No. 3 now mentioned. Make one from a DB shotgun.

1. Buy an original. Muzzle loader, cheaper Breech loader, more. A smooth bore can be cheap. I seriously looked at a smooth bore howdah pistol in Italy. $1000. But too much to get here.
2. But an original rifled Howdah pistol.
3. Modify a side by side shotgun into a smooth bore or rifled Howdah pistol.
4. Buy and modify a Pedersoli as required.

If Marrakai succeeds, we will see it, and be jealous.

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As for what and why DRs are excellent and the best, in particular circumstances, as mentioned numerous times on these forums. DG, big bores, close up, quick follow up shots. Why every PH has one or wants one.