Tikka 223 not grouping after shortening

Hey Team,

Had a Tikka T3 223 1:12 shortened down to 18 inches. It used to shoot Belmont 55gr soft point just under and up to MOA depending on shooter. Obviously removed from stock and scope taken off before work done. Crown looks tidy as well.
Took to range today and it’s double grouping or not grouping at all.
The scope had rings left on when taken off so I just torqued back in same spot.
Stock was torqued to 35 inch/LB and then to 40 in case it was that. I’ve taken it apart again and there’s nothing touching barrel and aluminium lug isn’t loose or has any damage.
Tried some PPU ammo as well and that’s doing exactly the same.
I wouldn’t normally ask, but I know of so many that have been shortened for handy quad or ute guns that have shot fine after shortening and using Belmont. Also had a mate shoot it as well.
Any advice would be great.

You are correct, a short barrels is not less accurate. ShortENING however is a different matter, things can go wrong in that process.

My first thought would be that it might just do better with a different ammo, but you thought of that one already.

You have obviously had your rifle apart before and know how to put it together therefore, so not the answer.

Given that the muzzle end of the barrel is where it was worked on, have you had a magnified look at the crown? A good mobile phone camera on macro will often help, stuff a bit of toilet paper inside the barrel, 2-3mm back from the crown, for a better view (too far back and the camera focuses on the paper!).

Normally cutting a barrel with a good crown shouldn't be a problem. As per the norm check that everything is tight'n'dandy and also check the recoil lug is seated properly in the stock ( they are a proper cunt & can sometimes take repeated attempts to get em sitting right )

Would be worth taking a second scope next time you go to the range to eliminate that variable.

Little bit of a piss off but that’ll learn me for f&$king with perfectly good rifles.
What kind of things would I see with a crown that isn’t ideal?

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Originally Posted by McNotty

Little bit of a piss off but that’ll learn me for f&$king with perfectly good rifles.
What kind of things would I see with a crown that isn’t ideal?

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A bit like wondering what your left thumb should look like - take a clue from your right thumb. I'd expect each land and groove which you see end-on to look the same. The classic "target crown" is cut at 11 degrees, not sure why, maybe the angle does not matter to the bullet, but it does protect the crown a bit as it sets it back from the muzzle.

I'm not sure if there is no ready answer what the crown should look like, beyond even -- including on magnification. Out there on the net there is a joker who hacksawed an inch at a time off a new rifle and just removed the worst chips (no crowning), and she shot just fine after each mistreatment.

Thinking of mistreatment - were you a good kiwi and did you give the barrel a really good clean and remove all the copper fouling before sending to the gunsmith for the shortening job? Maybe just needs some light shooting-in now?

It most likely will be just the crown shortening the barrel willnot affect accuracy if done properly
Buy a Competent Machinist
Theres a few guys of here that have very old school 1950’s thorghts on here almost like it was what there grandpa told them its 2019 guys a lot of what was thought to be true in the older days has ether been proven untrue ot been invaded by modern technology a lot of this is to do with barrel lengths and or shortened barrel and it’s simplyNot true in this day and age
Every single centerfire rifle I have owned in the last 10 years have been shortened to 18-20” with no ill affect my creedmoor shortened from 24 to 20” will shoot 0.25” groups at 100 and I have mates with barrels as short as 13 or 14in barrels that are shooting sub moa at 100 yards and much farther

Now to fix your problem simply get a Confident gunsmith to recrown the rifle
Its a possibility that the Machinist that’s done the work has had his tooling slip in the barrel and fucked the last little bit of rifleing so he may need to trim another trim another 1/4-1/2” off to get rid of the damaged peice of barrel
But then you’ll be back in Business

The only negative effect of a Properly shortened barrel is the loss of a little speed normally arround 25-50fps per inch you shorten

double grouping=bedding not sitting right...some shots the bedding is touching one way.....some shots its touching another
also check the scope BASES...been caught TWICE by this both rifles had been to shop for work too come to think of it.
I wouldve though if it was a damaged crown rather than 2 OK groups you would be more of a shotgun pattern eg one big stuffed up group.

35-40lbs of torque seems like a lot. What do the specs for the rings and for the scope say?

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Originally Posted by PommyMcPomFace

35-40lbs of torque seems like a lot. What do the specs for the rings and for the scope say?

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He means action screws.

When did you last deep clean the barrel McNotty?

I had a similar problem yesterday, my normally reliable .243 shot like a shotgun, ten shots were 4-5" all over the place. WTF? Ran a boresnake through it, immediately after it shot 3 into half an inch. Carried on and the groups opened up again and the point of impact was way over to the left without me touching anything on the scope.

Deep cleaned it yesterday, it was pretty bad. Will shoot it this morning, see if it worked.

@Cordite @Flyblown was stripped out clean with Boretech, it would've had close to 50 rounds now through it while trying to sort things out.
I'll take rings and scope off again, redo those and check out crown.

Check that the recoil lug is seated in the stock properly
Im sure they are removable on tikka’s if it’s not seated properly down into its Recess it could be your issue also

I had a sako that would clover leaf at 100 with factory winchester
shortened it to 18.5 inches and it went to A4 paper sized groups
It may have been a bulge or something that was on that part of the barrel

gun got a new barrel at 18.5 inches and shot like a dream again
everything is a risk. most of the time its fine to shorten but not always

shorten it even more first
you have nothing to lose my ar15 wears a 12.5 inch barrel and shoots under an inch at 100m

or just keep changing brands of bullets till you find something that vibes with your current length

May be a bedding/harmonics issue due to taking weight off the barrel, rather than length. It does not say what stock you have, but a plastic stock can go silly over relatively minor bedding issues. They barely take the weight of the action and barrel at the best of times.

Id think its inch pounds not foot

The "Wind them up till the threads strip and the tube crimps" school of scope mounting uses ft lbs. Everyoune else uses inch lbs

Double grouping will likely be bedding. A poked crown will scatter shots.

The recoil lug can be a fiddle to get sitting right, give it a bit of a tap back in to make sure its seated in the stock properly and make sure the recess on the action is free of debris. When resetting it into the stock they require some shuffle and sometimes a bit of a bump to get seated properly.

Definitely inch pounds not ftlb

What rings are you using?
I used the factory Tikka rings for years with no issues, but replaced them with something else, then went back to the Tikka rings.
Found the rifle was hopelessly inaccurate, eventually changed the rings (again) and it was back shooting again.

I know used the talley light weights and they are great.

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Originally Posted by McNotty

Little bit of a piss off but that’ll learn me for f&$king with perfectly good rifles

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makes me think of an old saying
if it aint broken fix it till it is :thumbsup:

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Originally Posted by rambo-6mmrem

Definitely inch pounds not ftlb

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how about 12-inch pounds?

Attachment 105077
So....turns out someone (this dick) hadn’t tightened the locking ring on the front of the scope and it had a little bit of play.
Had all but given up hope till I found the same issue when sighting in 22 the other day.
Quick little rushed 5 shot group in fading light with Belmont. I’m one happy camper!!! PHEW

don't you like a happy ending

[ quoting Apollo: May be a bedding/harmonics issue due to taking weight off the barrel, rather than length. It does not say what stock you have, but a plastic stock can go silly over relatively minor bedding issues. They barely take the weight of the action and barrel at the best of times...]



If that were true about a T3 stock, how come they can hang a much heavier barrel off one and still shoot fine?

Have a look at Gunworks videos on youtube the girls did a clip on the locking ring.