There is an issue with the Remington ultimate muzzleloader having headspace problems. Although the overall case length is important it is more important to have the correct case head thickness. It is critical that case head fits the nipple tight for a good seal, and the case head thickness in brass varies greatly.
Example only...…….. if a case with a head thickness of say .200" creates the perfect seal between the case and the nipple, what happens when the next case is .180"? The overall length of the brass case means nothing. Only the thickness of the brass head or web matters. Then some of the cases are known to have the inside flash hole up to .010" off center.
If you were to find the thinnest head on a piece of brass, you can have your head space set to that specific piece of brass. This becomes your pilot. However...…… any other brass with a thicker head will not allow you to close the bolt. So here's where all the work comes in.... you have to trim every brass case to the exact same length. Once the cases are trimmed, including your pilot case, you have to use a reamer for the inside of the case on the primer flash hole. You set the depth using the depth of the pilot case. Then ……. every case...… has to be reamed by hand.
Then you have Remington, who even though they know about the brass and head space issues, have yet to step up and fix the issues. With everyone wanting to shoot Blackhorn 209 (BH209), they started shooting it in the RUM and gas cut to many breech plug nipples, so, Remington stopped warranting breech plugs that were known to have used BH209.
This headspace issue is why Remington doesn't recommend the use of Blackhorn209, with bad headspace leakage in the form of blowby and gas cutting occurs.
Keep a very good eye on your spent cases. The inside of each piece of brass requires a visual inspection each time its fired. If its completely clean inside, then that's a good thing. If its dirty inside, then its leaking gas and shouldn't be used again.
here's a pic of what to look for
