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Education / Training Crosman 1377 – Part 2

Crosman 1377 – Part 2

by B.B. Pelletier

Part 1

We sure heard from a lot of readers on the first report of the Crosman 1377. Of all who responded, only one didn’t like the gun, and he was a Canadian who later learned that we have a more powerful version in the U.S. The rest of you seem to be split 70/30 in favor of customizing the pistol vs leaving it stock. The No. 1 custom feature is a pair of wood grips, and Ralph Brown’s name came up more than once. Several said that grips are easy to make, and I agree.

Some of you also mentioned the steel breech that Crosman sells out of the Custom Shop. This is a DIY project that I’ve been assured is not beyond most of you. I’ve done the job with other Crosman CO2 guns that are quite similar, and I’ll add my vote that a breech swap is pretty easy.

Today, I’ll do the velocity testing. I learned some very interesting things about this pistol as I shot it, and I’ll pass them along as we go.

Test 1. Velocity as it relates to the number of pump strokes
For this test, I used Crosman Premier 7.9-grain pellets. The purpose is to show the relationship between the number of pump strokes and the velocity.

10…515 (No air remaining after shot)
11…520 (No air remaining after shot)
12…515 (No air remaining after shot)

We can learn several things from this chart. First, the velocity increase with each successive pump stroke diminishes. From 3 pumps to 4, the additional stroke raises the velocity 48 f.p.s.; but, from 9 pumps to 10, the increase is just 16 f.p.s., or one-third as much. Also, while 11 pumps did produce greater velocity than 10, pumping once more actually slowed the gun. So, 10 pump strokes should be considered maximum.

I also noted that the pistol warmed up considerably during this test. A second test revealed some interesting numbers.

Test 2. Velocity as it relates to the number of pump strokes after the gun became warm

10…474 (No air remaining after shot)
11…486 (Some air remaining after shot)

Some velocity was lost between this test and the first. I thought this was due to the gun being warm, but later testing revealed that wasn’t the case.

Test 3. Velocity after waiting 3 hours for gun to cool


I shot only three times because we know the other shots will lie at their respective places in the string. Obviously, the gun has settled into a slightly lower velocity after a short break-in. Did the over-pumped shots have anything to do with it?

Test 4. Velocity with other pellets
The surprise was that Hobbys weren’t much faster than Crosman Premiers were on the second test.

RWS Hobby

RWS Superdome

JSB Exact 8.4-grain domed

Test 5. Velocity with other pellets, after oiling
In this test, I oiled the pump head with Crosman Pellgunoil before starting. I put in 9 drops and worked it into the pump chamber after every 3 drops by partially pumping the handle without completing the pump stroke.

RWS Hobby

RWS Superdome

JSB Exact 8.4-grain domed

Oiling increased velocity a little by helping to seal the pump head. It also goes through the gun and gets on every seal along the way. This is a real health tonic for a pneumatic airgun.

Well, the 1377 is certainly not 600 f.p.s. with any pellets I would use. However, in the interest of fairness, I did try the gun on 10 pumps with Crosman Silver Eagle hollowpoints. They averaged 604 f.p.s., so this pistol met spec.

Pumping not difficult
Unlike a pneumatic rifle, the pump strokes don’t seem to get much harder as you approach 10. That’s always been true of multi-pump pistols. I suppose it has to do with a smaller compression chamber, but I’m not sure.

Next time, we’ll try her on targets and see how accurate a 1377 is.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

50 thoughts on “Crosman 1377 – Part 2”

  1. My shooting is game mostly.Rabbits, some squirrels. Tried one of these Crosman’s. Not enough power. Too much plastic. Bought a Benjamin .22 and a set of wood target grips. Perfectly happy now. I always opt for a .22 where available.

  2. After reading this article I was thumbing through an old issue of Popular Science (Oct. 1942).
    I noticed an ad for the Benjamin Target Pistol, similar to the current HB. The price with 500 rounds was $10.50 in .177 or .22.
    Times have changed.
    Keep up the good work, everything I know about airguns I learned from this blog.

  3. Hia BB and Company,

    Well as always I enjoy the stories and reviews.

    Starting with the first part of the 1377 blog, I knew it was time to shoot mine again.

    My 1377 is an early version August 1984, by serial number. It has the plastic breech, but it still has a separate pull to cock bolt, and a magnetic tip breech bolt to hold BB's. Although I don't remember shooting BB's much.

    I have used this since it was new and always enjoy shooting it.

    I was thinking my velocity was a bit low, so I tried a few different seals, only to go back to the original. During that time I replaced the front breech screw, with a 4-40 flat tapered head I found in my RC parts box. This was my best improvement because I was able to get a tighter fit from breech to air tube. Funny thing is at 5 pumps I did not get a big increase, maybe around 5 to 10 FPS. Where it did gain a lot was at 10 pumps with heavy pellets about 20 to 30 FPS gain. I'm assuming the greater resistance of the heavy pellet was causing just a bit more air to escape from the seal.

    Well anyway it seems we are shooting the same velocity.

    RWS Diabolo Basic 439FPS @ 5 and 520 FPS @ 10 pumps.

    Crosman CPL 421FPS @ 5 and 495 FPS @ 10 pumps.

    RWS Super Point Extra 418 fps @ 5 and 495 @ 10 pumps.

    8.4 gr. JSB Exact 407 FPS @ 5 and 485 FPS at 10 pumps.

    H&N Barracuda Match 374 fps @ 5 and 448 fps @ 10 pumps.

    OH yes the Crosman Silver Eagle 510 fps @ 5 and 600 fps @ 10 pumps.

    Something made me look into the old manual and sure enough Crosman states with a 7.9 grain pellet 485-510 FPS at 10 pumps; 430 – 455 fps @ 6 pumps and 310 – 385 fps @ 3 pumps.

    So after this long winded comment it boils down to the gun is shooting where it was intended.

    And yes I did notice the compression tube warming up as I was testing. I thought it was just my hands causing that but know I’m not sure.

    Joe G from Jersey

  4. The more I read about the 1377, the more I regret not buying one. The only down side I can see to woning one is that here in Michigan, it must be registered as a firearm. This leads to potential legal problems if you want to customize it as I do.

  5. I have an early model 1377 with a plastic breech and sliding breech cover. I was told by Crosman that this 1377 could not be upgraded to the steel breech that they offer. Does anyone have any input on this as the steel breech would allow me to mount a scope on what I think is a good target pistol. Thanks.

  6. richard,

    Your 1377 is most likely the same as mine a Phase 2. From what I can see the new style cocks with the breech bolt and ours has the seperate cocking bolt. So I see that as a problem for the steel breech kits working on Phase 1 and 2 1377’s. I would still like to view the the breech kit in person, to see if it can be made to work.

    I tried the scope mounts on mine but the barrell can twist ever so slightly.

    Joe G from Jersey

    • Joe, For some reason I believe the Crosman steel breach will fit and work on your older [phase 2] #1377. I believe you must cock both the steel bolt and the pull back knob – not a big problem and possibly a good safety consideration. I remember reading about an issue with your older barrel being slightly different than the later #1377’s at the back of the barrel where the bolt [either the Crosman bolt and /or the steel breech bolt?] enters the barrel and or where the air transfer port/seal enters the barrel. In any case try sealing these areas with Loctite GO2 glue – it’s removable and easy to work with. The Crosman scope intermounts [Part 459?] need a shim about the size of a postage stamp under each mount [two shims] and about 0.020″ thick. I use a shim cut from the sidewall of a large backyard swimming pool This needs to fit snugly under the barrel [use a standard screwdriver to lift the barrel a bit to install] and a few drops of the GO2 glue under the shim and between the top of the shim and the two feet on the intermount help secure this. Just for fun I’ve mounted a large BSA scope [6 x 18×40 AO – Sweet 22, 19″ long and 20 oz.] for a Bug Buster – works fine but needs a carbine stock to steady. Also have tried several other somewhat smaller scopes [Sun Arms Shorty Forty and Center Point 4 x 10×40 AO] with fun results = great accuracy [I bug bust (flys) at 40 to 50 feet] – I believe Pyramid Air has some post on using the steel breech on older style [double cock] 1377’s. I have a 1982 -#1377, had a steel breech cover/ converted to 2289, used the newer 1322 plastic-breech/brass-bolt, added a 24″ barrel – works fine at 6 to 8 pumps and stock pump. Also the GO2 glue is great for gluing the barrel tight on any of these guns – only needs a 1″ strip at the breech and 1/2″ strip at the muzzel – needs to be put on in several layers because if put on too thick it runs down the side of the barrel – just hold it and turn as needed to keep it in the area between the barrel and pump tube – it’s clear, hard and easily removable [just use a skewer stick or a sharpened popsicle stick to break it out and scrape it off if you need to repair the workings inside the gun. Good Shooting

  7. Joe G from Jersey, from a fellow ex-New Yorker living in NC! Thanks for your response. I too would like to see the steel breech for comparison. I was almost tempted buy the breech from Crosman but better judgement tells me that it won’t work for the same reasons that you stated. Other than an expensive modification by a person who knew what they were doing, it would just make sense to buy a newer model on the used gun market that already has a steel breech. Thanks for the help.


  8. Richard,
    to use the steel breech, you need a new barrel. The new bolt won´t fit the old barrel.

    The separate cocking is no problem, but you can´t use it the other way. A new pistol with an old breech can not be cocked.


  9. I had to shim my loose plastic grip. Added a 4×15 scope on the barrel. Use some rubber from an innertube on the barrel mount to keep the barrel from rocking a lot. Found a hard to find pellet (Beeman coated hollow points style 1222 grey Chinese made work fine also gold German made ones avail.) to get about 5mm groupings at 10 Meters.

    For hunting, no. Head shots on small birds or mice only. Mainly used for fun.

    Air rifles will most likely deliver more performance for the money. I believe for target competiton a model with a lothar walther barrel with better adjustable open sights are a must.

    Very nice upgrades, but for targets I would say save your upgrade money and get a try a Daisy Avanti 747 or IZH-46.

  10. BB,

    After reading your first blog on the 1377 I bought one as my first airgun. The only thing I have done was replace the plastic grips with some RB wood grips (www.rbgrips.net) which really add a quality feel to the gun. I only use it for plinking in my back yard, and it is perfect for this.

    So far I’ve put about 1200 shots through it and it feels like it will last a lifetime.

    Its also great for teaching, I taught my wife how to fire a pistol with this gun and she now holds the ‘range record’ in our yard, hitting a small hanging tin man at 35 yards, 17 times in a row!

    This $55 has been some of the best around the house entertainment I have ever bought. Anyone looking for a pistol plinker that doesn’t take Co2 should really check the 1377 out.

    Thanks for the recommendation and I always enjoy your blog even though this is the only airgun I own.

  11. BB,

    How exactly do I oil the “pump head”?

    Do you recommend doing anything else over the life of the 1377 to keep it working as good as possible (like oiling anything else)?

    And lastly, how do you recommend storing this; empty, with a pump or more?

    -newbie in wy

  12. Newbie in WY,

    For oiling the pump head, look at the photo on the bottom of this report:


    The gun is lying on its back with the pump handle extended.

    Always store a pneumatic with a pump of air, if possible.

    The more you use the gun, the longer it will last.


  13. BB: Thanks for your responses on the oil/pump head questions. Do I take it, then, that every pneumatic can be oiled in this way (I also have a Benji 397 that doesn’t have very clear instructions about oiling). For the relatively short time I’ve been into airgunning, I’ve been hesitant to use much oil because I have read that you can over do it and damage a gun.


  14. Thanks for the quick reply. I just ordered the1377c from pyramydair, I guess I’llcall them in the morning and change. Two more questions. I see you recommend oiling, does the gun come with oil, or do I need to add it to my order. Also, which pellet is best for accuracy?

  15. You must oil the pump piston head if you want to heep the pistol working.

    No oil comes with it, so get some.

    The 1377 shoots most pellets very well. Did you read part 3 of this report?


    As you will read, RWS Meisterkugeln pellets were the most accurate tested.


  16. Actually, I was just getting to it (Part 3). It’s because of your review, I decided to get this gun. I’ll imagine you like the 8 grain better than the 7?

    I’m going to rid myself of a particulary pesky squirrel who has been causing quite a bit of damage to the patio furniture. After that, I’m going to try and get good at target shooting.

    Also, your statement on the sights leads me to believe that you ended up putting them back where they were in the first place. Is that correct?


  17. Hi, B.B.!

    Received my 1377 today. I have a few quetions, if you don’t mind. Is this the proper venue to ask? If not, loet me know where you would prefer and I’ll re-aske them there.

    First, they sent me the wron (maybe) ammo. I asked for the 250 /tin, which I thought was for the pistol, but they sent the 500/per tin, which is supposed to be for rofles. Will this harm the gun? Be less accurate?

    Second, based on your posts about oiling, I oiled it before I tried a shot (I’ve only tried it twice, both times with 5 pumps). I’m not sure if I’m putting oil in the right places. There’s a pair of small hoels in the large tube under the barrel, which I’m gussing is the pump. Put oil in there? I put some on the front of the breech bolt, which appears to have a small seal. I also put some on the plunger – nearest the back of the gun when the pump handle is fully open whe looking at the gun upside down, as best I can describe it. Did I do tis right?

    Third, I took two shots at a tree from about ten feet, but saw no clear mark. Would the pellets make a mark or embed themselves in a tree, or is it possible that I completely missed both times due to poor marksmanship, which is highly likely since I’ve never owned a gun and/or the gun is way off? Is there any easy way to test the accuracy of a gun when you aren’t an experienced shhoter?

    Thnaks for all your help. This appears to be a fine beginner’s pistol. Just hope I can figure out what I’m doing.


  18. Jim,

    Since you don’t mention the brand or model of pellets, I can’t say, but you cannot harm this gun with pellets. Just stay away from Raptors.

    250-500 per tin are often the same pellet.

    Second, oil the pump piston head per the instruction manual. That’s [paragraph 7 of the manual.

    Finally, shoot at something you can see. Trees are not good targets. Shoot at a soda can.


  19. BB,

    I have an older model 1377 with a smooth breech cover (no handle)and a cocking knob at the rear. It shoots BBs and pellets. I’d like to replace the plastic parts (forearm and grips) with wood. Could you recommend a website with instructions for this procedure?


  20. According to the Crosman manual for the 1377 – The following Muzzle Velocities are shown.

    Pumps Velocity Projectile Weight
    3 350-385 .177 BB 5.5gr
    6 460-510 ” “
    10 530-570 ” “
    3 310-345 .177 Pell 7.9gr
    6 430-455 ” “
    10 485-510 ” “

  21. Just finished converting my phase 2 1377 to the Crosman steel breech. This conversion can be done and it makes a huge difference but you also have to replace the barrel with a phase 3 model as the chamber is different and the phase 1 and 2’s won’t load properly. I’m very happy with the results and highly recommend it.

  22. I reduced the trigger pull by opening the handle and removing the spring. I compressed it with a set of pliers and reinstalled it.

    Although the trigger is still creepy, the pull is light enough that the gun doesn’t jump or vibrate. Instead the pellet hits the target and the gun remains on picture.

    What a great little gun!

    I found the Crosman Pointed 7.9gn pellet is very accurate and has the same ballistic coefficient as a Beeman Kodiak.

  23. ….and put a dab of dayglow paint on the back of the front sight post. It helps in getting the sight on target.

    I use the top left corner of the post as my point of impact to help keep my aim small.

  24. Why should I stay away from using raptor pellets? Well they damage my 1377c? I have shot about 25 of through it before I read your articule. Hope I havent damaged my gun. I also use Polymag predators for gophers and rats they are deadly on small animals and birds and ground squrrels I use H&N finale match for target shooting they shoot better than I can hold them also Misterkugeins are very good too! I love my 1377c

  25. Bryan Merritt,

    I'm trying to help B.B. answer comments today.

    You may want to check back in a few days since he may add to or modify my answer to you.

    Raptor's are a lightweight overhyped, overpriced, hard pellet. I think raptors are made out of zinc and sometimes plated. I'm assuming that B.B. advised against using a raptor pellet because of it's hardness and rare accuracy.

    I don't think shooting 25 raptor pellets in your gun has done any harm. Has your accuracy changed with your other pellets?


  26. I have had my Crosman 1377 for about a year and a half. Overall it is a great gun, but recently it started leaving
    some air in the valve. Sometimes a lot and sometimes a little to none. ( average of six to ten pumps ) I have tried a heavier hammer spring and a lighter valve spring. The hammer travel seems smooth and the valve parts look OK. The gun has the steel breech and an eighteen inch barrel. Any thoughts to what may be causing this?


    • Dan,

      As you suggest, it has to be the valve/striker relationship. But it may not be a stronger striker spring that you need. A heavier striker might increase thr valve dwell time — especially with that long barrel. And what is the condition of the valve return spring? If it has rusted or kinked it may not be allowing the valve to open long enough. Or if the valve stem is bent it may do the same thing.

      If the gun has been over-pumped a lot, that is enough to create this problem.


  27. Love this blog. Just did a steel breech conversion tO my 1377. Still have the standard barrel. From what I have been reading, should I have the 18 inch barrel with this steel breech now? I do plan on scoping this gun as well. Thanks.
    Jim in San Jose

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