around and report back.
Thanks for all who help brainstorming on this. My son and I are very heavy into reloading and keep good records on everything we do. He is a U of M mechanical engineer who is into to metal whatever and making bullets. So this is one of those unexplained glitches that is killing both of us. 
 
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"Quad82"I mounted the new scope at lunch and shot a 5 shot string. I did not sight the rifle in. Just went by the 50 yard group. 

232 Gn
Fill =4300
Shot#1 = 754
Shot#2 = 786
Shot#3 = 766
Shot#4 = 712
Shot#5 = 635
End= 1900
H= 786, L= 754, Av= 768, 32-16

Shot#1 is 2 3/4 inches higher than shots 2 and 3. Shots 2 and 3 are touching. Shot #4 is almost touching 2 and 3. Maybe 1/2” lower. shot#5 is about 2” lower yet.

i got a new mold and plan on casting some new 175 gn slugs tonight. Will play around and report back.
Thanks for all who help brainstorming on this. My son and I are very heavy into reloading and keep good records on everything we do. He is a U of M mechanical engineer who is into to metal whatever and making bullets. So this is one of those unexplained glitches that is killing both of us.
Click to expand...
Based on your velocity shots 1 and 3 should be touching with 2 and 4 close by. Definitely doesn't seem to be a velocity issue.
 
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As someone suggested, figure out at what pressure your 2-3 consistent shots begin and fill to that pressure. Or dedicate one of your upper mil-dots to shot #1, haha.

The higher POI of shot number 1 is because of its lower velocity. Sounds counterintuitive, I know. The bullet is exiting the muzzle later in the shot cycle so you’re actually aiming higher at the exact moment it leaves.

Hope this helps(?)

Brian
 
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"Brian.in.MI"As someone suggested, figure out at what pressure your 2-3 consistent shots begin and fill to that pressure. Or dedicate one of your upper mil-dots to shot #1, haha.

The higher POI of shot number 1 is because of its lower velocity. Sounds counterintuitive, I know. The bullet is exiting the muzzle later in the shot cycle so you’re actually aiming higher at the exact moment it leaves.

Hope this helps(?)

Brian
Click to expand...
But #1 is alos the closest in velocity to #3 so why aren't they the closest to each other?

My opinion is it has nothing to do with the FPS, it is some other factor. Maybe even "operator error"? You get up each time to fill the gun? You pick up and move the gun to fill?
 
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Maybe I have not explained it well enough. It has not mattered what my fill pressure has been. Weather I fill to 4300, 4000 or even 3800, my first shot is slower than shots 2 and 3. But it always hits higher on the target. I understand you should only get a short bell curve when you fill past what the valve will handle. But I have gotten one at each fill pressure. This has to be false I know. But the target clearly shows this. I have let the rifle cool down after the fill up. I have taken up to 15 min between shots just to eliminate the “hot barrel” possibilities. Ya, I am laughing at this too. 
 
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"Quad82"Maybe I have not explained it well enough. It has not mattered what my fill pressure has been. Weather I fill to 4300, 4000 or even 3800, my first shot is slower than shots 2 and 3. But it always hits higher on the target. I understand you should only get a short bell curve when you fill past what the valve will handle. But I have gotten one at each fill pressure. This has to be false I know. But the target clearly shows this. I have let the rifle cool down after the fill up. I have taken up to 15 min between shots just to eliminate the “hot barrel” possibilities. Ya, I am laughing at this too.
Click to expand...
I think maybe your testing is not precise enough.
1 - Get a 3" gauge so you can get the precise pressure readings
2 - weigh all of your ammo prior to shooting to insure they are w/i 1-2% of each other


 
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I also thought maybe my crony might be acting up. Be we shot hundreds of shots over it this weekend out of the .243, 6.5 creedmore, 25-06, 270 and even the Mrod with no issues. Like I said, we do a lot of reloading and experimenting. 

Operator error? I wish it was. I could live with that!

Going to be busy the next few nights butchering deer. So I will do some more testing this weekend if the rain lets up.

Thanks guys
 
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