Umarex Accuracy dropped off after side lever install.

[The BB Bandito]

I recently put the side cocking lever from Maple on my Notos. So I can get quicker follow up shots when multiple squirrels are outside. After I did that the accuracy seemed to fall off. I was shooting around 3/8” @25 yds but now it’s spread out to 1” or so. I’ve double checked the scope and tightened all the bolts I see. I did have to take out the hammer spring during that install so that might be where the problem is. I’m not sure what’s going on? I’m pretty lost on this stuff.

I counted the turns when I removed it. When I installed it I verified that it was screwed in the same number of times. Unfortunately the gun is still shooting “loose” groups. I cleaned it too just for good measure. What the heck am I missing here? Currently I have the Hammer Spring 2 turns in from all the way backed out.

This is so frustrating to me. I have some data below for reference. I filled the gun between each shot set from a scuba tank that’s @2900 psi. I stop recording data when the tank reached 2000psi

Gun: Umarex Notos
Pellet: Jsb exact jumbo Diablo 15.89gr

1st shot set:
704, 708, 706, 710, 706, 706, 706, 707, 707, 705, 701, 705, 704, 707, 706, 705

2nd shot set:
708 , 709, 703, 703, 704, 710, 703, 698, 702, 699, 698, 702, 710, 716, 705, 708

3rd shot set:
718 , 715, 717, 722, 718, 716, 718, 717, 718, 721, 717, 714, 707, 703

 

[Hateful McNasty]

Don't reckon a alignment issue that could cause damage to the pellet when loading one up ?

 

[The BB Bandito]

Don't reckon an alignment issue that could cause damage to the pellet when loading one up ?

Everything seems pretty smooth loading. I feel like I would have to put some pressure on the cocking lever to damage the pellet. I double checked the clearances on the pins on the side level to make sure it wasn’t rubbing on the frame too and installing it. I also chipped the pellet probe for damage and didn’t see any.

 

[Normkel]

Everything seems pretty smooth loading. I feel like I would have to put some pressure on the cocking lever to damage the pellet. I double checked the clearances on the pins on the side level to make sure it wasn’t rubbing on the frame too and installing it. I also chipped the pellet probe for damage and didn’t see any.

Have you tried removing the side cocking lever/putting the gun back to the previous state?

If accuracy returns, you will have a cause to chase.

If not, something else is involved. The velocity variations are so small that I can't believe that the hammer spring/adjustment is the issue.... unless the velocities are significantly different than before. What were the velocities before the install?

 

[The BB Bandito]

Have you tried removing the side cocking lever/putting the gun back to the previous state?

If accuracy returns, you will have a cause to chase.

If not, something else is involved. The velocity variations are so small that I can't believe that the hammer spring/adjustment is the issue.... unless the velocities are significantly different than before. What were the velocities before the install?

Yeah that does make sense.