I have just been shooting some Nosler 50 gr BT and sum 55gr VMAX through my Tikka T3 lite which is suppresed, with extremly pleasing results sub MOA its so close to one hole for three rounds it not funny!

But A WEIRD thing happened, I have been using American Eagle 50 HPs trough this rifle for a long time and they shot perfectly well to a certain degree.

I started using the Noslers & Vmax and my first two groups (one with each) went like a dream but they were 1.5" right exactly 2" high @ 100 yrds so 6 clicks to the left with the VXIII and way I go, PERFECT! for both types of bullet,just as a reference I then did a group of 3 with the AEs 1.5" to the left!! WHAT! so I did a group with the Noslers 1.5" to the left WHAT! WEIRD.

So I let it cool down for 10 mins and then did another group of three and we were on the money again?

My only explanation for this would be that the barrel got hot and was touching the stock, making that move the POI.

Does anyone think Im close to the truth on my theory or am I way off?

Thanks Runas

You could be right on the money but than again it might be something else like temperature differential in the barrel.

Free float the barrel and see what happens. roger

quote:

Does anyone think Im close to the truth on my theory or am I way off?

I'd pick the latter. Do as Roger suggests and you will not likely change this phenonima.

These loads just cause the barrel whip to react differently is all.

It could be that the barrel has been straightened at the factory. As the barrel heats up, it will try to bo back, changing the POI. I have a Sako 7Mag that is just about like yours, except mine shoots about an inch high, when I come back the next week and shoot it after sighting in, it's consistently low. It doesn't really hurt it, as I have been aware of it for 25 years. It would be a different story, were it a prairie dog rifle, I'd rebarrel it.

Thanks for the input guys.Rebarreling it does seem somewhat extreme to me, but thanks for the advice anyway

It would be a rare occassion that I would put as many shots through it in quick succession as what I did so with that in mind I may just leave it alone,I was more than happy with the groups it produced before it happened, the best Ive seen from the rifle EVER!It was just a bit of an unusal thing that Ive never seen before, maybe it has always done it, but I never noticed and put the misses down to operator error.

Lack of sleep from worrying about it would make my shooting worse
Thanks again
Runas

Are you getting exactly the same shooting position and hold every time?
Are you using a bipod? I can shoot a perfect group, stand up, pick up the rifle, set it down again, and find my MPI has changed because I moved. Not the rifle"s fault at all, as it"s hard to exactly duplicate your hold every group.
good shooting

quote:

Originally posted by RUNAS:
...My only explanation for this would be that the barrel got hot and was touching the stock, making that move the POI.

Does anyone think Im close to the truth on my theory or am I way off?...

Hey Runas, You and all the above folks may be correct, but... I'd wager on the Barrel Harmonics being different with the other Bullets and Loads.

It is rare to find a rifle that will shoot different manufactures Bullets to the exact same Point-of-Impact. Especially in the smaller Bores.

Runas, maybe you should just enjoy your rifle and make sure it"s zeroed with whatever bullet you need for the job that day.
I use my .243 for most of my shooting, so right now it"s zeroed with 58 gr Vmax for foxes. If I want to shoot a deer, I give it 5 clicks of elevation and load a 100 gr soft point. It"s not a big deal, so long as I know what it"s set for at any one time. Enjoy your rifle and good shooting.

Thanks Hot core and Brass Thief for yor input.
I did get up to goand get some more bullets and that is when it did go all screwy, I was shooting off a bench with bags either end,but I hear what ya saying.

Hot core, I believe also what your saying too, it is a wierd science this shooting.

Before I touch anything on this rifle,what Im going to do is go out and shoot more paper, I will do groups of 5 with all 3 types of ammo, and see how it performs.

I will let ya know how I get on
Regards Runas