Benjamin Bulldog zeroing

I'll just throw this out there..

The shotgun spread pellet pattern 'might' actually be caused by the type and/or weight of the ammo that you're using..

I have 4 PCPs in .22 cal that I use different grain pellets with.. only 3 of the 4 will work flawlessly with all weights..
They're all 'power level adjustable too', so that helps..
The 4th - even on the lowest power setting will spit the light weight pellets all over the place - It's ridiculous..
As soon as I figured out that it was a fps/power to weight issue, I threw some heavier pellets through it, 
and sure enough, the crazy shotgun pattern was gone, and it was back to pellet on pellet accuracy.
I only have up to a .25 cal, nothing 'big-bore' like yours, but..
I'm sure that the same concept/principle applies..

IF that's the case, you can either try lower power, if not possible - de-tune a bit, 
or, just try to use a different type of - or - heavier gr pellet, and compare..

Now back to scopes..

I used a CLife laser/scope combo on all of them to sight them in at home inside @ a 10 meter range/target..
No biggie - No problems..

Then I upgraded to a Discovery VT-T 6-24X50 optic, and the POI was wayyy off..
Basically, I ran out of turret 'clicks' for elevation, and would have to use a TON of hold-over.. Not cool..
The fix was to go with adjustable rings, but, even though the POI was 'off', pellets hit the same spot..
[Edit] Elaborating: The scope rails were 0 mil, none added for short / long range.

That said - I'd be more apt to lean towards power / pellet / weight issues vs. scope related..

You have a nice scope, so, was trying to think of other possibilities - using process of elimination..

Those things would be my best guesses with the info that you gave initially..

 

Sam -

PS: Were you shooting at the same distance you had originally sighted in for? Just curious..
I've laser bore sighted a few of my match grade / bench rest rimfire .22's, 
and once in the field, the scopes were still a bit off when actually fired..
After that, I gave up on those things..

First of all, what projectiles were you shooting? {Note that SOME lots of JSB pellets are undersize to the bore and do not shoot well.}

I have several .357 rifles and multiple other calibers but each rifle has likes and dislikes.

I have a Bulldog/Pitbull and I'm getting 3/4" groups at 100 yards and know others who are doing similar so YES, you have a problem but we need more information.

Shotgun pattern? Just how big is the group?

How clean is the barrel? New does not necessarily mean it is properly clean.

Fill pressure, tethered or un-tethered

Bullet: MFG, style, weight, diameter (sized .357 or .358?) Lubed or un-lubed

Is your scope optically centered and have you tested the range of travel on both windage and elevation turrets? Is it used (previously broken on a springer or too powerful centerfire?), or new and could have a manufacturers defect?

A simpler suggestion. Tell us what city/state you are closest to. Most likely you have another experienced air gunner in your area, who can work directly with you and resolve your issue. It is frequently faster than playing 20 questions and guessing.