Grouping MOD on/off

goldypurple

Well-Known Member
I currently own a Jager Sporting Arms MOD for my .308, and I cant seem to get it to group tightly with the mod on ( its like a shotgun but within 4-5"), without the MOD it will keyhole the rounds inside each other 1" or less.

is it the added weight on the barrel? throwing the rounds? anything I can try?

Rifle: TIKKA T3 Heavy barrel .308
MOD: Jager Sporting
AMMO: 150gr Federal copper lead free
Screwcut: 18x1 thread

tia
 

8x57

Distinguished Member
Just to save confusion don't you mean cloverleafing rounds with the moderator off rather than keyholing? Keyholing is when the rounds are going through the target side on.
 

Miki

Well-Known Member
What size is the hole through the center of the moderator ?
Are the baffles in correctly ?
Also if you push a cleaning rod up through the breech does the rod poke out the moderator in the right place ? (ie is it laying slightly below center not touching the mods end cap or high or off to one side - indicating that the screw cut is off-bore).

Sounds like a mod or mod alignment issue.
 

Woodsmoke

Well-Known Member
Is the barrel free-floating? If all else is well, it's perhaps possible that the weight of the mod' is causing the barrel to touch the stock?
 

VSS

Well-Known Member
Is the barrel free-floating? If all else is well, it's perhaps possible that the weight of the mod' is causing the barrel to touch the stock?
^^^ This, I should think. Probably not enough clearance - only just free floating without mod, touching with mod.
Just to save confusion don't you mean cloverleafing rounds with the moderator off rather than keyholing? Keyholing is when the rounds are going through the target side on.
That's my understanding too. Keyholing is something that you really don't want, as it's caused by a tumbling projectile.
 

Uncle Buck

Well-Known Member
As already said...sounds as though mod is at fault..T3 synthetic ?
It’s only floated 4 ins past the front
sling stud there are two small pressure points could be the weight of mod, but l doubt that, sounds more like mod or alignment or mod issue if clover leafing without mod.

85BF57A0-4A85-4C34-8548-4668F00D9AE1.jpeg

Atb Buck.

PS try another mod.
 

Klenchblaize

Well-Known Member
I'm not quite so dim as to deny the connection with a loss of hearing and gun shot blast; well at least not in the same manner as certain members adpot to climate change, but every time I see one of these "moderator problem" threads I confess to rubbing my hands with a certain glee!

Sad I aknowldge but there you go.

K
 
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activeviii

Well-Known Member
Harmonics.

The barrel has a different whip with the mod on, you need to tune the bullet to the mod.

Get a meter rule and hang it over the edge of the desk and twang the end. Now tape a couple pound coins to the end and do the same. Notice the difference.
Same happens with the mod on the end.

There are other things going on with the mod as well but tuning the round to the rifle set up is all you need to do. If using factory then try a limb save tuning bung as they can bring the harmonics back to an exceptable level
 

Edinburgh Rifles

Well-Known Member
any mod that alters accuracy (negatively) rather than just point of impact is not fit for purpose

tuning ammo for accuracy to a mod vs no mod situation is futile
No disrespect to the mod maker with so many mods on the market in the UK that do NOT affect accuracy either choose another or investigate further

one thing that can happen when working with custom moderators and close bore to calibre tolerances is an increase in group size when the bore is too small but not too small to cause clipping
I have done a lot of testing on mods out of spec
.243 through a ".22 rated" mod - 6.5mm bore - works extremely well
.25 through .22 rated mod - 6.5mm bore - can work but has shown to impact group size with longer bullets

Check the bore to thread concentricity
We have had several rifles that have threads cut to the outer diameter which drastically reduces bullet clearance

a photo of the end of the muzzle is usually enough to eyeball the issue!
 

Alex Dalgleish

New Member
Was it factory threaded or after market? The mod has to square up on the releaved shoulder and only the last turn does it tighten to sudden stop. What type of mod are you having the problem with.
 

army-medic

Active Member
Anything added to a barrel can affect the harmonics and thus group size.
But as mentioned above there are many mods out there that do not cause as much of a difference as you are reporting, which makes me suspicious of a baffle issue or the barrel no longer free-floating.

Hope you get it sorted.
 

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