Maybe I just did not give them a chance!

[UlteriorModem]

I just came in from a few rounds after work. Shooting the Benjamin NP2 'SBD' Mayhem.

I had run out of my favorite pellets the H&N Field Target Trophy's 14.66gr

All I had left were JSB Exact jumbo heavy Daiolo's 18.13

But hey its a magnum springer why not. I had not had great success with these pellets in the past. I had tried them but after a few rounds and a fair share of flyers I quit them and went back to other pellets.

Tonight It kind of started out the same but after about 12 shots the groups started tightening up!?

Did the rifle just get used to the pellets somehow?

20180924_180355 by Tom Whit, on Flickr

Top right (3" target) was the first group of about 10 rounds. Top left was the next group of 12 rounds.

The next three smaller (2" targets) were shot from right to left, all 12 rounds each.

A few flyers and twitches in there but not bad grouping from 20 yards from what I thought was a 'bad' pellet

No where near as tight as the H&N but now I haven't quite given up on the JSB's!

Any theories? I used the same position, benched, front bag for all shots did not move the scope.

[bandg]

My first thought was it looks like getting used to the feel of the gun.  But also could it be the shift in position necessary to lower the point of aim from the top to the bottom targets?  No mechanical reason for it I could think of unless the specific gun behaves that way with pellets in general-maybe shooting tighter groups as it loosens up.  But that is something you should have noted if you've shot it a lot.

I recall a small bore match shot many many years ago.  To try something different, I shot the kneeling position targets down the left side of the page then moved to center pair top and bottom and finally down right side of page whereas we normally always shot left to right from top left to bottom right.  My left 4 were dead center (unusually good for kneeling) then the 2 center opened a bit and finally the right 4 were average.  The very slight shift in position made the shots less stable as I shifted to the right twice and I never duplicated the success of those first 4 shots in any other match.  Possibly you changed position/hold/rest in going from higher to lower.

[UlteriorModem]

Good point but I forgot to point something out 

The target in this shot is laying on it's side. The 'top' of the target is to the right. Rotate it 90 degrees ccw for 'correct' orientation.

So the order in the correct orientation was top left, bottom left, then the 3 right from top down.

Pretty sure I had the same hold etc. Like I said benched with a bag (artillery hold) front only.

As to the 'feel' of the gun, I am pretty used to it after having shot 100's maybe a thousand round through the gun and can punch 1" targets from the same 60' with the H&N FTT's.

[Mole2017]

If I follow your introduction post correctly, this is still a new hobby for you, so it could be that simple--time and practice making you a better shot. I was slow in stretching out my range when I started--one hole groups at 20 yards? Forget it. But then 30 yards was the impossible range, then one summer I was doing headshots on squirrels at 40 and 45 yards--all with the same rifle, my CFX. I wouldn't have believed it a year or two before.

Even that was a few years ago. Along came the R10 last year and this past spring I was trying out for the NUAH club. Almost made it--100 yards is harder to see than it is to shoot with my set up.

[UlteriorModem]

Thanks I actually wish I could stretch it out some more. I might be able to get like 75 yards in my back yard.

Anything further I will have to go elsewhere.

[Back_Roads]

 I have noted that switching from a lighter or tighter pellet in  a piston gun the lock time will vary, and changes the hold/ shooting technique needed to assume the same accuracy that a lighter or looser fitting pellet delivered.

[UlteriorModem]

I have noted that switching from a lighter or tighter pellet in  a piston gun the lock time will vary, and changes the hold/ shooting technique needed to assume the same accuracy that a lighter or looser fitting pellet delivered.

Lock time?

[Back_Roads]

 It takes a little more time for the pellet to move out the barrel, so the mechanics of the piston may react slower and thus change the dynamics of where the perfect shot cycle happens.
 I find the longer it takes to expel a pellet the more important a light artillery hold is, along with follow through.
 P.S. just means you are getting better at it