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Discussion of Benjamin models C and D

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Discussion of Benjamin models C and D 

This information is taken from the American Vintage Airguns forum.

With thanks to Larry H and D T Fletcher (Decd).


Larry asked:

If we call the specimen on the left (with the illegible end cap) the later variation of the Benjamin Model C, what do we call the mythological specimen on the right?

Dean Fletcher replied:

The most notable thing about your gun is that the "Model D" marking is much heavier than the rest of the stamping and doesn't show the same level of wear as the rest of the cap shows. It also doesn't match the style of stamping seen on the "E" model. It's notable that the area where the E stamping is normally be seen has been heavily worn to the point that anything originally there is now gone. I think there is the possibility that this stamping was not done at the factory.

What does the internal valve configuration look like? If it is the same as the "E" then I would suspect fake markings. If it is different and matches one of the early patent configurations (there are two) that have never been seen before then that would make it something very special.

Here's a closeup of the model "E" end cap.

It's notable that the early Benjamin models are covered by patents.

The Benjamin Single Valve is covered by 822,645
The model C is covered by 1,073,454

The model E and F are covered by 1,233,944 The E is the patent pending version, the F is the patented version with both guns having the same valve configuration.

There are also two patents 1,073,455 and 1,079,908 which do not have exact examples seen in any of the production guns. In other words, the valve configurations seen in these two patents have never been seen. If a model D actually does exist then it would seem likely that it would be covered by one of these patents. The most likely patent to cover a model D would be 1,079,908, since this patent date is seen on the model F end cap.

So, if a Benjamin can be found that has the same valve configuration seen in patent 1,079, 908 then that would be strong evidence for a model D. The configuration of this patent includes a exhaust valve seat that looks much the same as the model E, F guns. However, the check valve is very different and distinctive. Here's a cropped view of that patent.


Larry H said:

I bought this Benjamin Model D 31 years ago from an old man at a flea market for $15. I can't believe I was so gullible to fall for such an obvious forgery...I guess I was just too excited at the discovery of what I thought was a rare Benjamin model I'd never seen before. (And I had no idea that he was such a Benjamin scholar that he would know and capitalize on the rarity of the piece he cleverly faked). I hope he used his ill-gotten windfall profits to buy himself some new teeth, because even with him and his mangy old dog, they did not have a full set of teeth between them!

Okay...enough of this nonsense. The Benjamin Model C used a single ball valve that acted as the check valve and exhaust (firing) valve. This ball was positioned at the upper end of the hollow "stamen" tube (which flexes downward against it's natural spring action) and below the exhaust port. (#1,073,454).

The Model D uses the same hollow stamen tube as the C, but now the check valve and firing valve are shaped more like the valve disks seen on the E/F guns and are placed back-to-back on top of the hollow stamen. This Model D valving is VERY DIFFERENT than the E/F guns, and much more closely related to the Model C. Neither the Model C nor the Model D can be further disassembled than what is shown without de-soldering the hollow stamen from the receiver.

Of course, all of us modern airgunners realize the fallacy of having a long transfer port before the check valve as it holds too much residual air before the check valve can store it from the end of the pump stroke. Hence, the development of the E/F valve which places the check valve directly against the input wall of the valve chamber to eliminate that design flaw.

I do not have a hard time imagining that Benjamin would reuse old end caps from the Model C and restamp them with "Model D" to differentiate the new improved Model D. Hopefully, the attached few photos will make the valve differences more obvious between the "C" and "D". The trigger spring on the D (and the cork plug instead of rubber) may be a later replacement...I don't know. Certainly, this specimen marked "Model D" is in NO WAY a reworked later E/F airgun!


Dean replied:

Well, these pictures certainly tell the story. Externally, the model D is the same as the model E (the external exhaust valve seat assembly and the covered trigger.) Then, internally, the model D is like the model C but with model E style flat valves.

Why were these changes made? The 1,233,944 Wissler patent is all about improvement in reliability of the flat valves verses the ball valves and also ease of user repair. Doubtful that Wissler would much care about minor performance improvements. What he cared about was the initial reliability of the gun and how easy it was for the user to repair. Business stuff not performance stuff.

The most interesting part (to me) is that this configuration is not covered by any patent. So, since the model D is not covered by any patent then the chances are that the other model designations are not a reference to any particular patent either.

A critical issue for Benjamin is what repair parts does the user need. When these guns were produced, there was no such thing as an authorized repair shop. The expectation was that the user would repair the gun with parts supplied by the company. The customer, in need of performing repairs, would write a letter to Benjamin requesting the needed parts. At Benjamin, any change in the parts list resulted in a model change.

So, this also means that there has to be some parts related differences between the model E and F. And, taking a close look at the model E and F repair sheets there certainly are some small differences in the parts. Won't go into details here but the idea the model E is ONLY the patent pending version of the model F is.... non operative. There are a number of distinct differences.

It all makes sense now.

Yes, the model D exists and you have one of the only known examples. The model D is true transition model from the C to E. The specific configuration of the Model D is not covered by any known patent. The Benjamin model letter is a direct reference to changes in the repair part list.

The models A and B? Well, considering all of the above, I would think that when Wissler designated the model C he was thinking that there were two other models that he had already produced or had to supply service parts for. One of these has to be the non-designated model with the exposed trigger assembly. There is also the Single Valve model produced by the W.R. Benjamin Co. in Granite City. The models A and B.

Thanks, Larry!