You can use a Contract form that requires the buyer to defend and hold you harmless for any damages arising out of the making of the gun. You have to have, or at least separate consideration being given for this agreement( OFFER, ACCEPTANCE, & CONSIDERATION are the 3 necessary elements of most contracts), and it should therefor be drafted by you attorney, so that the buyer protects you from claims by his family, heirs, others for whom he is responsible to support, and his estate as well as from him. You want him to pay your legal fees, as well as other costs of your defense, AS THEY ARE INCURRED,if you have to defend any claim arising from him, or through him. If your attorney is not familiar with this, send me a PT.
The potential liability for you arising out of a gun you build to shoot Black Powder is minimal. However, you might have to incur costs to have the blown-up gun tested to prove that someone loaded Smokeless powder in the barrel instead of BP.
Savage Firearms stopped making their "Modern" bolt action, Smokeless Powder MLER BECAUSE they failed to recognize that some shooters don't pay attention and fail to push the bullet all the way down onto the powder, creating a bore obstruction. The barrel then ruptures, and the shooter is injured. Surprised???
How many new BP shooters have you seen "short-start" a PRB in their barrels, and begin to prime the gun to shoot before someone stops them? As my club's lawyer, I used to stand at the firing line and loading benches and watch how New shooters to the club loaded their guns, and watch to see if they had marked their ramrods( range rods) to indicate that the PRB was all the way down on the powder charge. If not, I would politely talk to them about this safe practice. I stopped more than one guy who had short started his PRB in the barrel, and was going to fire the gun. We taught our Range officers to keep an eye on the new guys to prevent them from ruining their guns, and/or hurting themselves as well as others. One a new shooter demonstrated an awareness of safe loading procedures, and showed he followed them, we turned our attention to other matters. :wink: :thumbsup: