Sheridan Blue Streak: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Sheridan Blue Streak
My Sheridan Blue Streak dates back to 1978 when I bought it new.

Part 1

A history of airguns

This report covers:

  • Lots of pellets
  • Test plan
  • Crosman Premiers
  • Huh?
  • Consistency
  • Last test — Benjamin Cylindricals
  • Pump effort
  • Discussion
  • Summary

Today I test my Sheridan Blue Streak’s velocity. If you read the test I did in 2016 you know that I had the rifle resealed by Jeff Cloud at that time. Up to that point it still had the seals that were installed at the factory in 1977 when the rifle was made, so that’s 39 years on the first set of seals.

Before resealing the rifle, .20 caliber 14.3-grain Crosman Premiers (a pellet that’s no longer available) made 462 f.p.s. on 8 pumps, where the manual says to stop, and it went 476 f.p.s. on 10 pumps with no air remaining in the gun after the shot.

After resealing the rifle, the same Crosman Premier pellet went 582 f.p.s. on 8 pumps and 609 f.p.s. on 9 pumps. After 9 pumps were shot there was air left over in the gun, so 8 pumps was the effective maximum after resealing. That is a gain of 120 f.p.s. or 86 f.p.s., depending on which former velocity you accept as the top.

Following Part 4 of that series, which published on October, 2016, I put two pumps of air in the rifle and never touched it again until this report started on July 15 of this year. Actually that wasJuly 13, because I usually have to test my guns before writing about them. Still, almost three years had passed and the rifle was still holding air when I got it out.

Lots of pellets

I have plenty of .20 caliber pellets for this test. They range from the older Sheridan cylindrical pellets that came from a yellow plastic box that was purchased in the 1990s to several cardboard boxes of Crosman Premiers I have saved over the years. For modern pellets I have the following.

.20 caliber H&N Baracuda
.20 caliber H&N Field Target Trophy
.20 caliber Predator Polymag
.20 caliber JSB Exact
.20 caliber Benjamin Cylindrical

That’s all the .20 caliber lead pellets Pyramyd Air stocks except for the JSB Exact Heavy. I plan to test all of those on hand for accuracy, but not for velocity. Their weights should tell us how fast they want to go, give or take a little. What I’m interested in testing is where the rifle is today, so we know where we stand going into the accuracy test.

Test plan

Today I will test the Blue Streak with Crosman Premiers in the same way I tested it in 2016, so we can compare. I will test velocity with 3 through 9 pumps and then I will test consistency with 5 pumps. Let’s get started

Crosman Premiers

This first test is with the Crosman Premier pellet that’s now obsolete.

Pumps……..Velocity
3……………..453
4……………..516
5……………..557
6……………..600
7……………..626 (no air remained)
8……………..651 (no air remained)
9……………..665 (no air remained)

Huh?

Okay — what just happened? I don’t know, but after sitting for 3 years with 2 pumps of air inside, my Blue Streak is now either 83 f.p.s. faster on 8 pumps than immediately following the reseal in 2016 (if you go with what 8 pumps did back then), or 56 f.p.s. faster (if you go with what 9 pumps did back then). Either way, it has picked up some real velocity!

Consistency

Now let’s look at how consistent the rifle is when pumped the same number of times. I will fire 5 Premiers on 5 pumps each for this test.

Shot………..Velocity
1……………..562
2……………..552
3……………..553
4……………..556
5……………..543

Across 5 shots with 5 pumps each, the Blue Streak shot Premiers within 19 f.p.s. of each other. And only shot 5 was slow. The other 4 are within 10 f.p.s. of each other.

Back in 2016 after the reseal during this same test the rifle stayed within 73 f.p.s. for this same test with the same pellet. But it seemed to be warming up as I shot that first string, so I ran the test a second time.

The second time the rifle delivered the same 19 f.p.s. velocity variation for 5 shots on 5 pumps each that we see in today’s test. The same Premier pellet was used and the average velocity for the second run was around 543 f.p.s. I attributed that to the new seals warming up as the gun was shot. But they may have just been breaking in. At any rate, the gun is faster now than it was 3 years ago. Apparently multi-pumps do need a short break-in period after a rebuild before achieving top performance.

Last test — Benjamin Cylindricals

I know the Premier pellet I’m using for the tests is obsolete and unobtainable. So, to bring this test into the modern timeframe, I also tested it with variable pumps while shooting the new Benjamin Cylindrical pellet.

Pumps……..Velocity
3……………..456
4……………..509
5……………..548
6……………..560
7……………..590 (no air remained)
8……………..621 (no air remained)
9……………..634 (no air remained)

Pump effort

Now I measured the effort needed for each of the effective pump strokes.

Pumps….Effort lbs……2016 lbs.
3………….30…………..30
4………….34…………..32
5………….36…………..35
6………….39…………..35
7………….42…………..37
8………….42…………..37

The effort to pump has gone up up a bit. That may indicate that the rifle is pumping more efficiently today than it was in 2016.

Discussion

Now we have a good baseline for the rifle and are ready to proceed to accuracy testing. I will start with the Crosman Premier pellet that proved so accurate three years ago. I may test that pellet with a different number of pumps to see if there is a best number. But with all those other pellets I will certainly see what it will do with each one. Perhaps 5-shots groups for most of them, because this is a multi-pump?

Summary

This Blue Streak continues to surprise me. I have owned it for 41 years and I’m still learning things about it. What will come next?

74 thoughts on “Sheridan Blue Streak: Part 2

  1. B.B.,

    Good to see your Blue Streak is working at optimum performance after a nice nap. All the numbers look very good. I expect the accuracy to follow along with the velocity and be very good.

    Maybe this would be a good time to stretch its legs out further than you have in the past. Old reliable deserves a chance to show what it’s got. Is the scope mount from the Steroid Streak by Tim McMurry still available? That would be interesting at longer distances.

    Don


  2. G’day BB,
    I was just looking at a yellow plastic packet of Sheridan 500 cylindrical lead air gun pellets in 5mm(.20 cal) in my desk draw costing $18Au….ahhh memories!!!
    I bought a Sheridan Blue Streak new and could NEVER get a decent group. I was told to scope it which I did and that did not improve accuracy. I took it back to the gun shop for them to check it out and a couple of days later they gave me it to me back with the a beautiful 10 shot group. I told them I could shoot that group anytime at 6 inches so do it in front of me.They declined and I got my money back.
    I was then introduced to Beeman and Theoban, now that’s love at first group!
    Cheers Bob


  3. B.B.,

    Looking good. In the “Discussion” section,… you seemed to ask if we thought 5 shots per target would be ok for the accuracy phase of testing. I think 5 is fine. That is a huge amount of pumping after all. Take it to 10 shots if a pellet shows promise.

    I agree with Don,.. maybe stretch it out a bit if you feel it is appropriate.

    Good Day to you and to all,……. Chris



  4. Over thirty years, I have had a Squirrel get in the house three times. With all three the Sheridan was worth it’s weight in gold. Three pumps, one head shot, no more problem!

    Mike


  5. Perhaps sitting with just that bit of air pressure in it formed the seals more precisely, over time, and hence the increase in efficiency?

    Motorman
    St. Louis, MO


  6. B.B.,

    Great read I look forward to the rest of the report.

    Reading this has me interested and wondering, have you tried out the new Benjamin Variable Pump? Seems to be just a new synthetic version of the old rifles.

    Was thinking of getting one of the new ones for my kids and I to shoot.





        • Brody
          I lived without a chrony for a long time. So no problem. I gaurentee you I will relate to what you have to say. 🙂

          And just reply to me on the current blog if you do get one. For sure would like to hear what you think.


          • Will do, I am considering getting a Fortitude for target shooting/hunting right now so I will have to see if the budget allows for both 🙂

            Also if the new Benjamin Pump is a season loud as the old one I don’t know how much my neighbors would appreciate it.


            • Brody,

              Not sure,… but the Fortitude may be louder. I have the Maximus in .22. I do love the Maximus. Points well, light and accurate. Took a 20# ground hog with a head shot at 25 yards. Clean kill.
              The Fortitude was not out yet,… or I would have opted for it. If going the Fortitude,… get the Hunter version with the screw off muzzle cap. That would allow a “moderator” if you can get your hands on one. 1/2-20 thread. That whole topic is a bit “iffy”,… but they are out there for sure. I would have to get the Fortitude if you are already set up for PCP’s,… if I was you.

              Chris

              I assume that there is in fact a Hunter version of the Fortitude. There is in the Maximus version. If PA does not list it,… check around or go direct to the source to verify that there is one.


              • I have a Discovery with a TKO that is really nice, it just doesn’t get many shots before I have to start pumping again hence the interest in the Fortitude.

                I have looked into the small compressors but not willing to commit that amount of money yet when I can fill them with a hand pump, plus I could use the little bit of exercise it provides.


                • Brody,

                  Good. Keep us posted. I just looked it up and forgot that it is shrouded and most likely has baffles at the muzzle,…. so it may be all good on neighbor noise. The Maximus is just barrel,… so not the same. Nice shot count too on maximum setting.

                  I am a big fan of regulated. I put one in the .22 Maximus and have a Red Wolf in .25 that is. Also a .25 M-rod in a RAI stock that is not regulated.

                  Exercise eh?,… I can relate. 😉 I get plenty at work,… but still a bit too pudgy. 😉 Too good a cook I guess. I have the Shoebox 10 and a CF tank,…. both of which I love. I work too hard at work. I do not want to have to work to shoot. There is better/cheaper options now on pumps from when I got mine. GF1 put one together for around 300 I do believe. He goes direct to gun,.. so no tank $.

                  Chris


              • Chris
                The Fortitude has a shroud and baffles.

                It will be quieter than a Maximus or Discovery.

                And the 392’s and 397’s are just about as loud as a Discovery or Maximus so a the Fortitude should be quieter than a 392 or 397 and the synthetic stock multi-pump cousin we are talking about.



                • GF1,

                  Won’t do. The shroud and baffles are doing enough sound reduction. Maybe at least as good as an add on/screw on. The Fortitude cap may be the same one as the M-rod cap. It would not surprise me.

                  Chris



                  • Chris
                    I’m talk’n about a hunter version of the Fortitude.

                    That’s what I’m talk’n about you do”n some search’n.

                    Show me if you know they are making it.


                    • GF1,

                      I am (not) looking for a Hunter version of the Fortitude because I know enough to know that a shrouded and baffled gun is not (likely) going to be moderator adaptable. What is add on is pretty much already there. I made that comment before I looked it up. Maybe you missed my acknowledgement of that to Brody?

                      Chris


                  • Chris
                    Here. This is what I’m talking about with your comment.

                    “The Fortitude was not out yet,… or I would have opted for it. If going the Fortitude,… get the Hunter version with the screw off muzzle cap. That would allow a “moderator” if you can get your hands on one. 1/2-20 thread. That whole topic is a bit “iffy”,… but they are out there for sure. I would have to get the Fortitude if you are already set up for PCP’s,… if I was you.

                    Chris

                    I assume that there is in fact a Hunter version of the Fortitude. There is in the Maximus version. If PA does not list it,… check around or go direct to the source to verify that there is one.”


                    • GF1,

                      To put it (super) simple,… I was mistaken in my original comment. I corrected that. It has been awhile since I have looked at the Fortitude.

                      Chris



            • Brody
              I had a .22 Benji pumper when I was a kid. It was a great gun for a kid living on a farm to have that was use to shooting 760’s and 880’s before I got it. It was a powerhouse from what I remembered.

              So I got a new 392 a while back. It shoots nice. But is louder than I remember about the one I had as a kid. But then again I was use to shooting shotguns for hunting and .22 rimfire for plinking. So that’s probably why the old Benji didn’t seem loud to me back then. And though the multi-pumps where mostly pesting guns around and in the barns and such I did plink with them too. Basically a nice overall use gun I will say.

              And if I didn’t already have a Maximus and other guns for the different categories of shooting I do. I would have a Fortitude. Heck maybe one day I might just end up with one for the heck of it anyway. 🙂



  7. B.B.
    Shortly after being convinced (by you =>) to buy a chronograph, I started checking velocities on my old guns; with the Sheridan, I got the following results:
    Sheridan pellets (15.5 g) RSBs (13.73 g)
    2 pumps = 301 fps 2 pumps = 370 fps
    3 pumps = 403 fps 3 pumps = 451 fps
    4 pumps = 468 fps 4 pumps = 522 fps
    5 pumps = 530 fps 5 pumps = 555 fps
    6 pumps = 570 fps 6 pumps = 618 fps
    7 pumps = 607 fps 7 pumps = 654 fps
    8 pumps = 645 fps 8 pumps = 689 fps
    One of the old Sheridan ads claimed a pellet weight of 16 grains; but I have seen weights of 15.5 to 15.7 grains from people who weighed a batch of them and divided the results to get an individual pellet weight.
    Going with the lowest (15.5 g) makes this a just over 11 ft-lb gun at 6 pumps (which is all I ever used in it), or 11.6 ft-lbs using the more efficient JSB pellets. And I hunted all many of critters, but mostly squirrels, with this gun for years, and it worked quite well…so perhaps our brethren across the pond in the UK are not all that handicapped with their 12 ft-lb limit. =>
    At one point, I had this made into a Steroid Sheridan; but I never liked that, at 14 pumps, it would not exhaust all the air. I was always afraid it would mess up the accuracy if I put 14 pumps into a gun that still had air from the last shot, so I would cock the bolt and fire the gun with no pellet to exhaust all the air before preparing for the next shot. Then we moved to a place with less room to shoot, and I had Rick Willnecker convert the gun back to factory specs. It’s about in the same power ball-park as your Sheridan (13 to 14 ft-lb max), which I think is fine for these old guns.
    I was just re-reading this report you wrote back in 2011 on the accuracy of vintage Sheridan pellets:
    https://www.pyramydair.com/blog/2011/12/are-vintage-sheridan-pellets-better-than-modern-pellets/
    I did some limited accuracy testing a few years ago, and the JSBs were so much more accurate than the vintage Sheridan pellets that I put the “yellow box” up on the shelf, just kept for nostalgic purposes.
    Looking forward to your upcoming accuracy report,
    dave



      • Awesome B.B., I am looking forward to it! =>
        In the meantime, I did dig up one target that I shot back in 2014 using Sheridan “yellow box” pellets.
        I believe I read your report on Sheridan pellets, then had a few people tell me, “JSBs are much better!” So I bought some from PyramydAir. But I believe I was shooting in the garage that day (raining? can’t remember…that was 5 years ago, and I can’t even remember what I had for breakfast today!), and that’s why the target was only at 20 feet. Anyway, my 3-shot group was about 0.68″ with the vintage Sheridan pellets; and though I can’t find the target, the group with JSBs was just a ragged hole at that range.
        *shrugs*
        I realize that is not exhaustive compared to the testing you do, but you are working for the entire airgun community, whereas I just had to satisfy…me. =>
        The quick test showed me that the JSBs had enough more accuracy to make the switch, and they are all I have been using ever since.
        Thanks again!
        dave


  8. A friend of mine that I know from our Wednesday chess group (I call us the “Chess Geezers”) has an old Silver Streak. I told him that that is an air rifle that is quite highly thought of among air gun shooters. Haven’t seen it, but he says it’s a potent tack driver.



      • Ha!! I do love me some chess. Used to play in tournaments too. My favorite one was the National Open in Las Vegas. I played in on there with just over 1100 players. I’ve given up on tournament play due to the meds I’ve been on for two years now. I do okay at the geezers each week, but I’m not sharp enough for tournaments.


  9. Hi B.B!
    Since I only acquired my Sheridan CB Blue Streak (dec.1972) a few months back, I am especially glad that you decided to re-review your Blue Streak!
    I have only shot the Benjamin 5mm cylindrical lead slugs, and my own chronograph tests consistently average around 680 fps with the Benjamins
    It is just such a marvelous air rifle, and it’s really too bad that Crosman did what they did with the Benjamin & Sheridan product lines.


    • Spinoza
      You are going to love that rifle! It was my first airgun ever; I wanted one for years…and it took me years to finally convince my Dad to let me get it…but it was worth the wait. =>
      May you enjoy it,
      dave


      • Dave,

        You brought a big smile and some memories with that comment. Being young and just (having) to have “something”. 24/7 thought consuming. 😉

        I was shopping at an Aldi today (discount foods, but excellent) and in front of me at the check out was 2 young boys,… an older brother and younger brother, I assume? 10 and 8? At any rate,… Mom was just ahead in line (BUT) the bar was in place between her goods and the boys. What were the boys so intent to spend in what I assume was their hard earned money on?,………… Pokémon something or other,… in a tin. 2 tins. Small tins.

        Now,…. I pretend to know nothing about Pokémon,… or tins. Point is,…. those 2 boys just HAD to have whatever it was in there.

        The older boy pulled out 20 cash in a mix of bills and the younger boy fumbled for the additional 2$+ something. Yea,… 22+ something!

        It was interesting to see and reflect upon.

        Chris


        • I hear you, Chris! I know little about Pokémon; but that’s not the point; the point is like you said: being young and just having to have something. =>
          For me, at 6, 7, 8, 9, and10, it was that other gun B.B. reported on…the Daisy Buck 105.
          And that’s the other reason (besides the $14 sale price) I just HAD to get it.
          When 60-year-old-dave bought it, then went out and shot it in the backyard, he could feel 6-year-old-dave laughing on the inside…happy that he’d finally got his BB gun. =>


          • Dave,

            At least the Mom was wise enough to let them have a go at it. Hopefully it will be a (lesson) when some years later they realize that Pokémon stuff will just be a passing fad and collecting dust. None the less,… it was a joy to see the interaction taking place. Hopefully the money spent was hard earned. That (does) have a way of driving the point/value of money,… home. Money gone, want more, must work for more, not that happy with my last purchase,…. maybe I will spend it better/wiser next time? If only we knew then,.. what we know now. 😉

            Chris


  10. Hi BB,
    We’re going to be treated to the dime on Monday when you report the test of the JSB Exacts! I rebuilt a friend’s rocker safety Blue Streak about 5 years ago using the nice rebuild kit sold by Pyramyd. I bought him some JSBs at the same time. At 10 meters his Sheridan with Williams peep grouped the JSBs really, really well. My prediction is you are going to show us better than 0.23″ group for 5 shots, or better than 0.34″ group for 10 shots, shooting JSB Exacts at 10 meters. The groups will be nice and round too! And, because the pellets are domes, the groups will look extra tiny. It’ll be a fun read on Monday!
    -Andy


    • Well I guess if that’s how someone wants to use the gun.

      We never shot at 10m when we was kids. Even pesting. That would be a treat to have a mouse set still at 10 meters. It would be gone before we shouldered the gun.

      From what I know. I want minimum 15 yards if I’m pesting. If not more for minimum shots. I know what my old Benji and new Benji does.

      But yep know what you mean about target shooting too. I hope this gun BB is reporting on will do at least a penny at 10 meters. We’ll see.


      • I have about 13 yards in my basement and a little 10m lane marked off from the washers past the workbench and bike stand, so that’s what’s convenient. We sometimes shoot together outdoors at a friend’s house, but it’s a pretty rare event and a little bit of a production to organize. Everyone is always busy chasing kids and also busy with parents and in-laws.

        As kids we shot the very same Sheridan at acorns, pine cones, and such targets of opportunity. Did a little unofficial pigeon, rabbit, and squirrel hunting. But, I couldn’t hit with it back then, probably didn’t understand the peep. I was pretty good with the Daisy 880 though for some reason, so that was the one for me usually. The Sheridan also sometimes accompanied us walking the trap line we set for raccoons because it was the best we had for the dispatch job, but that turned ugly, as you can imagine, and we rethought things and one of us borrowed a .22 pistol for while. I’m talking about being dumb 14, 15, and 16 year old boys!


        • Rillburgher
          At least you got your downstairs range to use when you want.

          And I know what you mean. We put those old multi-pump guns through their paces when we kids. But I have to say it was a very rare occasion for one us kids not to have a .22 rimfire or shot gun with us. It felt kind of like now days when you forget to take your phone with you. It didn’t feel right without the rimfire or shotgun there.

          But anyway. Yep was some good times back then. But have to say me and my daughter’s are having our share of memory making now days. Shoot’n, 4 wheel’n and fish’n. And I don’t plan on stopping anytime soon. 🙂


  11. Love reading about these old classics. I am 62 and still own my Blue Streak with the factory installed Williams peep that my dad bought for me in 1970. Never been resealed, but always stored with 2 pumps. Holds air for years. I grew up in Racine, so all my friends had Sheridans as well. I found a beautiful Supergrade a few years ago, so these two are my favorites. Still use both regularly for chimpmunk control.








          • B.B.,

            Those are filled with Helium…not Hubs!

            I think I understand the issue as one of portion control. I almost lost that battle 15 years ago.
            The good Lord had given me a body and I had let his Temple fall into disrepair. He provided the strength of will to overcome my failure to honor his gift of a well functioning body.
            My seakayak paddle group has the Motto: We paddle farther to Eat!
            In the winter time I XC ski in a thin layer of Licra at below freezing temperatures so I burn more calories and I can eat almost everything I want to now. I hunt on snow shoes and switch to skis when the snow gets deep enough to cover all the brush and small boulders. I go lightly clothed and carry my layers and a bivey in a backpack for emergency use. At 70 it does take more to get going and also more effort to burn enough calories to keep the extra girth at Bay! But I wouldn’t do life any other way. Even three brisk walks a day of 10 to 15 minutes can get the scale and tape measure to show significant progress.

            Being in reasonable shape makes it much easier to shoot well to boot!
            End of my fitness Sermon to you and your readership.
            Blessing of health and fitness,

            shootski


    • R.R.,

      Why are you trying to drive Tom NUTS?
      Some time back we discussed that Hubbard Peanuts were now available for direct orders.
      Love that kind of general store.
      You are lucky to still have one.

      shootski


      • Shootski,

        LOL! He is the one who started me into collecting antique air rifles. He is also my main supplier. The majority of my airguns are older than you, BB or me.

        The Emporium is awesome! I do my best to conduct as much business with them as possible. Phillip is always dressed as you see in his videos and on their sites. He does his best to stock only products made in Virginia. He is also an avid historian and loves to talk.

        I also enjoy doing business with the local grocery store, gas stations, hardware store and auto shop. I do my best to support my local community and in return they help support me. Ya’ll can have the big cities. I’m just a dumb ole country boy.


      • Shootski,

        By the way, there are no traffic lights in the entire county. A traffic jam in New Castle consists of four cars following along behind a riding lawn mower being driven by a guy who has had his drivers license suspended. There happen to be two of them, a red one and a green one.


  12. Off and on we talk about shooting single shot or with a magazine and the effect it has on accuracy. Today I shot some targets with the magazine in my RAW HM1000x LRT at 40 yds. I was surprised to find that the JSB 15.89 gr Exact Jumbo Diabolo pellets were not doing well. They have been good in the past and they seemed not to be feeding smoothly like normal. Here are two groups. The magazine group only has 5 shots because I knew something was up. I will be taking the magazine apart to see what is up with it. I have shot the 15.89 JSB’s before with the magazine without problems. I usually shoot the JSB jumbo 25.39 Monster Diabolo pellets because they are more back yard friendly. The lighter pellets are quite a bit louder.

    Here is a target showing the big difference with and without the magazine. I think the frist shot in the second group may have had some debris in the barrel or the moderator from the pellets that were deformed from the magazine.

    Don



    • Don,

      Not sure where I heard it from now,…. Here?, Shot Show reviews?, HAM site? or,.. “word on the street is”,…. but I (definitely) know I read it somewhere that JSB was going the screw on lid route.

      I am sure though that there is still plenty of the old inventory out there that must be cleared out first.

      Happy to see it at any rate,……….. Chris


      • Yep, I vaguely remember something about the JSB screw tops. I dumped a tin the other day and wished they had a scew top. They are the best pellets in most of my guns.


  13. Ok,

    I will try to explain my rationale for more pumps especially at longer distances. One thing I have observed is that at longer distances the number of pumps makes more difference in accuracy. I have had good results with 4 or 5 pumps and bad results with 6 or 7 and then the best with 8 or 10 or more pumps depending on the gun and the distance. There are many variables that go into the accuracy equation, we discuss them all the time. Pellets, velocity, pressure strain on the reservoir, harmonics and on and on. One thing on a multi-pump that I think makes a significant difference is that as the number of pumps increases the difference in the pellet velocity decreases. At longer distances especially past 25 yards the difference in velocity with have a larger differnce in the POI and not just in the horizontal drop.

    Here is the velocity verses pumps for todays Blue Streak from part 1 with the velocity differences.

    Crosman Premiers
    pumps………fps……….difference
    3……………..453
    4……………..516………..81
    5……………..557………..41
    6……………..600………..43
    7……………..626………..26
    8……………..651………..25
    9……………..665………..14

    Benjamin Cylindricals
    pumps………fps……….difference
    3……………..456
    4……………..509………..53
    5……………..548………..39
    6……………..560………..12
    7……………..590………..30
    8……………..621………..31
    9……………..634………..13

    Notice that the velocity difference gets smaller with more pumps. With most multi-pumps there is enough dead space on the piston stroke that the velocity with reach a peak with the velocity difference going to near zero. Also in general the velocity differnce with be greater for a series of 4 pumps than it will be for a series of 9 pumps for most guns.

    Below is a chart that shows the valve pressure vs pumps for three different pump dead spaces using the Crosman 101 multi-pump. The dead space is based on an equivalent volume from a length of the pump cylinder. To max out at 400 psi a dead space of 0.285 inches is needed. For 800 psi it is 0.144 inches and for 1200 psi it is 0.095 inches.

    Don


Leave a Reply