Crosman 100 multi-pump pneumatic rifle.
This report covers:
- Model 100
- How I got it
- What is it?
- Description
- Instructions
- Why, BB?
- Summary
This report series should prove fun for many of you readers. It’s about a significant historical air rifle that’s still going strong after almost a century. Crosman’s 100-series air rifles—models 100, 101, 102 and 103. That family of multi-pump pneumatics got their start with the Crosman model of 1924, which was a .22-caliber multi-pump that came to market in—you guessed it—1924!
The model 100 we are looking at is simply the .177 caliber variation of the .22-caliber 101 that got started in 1925. The model 100 is scarce because during the time when it was manufactured, .177 was not a popular caliber in the United States. The larger .22 sold many times as many guns.
Model 100
While the model 101 .22 caliber rifle started production in 1925, it wasn’t until 1940 that Crosman added the .177 caliber model 100 rifle to the line. Throughout the years of this rifle’s run (1940-1950), the Crosman Corporation didn’t appear overly fond of the .177 caliber. They seemed to have offered their airguns in that caliber just to satisfy a growing demand that may have been created when military personnel returned from World War II. Returning soldiers, sailors and airmen had seen the small .177 or 4.5mm caliber in Europe and decided that was what they wanted. But American airgunners who hadn’t been to war would still be wed to the .22 for another 15 years.
Production of the 100 ended in 1950. It’s impossible to know for certain how many were made but I have seen about one hundred Crosman 101s for every model 100 I’ve seen. But since they are identical except for the caliber there may have been some that escaped my notice. Just know that this model is scarce!
How I got it
I first saw this particular rifle on the table behind me at the 2017 Texas Airgun Show. I was more interested in the .22-caliber Crosman 102 repeating multi-pump sitting next to it, but once I read the tag on the trigger guard of this rifle and discovered it was a model 100, my interest increased.
Neither gun sold at the show, so as we closed down I bought them both. The seller was none other than reader Cloud9 whose name is Jeff Cloud. Luckily for me he had resealed the 100. Jeff is a wizard at overhauling multi-pumps and he did my 1978 Sheridan Blue Streak several years ago. It’s still holding and shooting just fine.
What is it?
A 100-series Crosman multi-pump is one of the oldest types of pneumatics made in the US. Only certain models of Benjamins and a couple other very rare types are older.
The rifle is an underlever pump. When it first came out there were very few instructions with it. Both the .22-caliber 101 and the .177-caliber 100 were called the Silent model from around the 1930s to the end of their run. That referred to the quiet discharge sound, compared to a .22 rimfire.
Crosman also used the slogan “Power Without Powder” for much of the production run. The model number crept in much later, probably to help keep the parts organized (the parts peculiar to a specific model like the barrel often have the model number incorporated into the part number).
Description
This is a single shot bolt action multi-pump pneumatic air rifle. My example weighs exactly 5-1/2 pounds. Overall length is 35 inches with a 20-inch barrel, so this is a smaller air rifle. Length of pull on this one is 13-1/5 inches, so it feels on the small side of slim and compact.
The bolt has a half pin (arrow) that pushes against the back of the receiver, pushing the bolt forward and sealing the bolt face.
When the bolt is pushed forward by the half pin shown above, the mating angles of the bolt face and barrel breech seal air tightly!
The rifle I am testing for you is all metal and wood. Some have hard rubber pump handles with a rubber pad under the pump handle to cushion the sound of the handle as it closes against the pump tube. The metal parts are either steel in many cases or cast aluminum like the receiver.
Model 100s almost all have bronze barrels. Crosman started rifling their own barrels around 1948 and bronze was far easier to rifle than steel. It also resists corrosion from the rapidly decompressing air when the gun fires. A few steel barrels are encountered on rifles of the late 1940s, but the norm is bronze. From the factory bronze barrels always came painted; steel barrels were blued.
Instructions
In the beginning Crosman set a maximum pump limit of 6 pumps and they didn’t specify a minimum. As time passed their literature began to say that more than 6 pumps were okay if you really needed the power, but six were still the recommended maximum. I typically stop at 8 strokes when I’m going for power—an upper limit set by Sheridan.
You must cock the gun before starting to pump. If you don’t, all the air will be exhausted on each pump stroke because the heavy spring-loaded striker presses against the firing valve, holding it open when the gun is at rest.
That raises the question of how to leave the gun stored with a pump of air inside — which has been recommended by Crosman since the 1920s! The answer is to pump in one or two pumps (I put in two), then hold the cocking knob and pull the trigger. You can lower the striker slowly this way and the gun will remain sealed, but most owners do one additional thing. They unscrew the cocking knob until all tension is off the firing valve, ensuring the gun will remain sealed. A gun that’s properly sealed will hold air for many months this way.
The cocking knob unscrews to relax tension on the stem of the firing valve.
Why, BB?
Why, in this airgun blog of blogs are we looking at a near-century-old pneumatic? Well, this morning I fired it and after several years it was STILL HOLDING! I believe I recently ranted about how many modern pneumatics do not hold a charge. This antique one does.
Gee—could something be learned from this?
Summary
This will be a normal test of an air rifle. But as we test we’ll also remember that not all great things are being made today.
Tom,
Yay! Back to the classics to relearn the basics. Unscrewing the cocking knob seems to be an invitation for it to get lost though.
RidgeRunner,
Don’t you have one waiting for you to find your roundtuit?
Siraniko
Siraniko,
There are many more threads on that shaft. You learn where to stop and be safe.
BB
If you can manually unscrew the cocking knob, does that mean you can adjust the hammer spring tension for any given number of pumps, thereby fine-tuning velocity?
Roamin,
Theoretically, yes. But I’ve never tried it and I don’t know anyone who has.
BB
Roamin
Now that is a good question. If BB thinks it may adjust hammer spring tension I’m hoping he will test it if it has merit. Who knows, it could give pcp designers something to think about. But I don’t want an under powered pellet stuck in the brass barrel. Plus a multi pump already adjusts velocity by varying the number of pumps.
Deck
I agree about getting a pellet stuck in the barrel is probably a giant pain, because you might have to diassemble the gun to remove the barrel so you would not damage the crown of what is probably a brass barrel.
Here’s my thinking, though: I have several Crosman Mark I and II pistols. The earlier ones had a hammer spring adjustment screw. In testing, I found that as much as a 1/8 turn had a remarkable affect on accuracy. Here’s a pic I have posted before. The same gun would shoot up to 1″ groups at different hammer spring settings.
By extension, if the cocking knob adjusts hammer spring tension, then theoretically, you might be able to tune this gun to shoot a pellet at say 6 pumps very accurately and precisely. A whiteout pen or even a pencil mark could be used to be able to return to the same spot.
Siraniko,
Your rememberer works far better than mine. The truth is I have so many airguns now that I need to get rid of some of them.
Siraniko,
Had Tom used the term Backing Off instead of unscrewing it might have been more descriptive as well as translate better for those that use a translation App.
shootski
“…after several years it was STILL HOLDING!”
BB,
That’s pretty cool! I’m looking forward to this series. 🙂
Praying your New Year is awesome,
dave
dave,
I’m looking forward to it as well! 🙂 And thanks for your prayers.
BB
You’re on my prayer list everyday! 😉
brother dave,
Thank you. I receive that!
BB
BB
I bought my Crosman 100 a few years ago at the North Carolina airgun show near Hickory. The seller showed me how to leave pressure in it just as you described. He said if you unscrew it too far not to worry. Simply screw it back on enough to grab the threads. There is little or no tension involved at that point. He said he leaves 3 pumps of air in the rifle so that is what I do. I shoot it with 4 pumps and there is no sign of air leaking. I think my gun was made in 1947. It is surprisingly accurate and gets exercised at least monthly. The cocking knob is a bit difficult for arthritic hands. I use a rubbery flat pot holder to grasp the knob which makes cocking much easier.
It is one of the last guns I would let get away. Looking forward to more reports on the Crosman 100.
Deck
Deck, how often and how do you oil it to keep the internals healthy?
Roamin
I use several drops of Pellgun near pump lever at entry into compression tube. While there is no felt pad to swab the interior, I squirt some into the small air hole on underside of compression tube also. Any excess gets blown out muzzle when shot. I do this every month or two.
Deck
As Siraniko has pointed out, there is a Crosman 101 here at RRHFWA. I attempted to rebuild it, but failed as I could not find the proper seal for the internal valve. I did order a rebuild kit, but have as of yet to install it. This series will likely get me off my buttocks and get me to finish rebuilding it.
BB, that 100 is in beautiful condition. My 101 is not near as nice. I think mine was built after WW2 and is all steel, with the aluminum receiver of course. The old rear sight of mine had been modified to be a notch sight and the disc and screw are gone.
RR
My rememberer has us getting your 101 and my 100 the same day. You noticed mine and asked if it was a 101. I hope to get to Carolina Airgun show this year.
Deck
Deck,
So do I. I picked mine up locally. This past year there were pumpers everywhere, including some Sheridans.
I really need to dig out my round tuit and get that 101 up and running.
RidgeRunner,
The SEAL you are needing is the one on the valve stem as opposed to the pump head?
https://www.jgairguns.biz/102-and-104-c-78_89_96/crs101017-exhaust-valve-stem-p-9282.html
shootski
shootski,
No, I am needing 105-31, Exhaust Valve Body Gasket. It is a weird size o-ring. I should have one in the rebuild kit I ordered. I just need to find my round tuit again and install the kit to get it up and running. Too many other projects that need doing. Some of the most important ones are related to Mrs. RR’s wishes.
RidgeRunner,
That one is important on a pumper.
Totally understand the PROJECTS :^)
shootski
Thanks for this blog BB!
I wish that Crosman would do a production run of their 101, I’d pay good money for one! The current ones they offer are no where near as good.
The 101 that I got from my father was in rough shape when I got it back in the 60’s. Did my own gunsmithing on it, making new leather piston seals and parts.
As a. 22 caliber multi-pump my 101 was the envy of all my friends with their .177 break barrels. It was the ideal rabbit and squirrel hunting rifle for the urban area where I lived, anything more powerful would attract unwanted attention.
I put many thousands of pellets through the 101 – had a good sized cardboard box full of empty pellet tins from one summer of shooting. The rifle is pretty well worn out and would require replacing most of the parts to get it functioning again. (Guess that that applies to me as well LOL! )
I considered machining new parts for the old rifle… maybe. Have the tools and the materials. More likely I will let it stay retired for nostalgia reasons.
Happy Monday all!
Hank
B.B. and Readership,
“Gee—could something be learned from this?”
O-Rings and synthetic seals are EVIL?
Not really just that the design, material selection, installation, and preventative maintenance need to be near perfection the higher the contained pressure. I doubt the stock ( unmodified) Crosman model 100 series gets higher than 1,500psi (104 BAR) with even eight pump strokes.
shootski
PS: .25 Caliber Benjamin Marauder Update:
I raised the pressure to 3,000psi (207 BAR) before the weekend and the on-board pressure gauge still indicates 3,100psi today.
Over the weekend, between projects, i cleaned the bore with a Ballistol® wetted patch followed by seven to eight dry patches to include two dry doubled patches until they showed clean.
I removed the barrel shroud to inspect the barrel exterior and crown. Crosman’s technique for forming the Choke leaves obvious radial tool marks on the last 3/4” (19mm) the exterior of the barrel at the muzzle of the actual barrel. The dry double patch FEEL through the bore was smooth and the choked area caused the most resistance to the pull through.
I did fire one Blank (airblast) and although done inside a hard surfaced room the sound moderation with the integrated baffles only was impressive for .25 caliber. I anticipate that the addition of the DonnyFL SUMO moderator will make this air rifle very urban yard friendly.
More as i find time between projects ;^)
PPS: US Refinery technology and existing Refineries are well prepared to economically CRACK Orinoco Belt crude oil.
Shootski,
I agree that the 100’s pressure probably never tops 1,500 psi / 104bar. In fact I bet it tops out even a little lower.
BB
shootski,
I picked up a P-Rod at the NC Show this year. I have yet to test it any. I have been waiting to put a collapsible AR type stock and a Hawke red dot on her. I think she will be a nice little pester and feral soda can popper.
I have been rebuilding my new/very old .177 Discovery that I also picked up at the show. She is one of those with a walnut stock. She also leaked like a sieve when I brought her home. She is holding air very nicely now.
I also picked up a .177 Maximus and thanks to Fawlty Manuel I now have a .25 HW90. Mrs. RR is not very happy with me right now. I was supposed to get rid of stuff, not bring more home.
RidgeRunner of the Peeples Demakratik Republik of Virginia 🙁
Guess FM did a little better in the “clear out the inventory” department than you did, in 2025. Two went out but one came in; Mrs. FM did not seem to care much one way or the other. She was more concerned about the loss of her garage space last summer but she is getting over it.
Will admit that, had you not picked up that Maximus, FM would have. Then there would have been no net change to the resident number of “ladies” in Casa FM.
RidgeRunner,
My Discovery is one of the first ones …028 in the Walnut it took years before it finally started leaking having learned the RWS Chamber Oil drop trick on my very first PCPs. The Single and Multi pump owners had long known to lube their O-Rings and Seals; many using MAC1 Tim’s Secret Sauce.
shootski
Have found the .22 Marauder fitted with the Donny Fat Boy moderator to be very backyard friendly, shootski. Vewy, vewy quiet.
FawltyManuel,
How can you see past that Fat Boy? LOL!
shootski
Hey, that’s reader Elmer Fudd’s line. ;o)
BB,
It’s nice to have another historical airgun reviewed.
Will your review be pretty much the same as a new airgun? I would be interested to see how this ‘old timer’ stacks up against the new ‘young guns’ (I’m thinking that it should do quite well, in comparison).
Keep up the good work.
Bill
Bill,
Yes I plan to do all the same tests and it appears there are some extra things I need to test.
BB
Tom,
It would be nice to see how accurate this rifle is with current day pellets. Unfortunately you don’t have much data I think on the accuracy of the old pellets.
Siraniko
Siraniko,
I might also test it with old pellets.
BB
BB,
If you need some old .177 pellets, I am well supplied with them. They were made in the UK.
RR,
Thanks. I have a few oldies, as well. I think I’m good but thanks.
BB
Crosman “ash cans” vs. JSB .22 Express or Air Arms Falcons?
RG,
This one is a .177 pumper, not .22. Mine is a .22.
Oh yeah. I stand corrected. Luckily, they make .177 caliber versions. But you get the idea. I’ll sit down now.
That’s a purty gal you have to dance with there, BB. Seems the “they don’t make them like they used to” cliche fits it – hope she’ll be dancing for you many more years.
FM,
I am not sure of BB’s, but mine is all steel. That is compression tube, internal parts and barrel. The receiver is aluminum. I am not sure, but I think the wood on mine is walnut.
These things are built like the proverbial tank. They have to be messed up pretty bad to not be rebuildable.