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Benjamin 31X model history 1950-58  

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Garvin
(@garvin)
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Joined: 3 years ago
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24th June 2020 18:40  

Benjamin 31X model history 1950-58 

With thanks to Steven. First posted on the American Vintage Airguns forum.

 

Below is the most recent layout of years 1950-1958 only. Revised to reflect new data.
The underlined parts show changes specific to that year. This chronology is a combination of gathered information along with some guesswork, but have pointed out some of the facts that led to the rationale behind the thought.
 
-1950-
Intro- The ’50 data is pretty solid and should serve as a corner post for the years following.
Model 310__ Two piece hollow(flow thru) bolt probe, New flat top rubber Hy-car pump seal used, screws securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Rear V sights adjustable for windage only, button style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube. Air intake hole stamped "Air Hole Do Not Oil"
Models 312, 317__ Two piece solid end bolt probe, New flat top rubber Hy-car pump seal used, screws securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Rear V sights adjustable for windage only, button style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube. Air intake hole stamped "Air Hole Do Not Oil"
Facts__
1. Photo examples of boxed rifle with flat-top Hy-car piston seal along with paperwork dated 7-1950. (Thanks to Marty)
2. First mention of “improved with Hy-car piston” in the 1950 Benjamin Catalog. Earlier Catalogs do not.

-1951-
Intro- There exist early grooved pump handle rifles with one-piece bolts (1951) that fit the description below. For the sake of keeping this chronology uncluttered, we will assume Smooth pump handle model production began in 1952 for now.  However, it is not proof that the smoothies did not begin production sometime in ’51.
Model 310, 312, 317__ One piece hollow(flow thru) bolt probe,  Flat top rubber Hy-car pump seal, screws securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Rear V sights adjustable for windage only, button style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube. Air intake hole stamped "Air Hole Do Not Oil"
Facts__
1. The 1958 parts schematic states one-piece flow thru bolt was used since 1951.
2. Photo examples of grooved pump handle rifles held with screws and one-piece bolts.
 
-1952-
Intro- The rifles that have smooth handles with pins must have a start production date. It is placed here because they all have early cast rear sights instead of the stamped steel which came on the scene sometime in 1953. The early production (1952) model 250 pistol also has a solid cast rear sight. These early pistols are not stamped with caliber. Early smoothies also have no caliber stamp on receiver. Later ones have the caliber stamp. The caliber stamp is also found on all the stamped steel rear sight rifles with grooved handles, which are described later.
Model 310, 312, 317__ One piece hollow(flow thru) bolt probe, Flat top rubber Hy-car pump seal, Now has smooth pump handle, pins now secure pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Rear V sights adjustable for windage only, button style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Air intake hole stamped "Air Hole Do Not Oil"
Facts__
1. So far, there are no known rifle examples with grooved pump handles held with pins, cast rear sights adjustable for windage only and also having one-piece bolts.
2. Photo examples with smooth pump handles held with pins and also have no Caliber stamp (1952-'53).
3. Own an early 1952 model 250 pistol, with cast rear sight, that also has no caliber stamp.
 
-1953-
Intro- Like mentioned above, the later production smoothies have the caliber stamped on receiver. If we look at the Pistol models 257 and 252, it should be noted that some have no caliber stamp and some do have a caliber stamp. Both were introduced sometime in 1953, so it is logical to assume the caliber stamp on the rifles was introduced sometime around mid-1953.
Model 310, 312, 317__ One piece hollow(flow thru) bolt probe, Flat top rubber Hy-car pump seal, smooth pump handle, pins secure pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Rear V sights adjustable for windage only, button style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube. Caliber stamp on right side of receiver, Mid 1953 have Caliber stamp added to right side of receiver, Air intake hole stamped "Air Hole Do Not Oil"
Facts__
1. Photo examples with smooth pump handles held with pins and also have no Caliber stamp (1952-53).
2. Own examples of smooth pump handle rifles with flat-top pump seals and the Caliber stamped on right side of receiver (mid 1953).
3. Own a Model 257 with no caliber stamp (Early 1953??).
4. Own a Model 252 which has a caliber stamp (Mid 1953??)
5. These pistols were only produced for a couple years. (Model 257(1953- ’55), Model 252(1953- ’54)
6. Known boxed smooth pump handle rifle with documents dated 7-1953. (Thanks to LarryH)
 
-Late 1953-
Intro- The Model 250 pistols have stamped steel rear sights by this time. This may also be the same time frame the grooved pump handles were re-introduced. They added the stamped steel rear sights to the rifles as well along with serial numbers. Grooved pump handle rifles at this point in time still sported the button style safeties like found on the smoothies manufactured earlier in the year.
Model 310, 312, 317__ One piece hollow(flow thru) bolt probe, Flat top rubber Hy-car pump seal, Changed back to grooved pump handles, pins secure pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, New stamped steel rear sights adjustable for both windage and elevation, button style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial numbers added on left side of receiver, Air intake hole stamped "Air Hole Do Not Oil"
Facts__
1. All the stamped steel rear sight rifle models have grooved pump handles, H prefix serial numbers stamped on left rear of receiver and are all stamped with Caliber on right side of receiver.
2. Model 252 and 257 pistols came out sometime in 1953 and they have the stamped steel rear sights. If early versions had cast rear sights is unknown to me at the moment.
3. Own examples with grooved pump handles, button style safety and stamped “Air Hole Do Not Oil” at air intake hole.
 
 -1954- 
Intro- Not sure if the change to tang style safety happened simultaneously to the elimination of the oil hole warning stamp, but have a rifle with both characteristics.
Model 310, 312, 317__ One piece hollow(flow thru) bolt probe, Flat top rubber Hy-car pump seal, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, Models now have tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Air intake hole no longer stamped "Air Hole Do Not Oil"
Facts__ 1. Own example of stamped steel rear sight model with tang safety that is not stamped with warning at air intake hole.
 
-1955- No Changes
Model 310, 312, 317__ One piece hollow(flow thru) bolt probe, Flat top rubber Hy-car pump seal, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver.  Air intake hole not stamped "Air Hole Do Not Oil"

-Mid 1955(06/01)-
Intro- Mic’d several pre 1955 rifles to get average tube and hammer specs. mentioned below. Bolt probe is the only change.
Model 317__ Changed back to one piece solid end one piece bolt probe, Flat top rubber Hy-car pump seal, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Specs of rifles dated between 1939 up to mid-1955 _ (Tube Wall is .030”, Tube I.D. is .811”, Rear cap O.D. is .810”, Hammer Diameter is .802”, Hammer weight is 76.14 grams)
Model 310, 312__ One piece hollow(flow thru) bolt probe, Flat top rubber Hy-car pump seal, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Specs of rifles dated between 1939 up to mid-1955 _ (Tube Wall is .030”, Tube I.D. is .811”, Rear cap O.D. is .810”, Hammer Diameter is .802”, Hammer weight is 76.14 grams)
Facts__
1. The 1958 parts schematic states one-piece solid end bolt was used since 6-01-1951.
 
 -1956-
Intro- Mic’d several post 1956 rifles up to 1972 to get average tube and hammer specs. mentioned below. Tube, hammer and pump cup changes.
Model 317__ One piece solid end one piece bolt probe, Improved rubber Hy-car pump cup with thru hole now used(because I.D. of tube is now smaller), pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness changed to .050”. Tube I.D. is now .773”, Rear cap O.D. is now .767”, Hammer Diameter is now .764”, Hammer weight is now 64.9 grams
Model 310, 312__ One piece hollow(flow thru) bolt probe, Improved rubber Hy-car pump cup with thru hole now used(because I.D. of tube is now smaller), pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness changed to .050”. Tube I.D. is now .773”, Rear cap O.D. is now .767”, Hammer Diameter is now .764”, Hammer weight is now 64.9 grams
Facts__
1. The 06/1958 parts list shows a Breech Cap change from part# 301 to 3101 which occurred 1-01-1956. There was also a Hammer change from part# 392 to 3192 at the exact same time. New tube wall thickness and hammer diameter shown in description above reflect this change.
2. It is logical that the change from Hy-car flat-top piston seals (part 3151) to the later cupped versions (part 3152) happened at this point in time to compensate for the smaller ID of tube.... 1-01-1956
 
-1957- No Changes
Model 317__ One piece solid end one piece bolt probe, Rubber Hy-car pump cup with thru hole, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness is .050”. Tube I.D. is .773”, Rear cap O.D. is .767” to reflect, Hammer Diameter is .764”, Hammer weight is 64.9 grams
Model 310, 312__ One piece hollow(flow thru) bolt probe, Rubber Hy-car pump cup with thru hole, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness is .050”. Tube I.D. is .773”, Rear cap O.D. is .767” to reflect, Hammer Diameter is .764”, Hammer weight is 64.9 grams
 
-1958- No Changes
Model 317__ One piece solid end one piece bolt probe, Rubber Hy-car pump cup with thru hole, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness is .050”. Tube I.D. is .773”, Rear cap O.D. is .767” to reflect, Hammer Diameter is .764”, Hammer weight is 64.9 grams
Model 310, 312__ One piece hollow(flow thru) bolt probe, Rubber Hy-car pump cup with thru hole, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Stamped steel rear sights adjustable for both windage and elevation, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness is .050”. Tube I.D. is .773”, Rear cap O.D. is .767” to reflect, Hammer Diameter is .764”, Hammer weight is 64.9 grams
Facts__
1. Photos of rifle H91686 (dated up to mid-1958 according to the dating chart on the Crosman website) has “stamped steel” rear sight.
 
 -Mid 1958- 
Intro- Updates to Front and rear sights
Model 317__ One piece solid end one piece bolt probe, Rubber Hy-car pump cup with thru hole, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Early models still have stamped steel rear sights adjustable for both windage and elevation, Mid ’58 models have new Bar-V rear sight and front sights moved forward, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness is .050”. Tube I.D. is .773”, Rear cap O.D. is .767” to reflect, Hammer Diameter is .764”, Hammer weight is 64.9 grams
Model 310, 312__ One piece hollow(flow thru) bolt probe, Rubber Hy-car pump cup with thru hole, pins securing pump handle, screws in muzzle plug, lever hinge pin lock screw on right side, Early models still have stamped steel rear sights adjustable for both windage and elevation, Mid ’58 models have new Bar-V rear sight and front sights moved forward, tang style safety, "BENJAMIN FRANKLIN" “MADE IN U.S.A.” stamped on left rear of tube, Caliber stamp on right side of receiver, Serial number on left side of receiver. Tube wall thickness is .050”. Tube I.D. is .773”, Rear cap O.D. is .767” to reflect, Hammer Diameter is .764”, Hammer weight is 64.9 grams
Facts__
1. Photos of rifle H93818 (dated mid-1958 according to the dating chart on the Crosman website) It has a Bar-V rear sight and front sight mounted more forward than previous rifles.

Proof read this quickly so it may contain mistypes.   As always......Subject To Change as more data is collected.
Steven


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