Yes it will affect the zero, but the group could shift in any direction as you are changing the harmonics of the barrel. As Claret Dabbler says, you may be lucky and the shift could be tiny, but the only way to find out is to try it on a target.
If you have 'target type' adjustable turrets on your scope you should be able to zero the thing with mod on and then shoot a group mod off, zero it with mod off and note the difference. You can then dial in the zero for mod on or off depending on your stalking circumstances.
That I paid the expense for a screw-cut and a mod for my tikka's ! Why do I want to shoot without them!!! Zeroed in as I want it so, unless I want to make a big boom, why have I bothered to moderate!!!
I agree that they make you top heavy when carrying but with a Harris bi pod , or some decent sticks , why interchange !!Back to the Range for a comparison for me !!Coz honest I haven't compared.
(I know I should have done it already DUH)
I am of the same oppinion Trapper. I tested mine when I first bought it just to see. Haven't been out stalking without the mod. I have the 600mm barrel on my T3 plus a Jet z compact so it's a bit like carrying a pole vault pole about but with a ruck sack type sling it's ok.
If it shoots fine as it is then I would leave it on-(if it aint broke then dont fix it),
Be it right or wrong I leave all of my rifles with "can on", they only come off to be cleaned, they get hiked all over my New Forest ground shooting Fallow & on long hil stalks north of the "Big Wall"
After using a mod that works properly for you then I just cant see the point to going back to not using it & dealing with all that bloody recoil, noise & loss of target impact sight in the scope once again.
Having had most mods on the market at one point I do find that the PES end cans work for me better than the over barrel models.
If you are just having a gander about after a few fallow & clicking up a few km per stalk then I would leave it, in addition to the fact that fallow can at times be pretty silly when grouped at times - with the added benefit of a mod-you may get a chance of dropping more than one should you wish to, the most I ever had from a very large herd was 5 in number, I then ran out of bullets before they ran off at a rate!
Had the rifle not been modorated I am sure I would have only had 1 or 2.
Well chaps n Chappeses thought I would check zero with and without mod .
Some photos attached for perusal , just a bog standard Mod on/Mod off ,
mod was wildcat predator 8, I would say having gotten used to the mod , firing without again was kinda stone age, just my opinion.Grouped fairly well had to make some sight adjustments, as i had the scope off after march n shoot w/e. I must also add that after taking the mod off my first grouping never HIT THE TARGET!!!, that was with a kinda hot barrel so I waited 20 minutes ,and a quick pull through later I was back on target, fairly reasonable grouping , although low and right off centre. So for me there is definatley some change in grouping, well thats my waffle hope it hasnt bored you ,
Regards to all
I agree my first grouping on non moderated never hit the target at all regardless ! If that was a stag instead of a piece of paper , well he would be relieved , but I tend to get 1" groups down to 1/2 " that is on factory ammo , think Wallace and grommet might call that a Close Shave!!
They do tend not to hang around for the party .(not Wallace n grommet )whilst you check zero though, . For the beast and myself I would consistently like to drop on the spot , no errors no mucking about , so I guess we should all seek to improve our skills , check zero regularly. I was spot on last week but this week!!!!