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In search of accuracy
Help guys! So I recently bought an L461 Vixen .222 off Kimber here on the forum. All looks pretty good, although the barrel (obviously a replacement as no engraving from Sako factory) is fairly worn internally and the rifling seems very shallow compared to all other rifles I've owned.
I put a new scope on it on Saturday and sighted her in at 50metres. I then changed targets and tried to shoot groups... Wtf?! I've always been a good shot (head shots on bunnies and pukekos etc at around 100m) and shoot respectable groups with my 6.5x55 and .22, but this .222 appears to be 'rising' in its point of impact with each shot.
I've heard in the past that .222 flogs out barrels quickly, and the barrel did get very hot very quickly with only a few shots. Is this why the point of impact would rise with each shot???
I'll put a photo up later, but a 'group of four shots was almost spot on for windage but 2" + for elevation!
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...as in rising 10-12mm with each consecutive shot
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Assuming you we're shooting off solid front and rear rests, and allowed the barrel to not get too hot, I'd say look at the action screws first, if not that the bedding.
As an interim solution, you can try to put some tinfoil between the action and stock and see if that improved matters.
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there may also be a point underneeth the stock where its contacting and as the barrel heats it moves away from that point
run it over a chrony to see if the heat from the barrel is causing the powder to burn more quickly and increase velosity
also does it return to original poi after it cools down for a while? that would point to the heat issue
alternitivly see if you can calibrate it to allow a dead on hold as a animal runs away from you
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Did you try different ammo? Might not like that particluar brand.
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Used Federal blue on weekend and have bought some Highland to compare.
I'll investigate further and try some of your suggestions over the next few days. Thanks for your input guys.
I spoke to Richard at Serious Shooters about it today and he made similar suggestions, but also recalled another .222 he had a similar problem with once, where copper fouling was the culprit. As the barrel heated up after each shot, it was spitting projectiles out all over the place up to 5" for a group.
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As above. Does it go back tp original poi? Scopes tight?
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I know it's tempting to try several of the options above all at once, but if you want to get to the bottom of it, change one thing, test, then change another thing... :)
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Saw that happening on a mates 223, turned out the scope was "walking" forward in the rings with each shot. Someting to check!
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An update for anyone who's interested... I dismantled the Sako and found the glass bedding under barrel hadn't been sanded very well and more importantly, the fore end sling swivel screw was pushing up the bedding to be in obvious contact with the barrel (Spot on @Bill999 ) I suspect this was the primary cause for 'rise'. So I've sanded it flat and all looks good.
The barrel was filthy too and a surprising amount if copper (and brass filings!) were removed to produce a respectable looking bore, so a huge improvement.
I haven't had the chance to shoot her yet, but will update with a photo of grouping once done.
Cheers
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http://img.tapatalk.com/d/14/02/23/9apehapa.jpg
This photo shows the first four shots 'rising' as barrel heated up at the main round target. The next group was shot into the square target AFTER I'd cleaned and sanded the defective glass bedding down. Much more consistent.
http://img.tapatalk.com/d/14/02/23/qequzana.jpg
So I smeared a berry onto the bottom of my target box and shot this at about 100yds... Happy, although next time I shoot may need to adjust windage to the right by a click
;)
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It's ready to slay goats when you come down now
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Thats the story. iv got a few norma and hornady .222 if you want to try some other factory offerings.