Scout V2 rifling

what size group are you having,  and have you tried wool wads, there is a screw under the for arm stock, it has a set screw holding it in place, this helps the stock to snap on, others here have helped me with this, if you back out the screw slightly, it firms up the fit, and has improved my accuracy with a couple of these guns ( I lock it back down with BLUE 242 loctite)  I use the IMR 4198 and the Pittman bullets, and have used the Parker 275 and they did very well also.... just my thoughts

Thanks for the tip on the stock Sureshot. I did see that in another post so had done that before my last testing.  My groups have gone from occasionally touching to moving 3 to 5 inches.  I did get the wool wads from Parker but have only tried one.  I did use Purple Vibra-tite on the scope base attached to the gun and that seems secure.  I just now noticed however that the clamps have loosened slightly where the rings attach to the base.  I will try to shoot more groups in the next few days. 

Sharp rifling is actually a good thing, and shouldn’t be the cause of poor accuracy. I wouldn’t lap it to remove the sharp edges. If resistance is uniform, at most I would hit it with some JB paste.
The bases that come on these rifles are not the best quality. I replaced mine with machined picatinny rails from Hankins, and bedded them with epoxy to help eliminate any issues. These things have a tendency to be rough on optics due to the way the bases sit right over the charge and the recoil they produce.
Definitely adjust the forearm if needed. I had one that started vertical stringing. The forearm was loose and after adjusting the vertical stringing was cured.

jeapeater, I have wondered this myself about the sharp rifling burrs. It might even be a benefit as it might get a good grip in the bullet to get it spinning quickly? I've not personally seen rifling with sharp raised corners before and I had seen comments on recent posts about some of the newest Scouts having accuracy issues so it got me wondering. As for the base, I did lock tire the screws but I'm sure you are correct that it isn't the best base.

Just an FYI on the loads I've tried: At first I was using 57 grains by weight of IMR 4198 and 250 grain Hornady FTX bullets sized to push down the bore with light pressure, then tried the 275 grain Parker BE's when they arrived. They push through the barrel with moderate pressure without sizing. I then upped the charge to 60 grains of IMR 4198 using the Parkers hoping that would help Obturate the bullets if that was an issue. I'm going to remount the scope (Vortex Diamondback 4-12x40) from the bottom up and shoot it again in a few days when the weather here in Wisconsin clears up. If that doesn't work I will change scopes and try again.  I will let you know what I find out. In the meantime, any suggestions are appreciated. 

Like others have said the sharp edged lands of the rifling is a good thing especially for a muzzleloader. I think unless you have a crown problem it’s a matter of working up a load that the gun likes. Btw I see the sharp edged land marks on your bullet. If you can get your hands on some imr 4759 @ 38gr with that parker I bet you would get same hole groups or close to it @100 yd.

What kind of scope do you have and did you try it on another rifle that it worked well on ? The eastern maine wool wads work well I buy them here in milo maine. I use the ones made for a 50 cal in my 45. It’s also possible that you need to touch up the barrel crown.

Here is what I would do if it was my gun.

1 - Check the set screw on the forearm and make sure it locks up tight with zero play. If you haven’t used blue Loctite on the set screw, now’s the time.

2 - Remove the stock CVA pic rail and buy a Hanks Precision pic rail.

3 - Buy a set of Hank’s Precision 4 or 6 bolt scope rings. Mount the rear scope ring in the last slot,, it will put the over top of the pic rail bolts. Mount the front ring as close to the turret body without touching it, this will get you as close to the front bolts as possible.

4 - I would cut off any unused pic rail that forward of the front scope ring and JB weld it down to the barrel. If your not using it, cut it off because of barrel flex.

5 - Install your rings and make sure you push them forward before your torque them down to the rail. Use blue Loctite (purple is low strength). Install your scope and torque the top ring cap down with blue Litite.

6 - Buy a scope level.

If you are shooting a PROVEN load out of a CVA break action with large Magnum rifle primers with:
62 grains of 4198 with a 300 grain Pittman
53 grains of 4227 with a 275 grain Pittman
53 grains of 4227 with a 265 grain Fury
65 grains of 4198 with a 265 grain Fury
65 grains of 4198 with a 275 grain Pittman

If it still doesn’t group

7 - Change out the scope with someone else’s scope that on a SML that you know is proven to hold up to recoil.

8 - If you think the crown has a burr, polish it off or cut a new crown. The crown should be sharpe and burr free.

As far as the way your bullet looks, it looks like it should. Your bullet is ride down the rifling and it will have marks on the jacket from the rifling.

Now that your gun is built, head space is correct, leave your telescope gauge and micrometer at home and set your die by how the bullet goes down the barrel. It’s a feel thing. 

Wow, lots of great suggestions here. Thanks guys! It sounds like my raised corner rifling might be common and not a bad thing? That was my biggest concern to start with. I am going to leave that alone and start over after re-mounting the same scope which is a new Vortex Diamondback 4-12x40. If the problem persists and the scope mounting doesn't appear to have moved, I have a new Burris 4.5-14x42 and will swap to that.

One more detail is that I am using CCI #34 large rifle primers. The are the only large rifle primers that I have been able to find. They are slightly thicker skin to prevent bump fires in semi autos and although not specifically magnum primers, the description says they have a magnum charge. They seem to have good reviews even from magnum centerfire guys. Anyone else using these?

So, another thing I have done is ordered another Scout V2 45-70 so I can visually inspect the rifling. I should have it early next week. This one is the camo version and from a different seller so I figured it would be highly unlikely that it was rifled in the same batch so should be a good comparison. If the rifling looks good or if I get my stainless version shooting well I will convert that one too and see how that one does. I did have a hard time finding one of these camo models but the stainless model as well and wonder if the demand is high because of these conversions to smokeless?