Help needed for M96 Swedish Mauser re-loads

[targetshooter]

Hello, I’ve been shooting my M96 Swedish Mauser (6.5x55) quite accurately for the past year using my developed home loads in which I’m trying to replicate the original rounds. I’m using 44.0grains of Vihtavuori N165 powder and 160grain round nose bullets from B.E.S., which are similar to the Hornady 160grain RN bullets which are no longer available and have an average muzzle velocity of 2445.6 ft/sec. the bore is in excellent condition and I regularly managed to hit the bull at 600yds at Bisley until I deep cleaned the barrel.
I was cleaning the barrel with Bore Tech Eliminator, and decided to try Bore Tech C4 Carbon Remover as the slow burning powder tends to be quite ‘sooty’. My test started with using Eliminator until clean and then cleaned again using Carbon Remover; I was amazed on just how much extra powder residue appeared on the patches.
This is where my problems started; during my next session on the 600yd range I could not hit the target at all and it was estimated that I was about 3foot or more low and over 3foot to the right and I cannot adjust to this with the sights as they are standard ‘battle sights’ calibrated for the original 160 grain bullets and is out of range of their adjustment.
Can anyone suggest what’s going on and how to remedy it, I’m a bit concerned about increase the powder charge and increasing the muzzle velocity on such a rifle as no reloading data seems to be available.

[ovenpaa]

I have seen similar problems with a few older military rifles that have been cleaned enthusiastically and my view is you need to get a few more rounds down it to season the barrel and restore some of the fouling to bring it back to a shootable standard. Typically 30 to 100 rounds and you should see an improvement.

I did exactly the same thing with a No1 Mk3* SMLE a few years ago and these days my 22-250 will have a hissy fit if I copper strip it and take at least 30 rounds to get it back on track :)

[dodgyrog]

Use cast boolits and all your troubles will fade away! Lol

[dromia]

Time enough to clean a barrel when it stops working, over cleaning firearms causes more problems than any other single cause.

[targetshooter]

Thanks for the quick replies gents, I'll spend sometime at the range to re-foul the barrel while shooting them through a chrono hopefully it won't upset the markers or the NRA RCO too much. It had been suggested that now that the lands are clean the bullet is allowed to expand further and thereby increasing friction lowering muzzle velocity and increasing spin shear, is that possible; I guess I'll find that out with the chrono.
If over cleaning is the problem has anyone got suggestions on how to clean the barrel without encountering the problem that I have.

[dromia]

A pass through with a damp Ed's red patch followed with a dry patch and then another damp one and the barrel left at that Is all my guns get, just remember to dry patch afore shooting. When that god awful copper fouling starts degrading accuracy then it is time to get the ammonia out and clean back and start the fouling cycle again.

This jacketed nonsense is one of the many reasons why I use cast bullets which never foul when properly made, jacketed bullets always copper foul, proper lead bullets never lead foul.

[targetshooter]

A pass through with a damp Ed's red patch followed with a dry patch and then another damp one and the barrel left at that Is all my guns get, just remember to dry patch afore shooting. When that god awful copper fouling starts degrading accuracy then it is time to get the ammonia out and clean back and start the fouling cycle again.

This jacketed nonsense is one of the many reasons why I use cast bullets which never foul when properly made, jacketed bullets always copper foul, proper lead bullets never lead foul.

Thanks for the advise on cleaning I'll be using that system from now on. I'll also look into cast bullets but not to sure where I can get a mold from.