Playing as in experimenting with various calibre guns and bullets can be very interesting. A 60" .45 I had would shoot the 200gr. R.E.A.L. bullets into 2" or a bit less at 50 yards off a bench using 75gr. 2F. I lubed them with Lyman's BP Gold, which I find shoots the same as SPG and 60:40 Beeswax/Vaseline. I shot 2, 5-shot groups then loaded up a patched round ball- no wiping was necessary with the bullets nor loading the round ball afterwards. I was using Hoppe's #9 Plus that day.
As for me the .45 was not a hunting rifle, but a flint 'trail walk' rifle, I went back to shooting nothing but round balls. I would not trust a .40 round ball to do the job on a big Mule Deer or big Whitetail Deer's front leg. ribs yes - but if the shot involves having to shoot the leg due to stance and underbrush - I'd not take the chance. A .495" ball or (much) larger would be my choice. I know for a fact that my .69 can hit a bunch of red willow and still strike centre at 100 yards with "enough" to floor a moose. Much depends on what you are hunting in. For me, a .40 is a round ball gun, or if fast twist, a picket gun for target shooting.
I think you meant the linen was .005" thick, Eric. As a patch on a picket bullet, it probably would be fine. I don't know of any commercial .40 cal. (.38/40) moulds that would work as a picket bullet very well. I would think the 135gr. might be best, though - higher speed and better accuracy in the 48" twist, but much depends on it's actual design & length of bearing surface. A starter that "just" fits the bore, land to land AND fits the bullet's nose shape will give more accurate, STRAIGHT BULLET loading, as if using a bullet starter as in the 1840's through to today, for picket bullet matches. The special starter is necessary to get straight line seating of the bullet into the muzzle.
If the bullets are grooved lubricated, mechanically fitted or only .001" larger than the bore, then a starter and rod tip that fit the bullet's nose might be all that is necessary.
For mechanically fitted bullets, I used a piece of barrel, making a die out of it. Pressing almost full sized bullets through this die using an arbor press gave me lubed bullets with the rifling impressed into them. I carried them in individual 'pockets' from a Flambeau ctg. loading tray so they'd not be damaged. I could then load powder, then pull out a bullet, orient it into the rifling and then push it down to the powder. With it's aperture sights, I was able to shoot MOA to MOa 1/2 at 100 yards with this system. The barrel was a .50 Bauska with 38" twist.
This system is something to consider if you have a 'like' barrel.