Something strange happened

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sigp220

sigp220

Member
May 12, 2018
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NE, United States
I was out hoping for a final sight in for the up coming hunting season. First gun spot on after 20 minutes I was tired of hitting everything I could find in the scope. Done and Done. Grabbed the R5M .25cal (huma reg, shooting 25 gr jsbs, zero setting at 32 yds, aztec scope and feeding off mag). I finally got it zeroed at 32 yards pulled up and shot at 50 yards. It's an inch high and will not group. It was pellet on pellet at 30 even shot a fly. At 50 ha two inches to the right and an inch high.

I'm lost is my scope screwed up, I am I pushing the pellets to fast, mounts not tight. Before you ask about wind the previous gun was a .22 shooting hades. I never even thought about the wind or hold over or under in that case.

I'm hoping someone is going to have some knowledge on this. My plan of attack is reinstalling the scope and rings. Then turning the gun down some. I believe I'm pushing 940fps with the 25gr jsbs.

Thoughts, or am I a dumb @ss and missing something simple?

Thanks
 
Shooting the pellets at 940 is a lil bit higher than most people shoot. However, a lot of people say they can get solid groups at that speed. If it was a matter of speed, you would probably be able to see the pellets spinning while they go through the air. If it seems like the pellets are flying straight without wobble then I would say check that the scope is mounted properly and leveled. If the scope is not leveled with the gun you could get it zeroed at 1 distance but when shooting at other distances the poi will shift in a similar manner you described. 
 
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If you have a shroud check the front to smke sure for some reason it's not clipping the pellet or if you a suppressor. I a gauntlet pushing 930 fps and I had to 3d print a new set fo baffle comes because it causing the pellets to spin and be inaccurate at 50 plus yards.
Click to expand...

That's a good point as well. I've got several moderators. Some dont group as well as others. And results vary across all my guns. Clipping (or coming close to clipping) will alter trajectory for sure 
 
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The Taipan Veteran I just picked up does something similar. I knew that it was set up to shoot the 34g JSB's at 840fps before I got it but I mostly have and shoot the 25.4g JSB's so I tried those first when I unpacked the rifle. It was shooting all over the place - we're talking about 6-8 inches off of my aim point in random directions with no consistent pattern. I thought it was clipping the moderator so I took it off - but it did the same thing without the mod. I was afraid something was wrong with the rifle.

Then I loaded the next magazine with the 34g JSB's and the thing is laser accurate at the same distance that the 25.4g's were spraying all over the place. So the conclusion I came to was that the rifle was set up to shoot the lighter 25.4's way too hot (probably 940+fps) so they weren't grouping. All of my other rifles are set up for the 25.4's because that's mostly what I have in stock but I may just leave this one as is and have one rifle that is set up for more power with the 34g's.

So try reducing your fps a little bit and see if that helps... 
 
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880 FPS is what JSB Kings will be MOST accurate at. Yeah guns can shoot them faster but at 880 fps is how I whacked a Crow at 172 yards or put them under a dime at 100 yards.

Your choke should be cleaned. A bore snake run through or just take shroud & monocore out and run some patches through but I’d use Hoppes #9 to get the choke completely “unleaded.”

Yeah you could be clipping. But I kind of doubt that or turbulence with your gun. 

You try single loading? Lots of times I’ll load each compartment from mag and push back out to see if mag edge is distorting anything.
 
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Fire some shots with the troublesome pellets at various ranges-20 yards, 40 yards, 60 yards, etc. and look for any pattern to the movement. Don't jump to the conclusion that it is velocity before you verify unless changing the velocity is very easy. Seems easier to shoot at different ranges to see what exactly is happening. If ANYONE else is shooting that pellet out of ANY gun at 940 with success then it seems saying too much speed for the pellet might not be correct. Could be that, could be something else.
 
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Okay, as per suggestions checked moderator for clipping. Nothing is evident. No bright spots, smears or otherwise.

I do have another baffle I will try.

I'm leaning toward spiraling. (Pellet not stabilizing). 

Tomorrow is a powder burner tuning day. I'm going to try and fit in a little airgun tuning also. I am going to fire the same pellets through a fx crown and see what happens. Just to take out a bad batch of pellets.

marflow, I did readjust the windage and elevation for 50yds. Never moved the power setting, but did adjust the focus also for yardage.

Thanks at least I know I'm not crazy now.


 
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My thoughts are LDC clipping issues from misalignment.
Click to expand...


Looking threw / down the barrel from muzzle end ... STRONG light source at breech, look at the light refraction as bore transitions into the LDC.

If there is an alignment issue you should clearly see it ... Even tho no witness marks of contact may be visible.
 
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Hmm if it was clipping or coming close, I'm pretty certain you'd see issues at 30 yards. Or maybe your gun just doesn't like the pellets? JSBs are quite soft. However, I really think it's the tune. Either too much hammer (valve open too long) or too much pressure on the reg. Is this a new gun/setup? 

I see similar issues on my crown if I'm over-powering projectiles. Mine is 22 cal, and I have to go all the way up to 36 gr before it'll settle down. Either that or turn the power down and shoot lighter projectiles. 
 
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First off Thank you all, took everyone's advice and all came out super.

Baffle changed, the stock baffle with a light source behind the breach end, looked odd. Kind of a partial eclipse in the 2 o'clock position. The aftermarket baffle bright light all the way around.

As previously stated turned it from 942fps down to 925fps. I backed the hammer spring out 13 clicks. (Edgun thing, it has positive clicks on the hammer spring, about an 1/8th of turn).

To the results, wind was a factor today though. When I did my part. My largest 10 shot group at 40 yards was the exact size of a cigarette butt. I happen to be burning one when I walked by so I poked it in the hole. Then back to the bench. At 40 yards I shot the filter out of it. I even managed to leave the paper. When I was finally happy with the scope settings I was shooting wild sunflower heads at 75yds.

The tune is definitely for 25gr pellets. The mkII's had a 3 inch drop at 50yds.

Once again Thank you to all that helped. This is an awesome forum!!!


 
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The "STRANGE" continues. After last weeks results I was excited to head out on Saturday. Turned out now I'm more confused than before.

I did nothing between last weeks tune and Saturday. Point of Impact shifted, groups were wild, I'm talking high and to the left but pellet on pellet then the third, an inch low.

Completely frustrated I headed home. As noted above, I opted to clean as my next step. On to today's results fired about 10 rds and it settled in. But still experienced the same odd shifts. It would shoot good for a couple of shots then shift. The best group at 50 today could barely be covered with you thumb.

Hopefully a few of you are still following this post and can offer some ideas. Here's where I'm going to start: Ordering another baffle, then I'm going to remount the scope (inch pound toque wrench will be in tomorrow), after that I might switch out the scope and recheck the regulator.

Dave from diller
 
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