The gun was at the April Tulsa show and the owner claims the letter is proof the gun was Parker's first hammerless gun. It has a side lever to open if I remember correctly but I really doubt Parker asked Lefever to convert a hammer gun hammerless for them. It is certainly interesting but my first thought was "Why would anyone ruin a nice hammer gun this way?"

I think - could be wrong - you still open the gun with the lifter underneath.

Unusual patent mark on the lock, "pat 20 1880". Generally, patent marks are done as month day and year like the one pictured on the bottom of this guns frame.

Looks like the locks of a typical side-cocker Lefever replacing the Parker Bros. hammer locks.

I think these bolsters look like they are engraved with designs mean to invoke lightning bolts or electricity. Is that correct?

If so, it's very interesting (to me) as this gun would have been built right around the time electricity was becoming part of the world as we know it. The 1870's and 1880's saw a tremendous rise in the knowledge base related to electricity, and of course it was all manifested in products such as light bulbs, motors, and all sorts of other devices.

I'm guessing this was pretty avant garde engraving for the time.

Lightening bolts engraved at or around the plunger heads was a relatively common theme especially on grade 3 and higher Parkers or their equivalent dollar grade.






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I would guess that Lefever used this gun to experiment/test his ideas on the side cocker patent but for the life of me, can not figure out why he would use a Parker. He was building his own guns during this time period. I question the statement that Lefever only built 750 sidecockers as about 20 years ago I purchased 2 side cockers at Frank Lefever's gun shop. They were consecutivley numbered 10 gauges, serialed 4999 and 5000.

Dan Lefever was one of America's most accomplished firearms designer, perhaps second only to Sam Colt. He was a terrible businessman, evidenced by the number of failed Lefever partnerships.
There is no doubt we have a different perspective than they had back 120+ years ago, but it doesn't seem like the pride of the Parker's would have them offering up one of their guns for someone else to make claims of advancements in design. I would only be guessing, but it might seem more likely that the gun was supplied by someone else; perhaps a customer, who wanted it converted. I don't think anyone is claiming that the subject gun at Morphy's was a prototype.
In studying the pictures on the Morphy website, it appears that the Parker frame is unaltered, and perhaps can be converted back to a hammer gun simply by removing Lefever's lock, and re-installing hammer-gun firing pins. I think it is a beautiful piece of workmanship, and it seems to me the side cocking lever makes the gun that much quicker to reload and fire quickly. I think it's a fabulous opportunity for a collector. High grade Lefevers are perhaps the only American SxS that rivals a Parker of equal grade, for beauty, and design. A friend has an 1875 Nichols & Lefever push button opener that is as nice as any $250 Grade I have ever seen.

John Browning....?

Good point! How could I be so remiss?