I know that MBS is a decent company, but pre inlet stocks aren't as accurate as one may think. Your barrel is inlet, but you may have to back it up a tad to avoid having to notch the breach plug when drilling for the touch hole. Drop a ram rod blank down the barrel and measure where the plug face is located. Does this match up with the centre of the pan on the lock inlet ?? Is it too high or low on the barrel ?? These are just a few of the things that can be off on a pre carve. A really good instruction video is offered for sale by Chambers, re Building from a kit. If you've not done this before it and a good book on building will be well worth the $