Thanks. Yes, that's exactly what I did before the picture with the screw contraption was taken. Having the reamers I could experiment and recut easily if I wasn't happy.

One thing to mention to others wanting to replicate the funnel shaped crown. I made a bunch of half by half inch squares with a p600 grit sandpaper. I used those squares wrapped around my finger (counting same number of sanding moves every 30 deg of barrel rotation, swapping for new square after each 30 degree step to ensure same sandpaper state). This counting may have been a bit of an overkill for a short range rifle. I'll explain why later.

In the end I reverted to a much shorter 45 degree crown for mostly esthetic reasons, but I kept a slightly larger ball/patch combo.

I was loading a 58 cal howdah right next to my Kodiak with the same thick patch/ball combo. The Howdah had my short 45 degree crown polished with a slightly oversized lead round ball and polishing paste (the ball confirms to the muzzle shape somewhat so it removes all sharp angles). The Howdah was perhaps very slightly harder to start, but I can't be certain the barrels are not very slightly smaller. At the time I realised I much prefer the angled look of a "machine cut crown" (despite it being really cut by hand reamers).

So that's why I went back to the 45 degrees with the Kodiak. I didn't notice any difference in loading patched round ball (I did notice loading REALs and Minnie's was easier with the funnel.) or on target afterwards between the two. That is not to say there isn't a difference between a manufacturer cut crown and Darryl's. Both crowns tested were cut by myself. That's what I'm comparing here.

I encourage others to experiment with regards to the crowns of their rifles and to find what they like best. Worst case scenario is it will need recrowning.

One more thing I did is also polishing the whole lengths of both bores slightly with 0000 steel wool wrapped around a brass ramrod end. The whole ramrod was spinned at around 300 rpm by a cordless drill and a plastic muzzle protector was used. Again this was done for esthetic reasons. I didn't notice any difference on the target after.

Regarding possible precision of a finger sanded crown I think it is sufficient for patched round ball rifles at up to 75m at least. One of experiments I did with those barrels was checking if the point of impact can be moved by (lightly) opening the crown more on a side one wants to move poi against. The amount of material removed was no more than 1~2 thou with my sandpaper squares right at the range. Interestingly I saw no difference in poi with a patched round ball at the distance of 50m when I deliberately made the crown egg shaped by 1~2 thou. No doubt use of conicals would be a different story. Also no doubt removing more material would have some effect, but I was only interested if poi can be pushed by very light manual sanding. This shows that sanding a crown less than ideally by 1~2 thou is not going to break a hunting prb shooting rifle. This experiment was done when I was committed to recutting the crown anyway. It is round to a couple tenths now.

Finally, about patch thicknesses. Where I am located there are no cloth shops left where one can go with a micrometer and check lots of fabrics to find one to buy unfortunately.

The only way to get cloth is to order online by specifying the type (it is usually called plain cotton, heavy variants are also called denim in some shops) and the weight in grams per square meter. I managed to get all weights available between 120 and 300 grams before.(120g compresses to 7 thou, 300 to slightly below 20 thou, other useful weights for patching are 230,280 and 180. 120 is really only good for cleaning with as it is not only thinner, but also less dense IMO).