Went shooting today! Working up a load for my .243 in a Savage 12FV. Caldwell "the rock" support on the forearm and sandbagged at the rear. Very comfortable shooting. I'm using Speer 70gr TNT and Varget powder. Here's the problem. Shooting was going well until around 75 rounds downrange. Then, like a switch was thrown, nothing would hit the paper anymore. The next 10 rounds missed. I spent an hour cleaning the barrell with patches, solvents and brushes. To be honest the barrell just never seems to come clean. Even after all that cleaning, the patch kept coming out blue (after solvent) and blue-black (after the brush). The next 20 rounds were OK and then it happened again. Cleaned again for 1/2 hour and kept running into the same problem until I finally had to get going for home.
I'm going Prairie Doggin' in June and I don't want to spend my shootin' time cleaning the rifle like this. Who can explain to me what is happening? Last year I remember going through 100 rounds of different ammo before a "brief field cleaning," proceeding with another 100 rounds and not having the problem.
Is my barrell just piggy dirty using Varget? Is the Speer TNT a softer copper than the Hornady 75gr V-Max's I used last year? Can you see copper buildup in the barrel?
Wha tis the best cleaning method and how long should it take to clean a barrel? What solvents am I supposed to be using that work the best (and fastest)?
Thank you in advance for all your help. You may have guessed but I'm pretty new at all this.

Ross

PS- I found 39.2 gr Varget and the Speer bullet was giving me 0.8 inch groups at 100 yards. This was the smallest I could discover with all the difficulties listed above. Should I now move with this and start experimenting with bullet seating depth? Change primer to see if better groups? How do I get these groups tighter without burning through a barrell to discover it? There are so many different variables that can change. This could take months! Thanks.

Take the time to clean it down to bare metal. I suggest wipe-out bore foam for 24hrs. then a light lapping or brushing with a patch around a brush with rem bore cleaner. You should see a difference, but remember, 75rnds is quite a bit with no cleaning anyway.

JustC is just right. A pro shooter I know had the same problem you describe of sudden inaccuracy.
Your best bet is to clean more often in the field and don't let it get that bad.
JL

I've shot a truck load of TNTs in the .243 and .224 calibers and never seen amything like that.

I suggest you switch to Hornady's V-Max and see if it continues. If it does you might suspect the barrel.

Savages are usually known for having good barrels. I never had any fouling problems with mine. U may want to run some JB bore paste thru it. If that doesnt do the trick..try some flitz metal polish. Just be careful not to let the brush/patch get to the crown because you can wash it out. But either of the 2 will smooth that bore up nicely.

You might consider the Tubbs Final Finish bullets. They are supposed to help reduce fouling by "lapping" the barrel

lapping the barrel by hand is far less intrusive than fire-lapping. Lapping at 55,000+ psi should be done only on barrels that foul BADLY in relatively few rounds. Use a non-embedding compound (ring lapping compound) and a patch around a brush. If you fire lapp too far, the barrel will lose velocity and suffer at longer ranges. MHO,..YMMV