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CO2 Crosman 38T Target revolver: Part 8

Crosman 38T Target revolver: Part 8

38T
Crosman 38T.

Part 1
Part 2
Part 3
Grips & tips
Part 4
Resealing the Crosman 38T revolver: Part 5
Part 6
Part 7

History of airguns

This report covers:

  • Pellet test
  • The test
  • Rotate the barrel
  • Next group
  • Discussion
  • The rear sight
  • Rotate the barrel some more
  • What has been learned? Summary

In this report we will learn a lot more about the workings of the Crosman 38T revolver. I tested the .22-caliber 38T that wasn’t shooting very accurately in the Part 7 test. This is the revolver that was resealed by reader 45Bravo, who is Ian McKee. He suggested turning the barrel to see if that would affect accuracy. Today we will see if it did.

Pellet test

This particular 38 T in .22 caliber didn’t really have a favorite pellet. RWS Superdomes were the most accurate, but I decided to something entirely different — based on your answers to my question, “How to test pellets?“. I used a pellet that I didn’t test for accuracy previously in this air pistol — the RWS Hobby wadcutter. In other words, I tested this concept with a pellet whose accuracy I knew nothing about in this air pistol. It was the only pellet I used for the entire test. Doing that helped me a lot with the how I test pellets question — because the question always has to include a test gun, as well.

The test

I shot 5-shot groups from a bench rest at 10 meters. The pistol was hand-held and my hands were rested on the sandbag. I’ll explain why 5 shots and not 6 in a bit. The first target was to establish where the pistol is at the start of the test.

The first 5 pellets landed in a vertical group a little to the right of the centerline. The group measures 2.068-inches between centers. This is approximately how good this pellet is in this gun when shot by me on this day.

38T first group
On the first target five Hobby pellets landed in a group measuring 2.068-inches between centers.

Rotate the barrel

For the first test I disassembled the pistol and rotated the barrel about 30 degrees clockwise as seen while holding the pistol in your shooting hand. Before I rotated the barrel I made a mark on the outside of the barrel to index it.

38T disassembled
One slotted screw and the barrel shroud comes off. One more Allen screw on top of the receiver and the barrel is loose to rotate. It’s a two-minute job, start to finish.

I had thought I would leave the shroud off the barrel after turning it until it dawned on me that the front sight is on the barrel shroud. A front sight is fairly necessary when you want acuracy! So back on it went.

Next group

My next group was interesting. I saw the first shot land low and hit the edge of the bull between 4 and 5 o’clock. The other four pellets went higher on the target with three of them in a nice tight group. That gave me confidence that I was on the right track by rotating the barrel.

The group measures 1.948-inches between centers. The upper 4 shots measure 0.847-inches between centers.

38T first turn
The first turn of the barrel produced this group. It looks as large as the first one, but the last 4 shots are all above the first one. Five pellets in 1.948-inches with the top four in 0.847-inches.

I found it easier to load the pellets this time, after rotating the barrel. They seemed to go into the cylinder much better and without hitting anything. Maybe what Ian said about aligning the cylinder with the barrel is also true.

I shot a second group without changing anything. I wanted to confirm that the previous group was a good one. This time the first shot hit the edge of the bull at 6 o’clock and the other 4 went to 2:30 on the bull. Five shots are in 1.97-inches at 10 meters with the last 4 in 0.541-inches. This is the accuracy I expected to see from this airgun. And it gave me a great idea.

38T first turn group 2
First shot at the bottom and the other 4 are in 0.541-inches. The first shot opens the group to 1.97-inches.

Stock Up on Shooting Gear

Discussion

I had noticed that twice the first shot had hit low on the target. It may have done it on the first group as well, but I didn’t see it that time. What if I loaded five pellets but fired 6 times? The first shot would be a blank that might serve to settle the revolver for the next five shots. Would that tighten them?

I adjusted the rear sight to the left, I thought, and shot a third group with the same barrel rotation. This time all five pellets stayed together, going into a group that measures 1.067-inches between centers. The group didn’t move over to the left as I had thought and I discovered why on the next try.

38T first turn group 3
This is the third group fired since the barrel was turned 30 degrees. This time the rear sight was adjusted to the left, but it didn’t take. These five shots measure 1.067-inches between centers.

The rear sight

Apparently the rear sight was adjusted as far to the left as it wants to go. Turning the screw both ways moves the notch to the right, and the adjustment screw is starting to back out of its hole.

I adjusted it to the left as far as it would go and then I pressed the notch to the left and the notch moved a small amount more. This is as far left as I can get it.

38T first turn group 4
The group didn’t go to the left like I hoped, but five Hobbys are in 1.466-inches, which with this revolver isn’t that bad.

Rotate the barrel some more

I decided to rotate the barrel further in the same direction (clockwise) to see what that would do. So off came the shroud and I rotated the barrel to a total of 180 degrees from the point where it started. Then I put the shroud back on and shot what would be my last group. This one was an eye-opener!

The final five pellets went into 1.338-inches at 10 meters. But look where they hit. They went up and to the left. That tells me the barrel is bored off center or it is bent, and turning the barrel has a noticable effect on accuracy and also the point of impact. At least it does on this one. Ian was right!

38T second turn group
After the barrel was rotated 180 degrees the pellets landed up and to the left. Five Hobbys are in 1.338-inches center-to-center.

What has been learned?

I have learned that rotating the barrel of a Crosman 38T is not just a way to tighten the group. It’s also the way to move the impact point, just as Ian told us.

I have also learned that the .22 caliber version of the 38T is indeed accurate. You just have to be willing to work with it.

Summary

We aren’t done with this series yet. There is still the adjustable mainspring tension to explore. So stay tuned and we will get to it

52 thoughts on “Crosman 38T Target revolver: Part 8”

  1. B.B.,

    Hmm…I wonder if there is an easy way to view the alignment of the cylinder and the breech end of the barrel to ensure consistent alignment?

    Siraniko

  2. BB
    Rotating the barrel reminded me of when you have had pellets clipping the baffles on shrouded or silenced barrels you have tested.

    And I have seen instructions for muzzle brakes and such that say to rotate the brake to eliminate pellet clipping.

    On this pistol is there a chance the pellet my be hitting the outer barrel shroud? Or do you think rotating the barrel is lining the barrel true to the cylinder.

      • Wow, other than the first shot, that second group is a 4 shot screamer.
        With the first shot is dropping low, I wonder if I might have put a little too much moly on the trigger/hammer areas, and that could be slowing the hammer fall a little making the velocity lower.

        And another thought, one of the pellet chambers may be a little off from perfect alignment, if you were using the same 5 chambers every time.

        You could dig out your bore scope and insert it from the muzzle and see if you see any misalignment when the chamber indexes. (A suggestion, do this with no co2 in the gun, in case the hammer falls as you are rotating the cylinder)

        I know it’s a little more work, but it’s a thought.

        Ian..

      • BB
        It would be nice to know what the true cause is.

        The shroud to barrel or the barrel to cylinder alignment.

        We done made it this far. Enquiring minds want to know.

  3. BB,

    I know in a perfect world, this should not be, but I am also aware this is a fallen world. Would you not see a similar affect if you rotated the barrel of any airgun? If a powder burner barrel was capable of being rotated, would you not also see a similar affect?

  4. BB,
    Take the barrel out, fit into lathe, use live end, check with dial meter for run out along length of barrel. and clamp the barrel ( without shroud ) in a vice with a barrel clamp and then test fire at target. Then loosen the clamp and turn the barrel. So you are not disturbing the barrel to frame fit frame at all. Block the barrel clamp up in the vice so it can’t drop at all when loosening it to turn the barrel. If the barrel is out then you should shoot a circle of groups. Fun! Robert. PS Ridge runner you can do this with your powder burners! Spin the whole rifle.

      • GF1,
        Yip, that will do it. The old “roll it on glass” trick.
        So I crashed my motor bike. Bent the forks. Took the fork legs into this amazing machine shop that does bike stuff. Run by two antique chaps. He said $50 if he can bend them without a crease opening up. I ring them back in a day and ask how they are doing he said maybe $30. I walk in the door and pick up my forks legs. He said that’s $15 please. Wow awesome. They were from another era. They could do anything. Built up cranks? No problem. : – ) Robert.

          • GF1,
            The things people do to perfectly good cranks…. I am pretty sure those two old men could do anything to an engine. They sold me Triumph Trident rings that fitted perfectly in my Honda 360. They mic’d my pistons and came back with two packets and said here you go. Hepolite if I recall. Just great guys. : – ) Robert.

        • RobertA
          You don’t find many people now days that know that stuff.

          All I know is I would make them my best friends for life. To me it’s a lucky day to know people like that.

          • GF1,
            Yes special people indeed. Packed with interesting and useful knowledge. We need more of them! I like to help my friends out and they know they can come to me for advice or my tool box. Rescued a few friends now. Heh there was that time with the “broken” injector plugs…. : – ) Robert.

  5. Just out of curiosity I rotated the barrel on one of my Xisico XSP 120Ds to try to get the rear sight a little more on center. It worked on that one too.

  6. Wow! I had a very difficult time accessing the latest blog this morning. First, a new blog for May 10 did not appear to be available. I clicked on the latest blog shown, May 6, and then the May 7 blog showed on the list. I clicked on May 7 and then today’s blog, May 10, appeared and I was able to access it. I read through the blog and there didn’t appear to be any comments. I clicked on “login” so I could make a reply. The login appeared to be successful but when I went back to blog to make a reply, it still showed that I needed to login. No comments were visible at that time. Finally, at about 11:15 AM, the login succeeded and the comments finally appeared. Whew, what an ordeal. This seems to be getting worse, instead of better. If this does not improve soon, I am afraid people will stop reading and commented on the Pyramyd AIR blog! The people working on this appear to be incompetent. I am getting discouraged by it myself. 🙁

  7. BB

    I have a CO2 popular priced 10 meter beginner rifle. Direct placement on a rest gave most consistent accuracy for this rifle. I was getting vertical stringing at 25 yards. I rotated the rifle 90 degrees on the rest and got horizontal stringing. I don’t know if this relates to your report today or not but it did tell me that my sights were not causing the stringing.

    Deck

      • BB

        Since rotating my rifle 90 degrees on the rest eliminated vertical stringing this also ruled out another variable. Pellet drop at 25 yards for a 10 meter rifle was not causing vertical stringing on my rifle.

        Deck

        • Deck,

          That is pretty wild. I would have to say it is somehow related to the rifling at the muzzle or possibly the crown itself. I would very closely inspect those.

          It sounds as if the pellet is being allowed to tip ever so slightly along a certain axis. Once again this is pure speculation on my part, but it could even possibly be at the breech.

          I don’t know.

    • Decksniper,

      That’s EASY! Barrel harmonics!
      If it isn’t I’ll eat one of B.B.’s hats ;^)
      Seriously give this a try: hang a fairly light weight (no more than 2-3 oz) on a wide cloth ribbon, rubber band, or other non-marring movable along the barrel method. Should change that group and IF (when) you find one of the nodes it will tighten up that stringing; if not eliminate it completely.

      Let us know if i get to eat one of B.B.’s hats, LOL!

      shootski

    • Fish,

      It does seem that it is currently an Ebb Tide for PA IT!

      I got on the water at Slackwater (between a Flood and an Ebb Tide this morning at 0530 (First Light: the end of Nautical Twilight and the Start of Civil Twilight) with sustained NNW 18 Knot winds and frequent gusts to 28 Knots. The river course for 30 Nautical miles is mostly North-South so the wind waves were running 2 to 3 feet…great Down Winder conditions. I had my wife drop me off at the Put-In and then meet me at the Take-Out for breakfast at 0930. I was already out of my Drysuit and had a table for my 2nd breakfast with my wonderful wife. So what does that have to do with the Blog IT issues?
      There are usually two tides a day in most places an Ebb and a Flood let us hope IT has enough fingers to keep plugging all the holes…cause the Flood tide is on the way.

      shootski

  8. B.B.,
    The good news is that my .177 Marauder is holding air nicely now. The other good news is I got the plate over the trigger housing off at last. It saddens me to be replacing a second broken trigger blade. I know that I have treated this rifle with care, and in no way mistreated it. Yet, to add insult to injury, I find the sear has broken. I am tempted to order the replacements that are advertised as being of better material. I will order more sears and blades, regardless.
    Until then, I will shoot the .25 some. Also, I have tins of .22 H&N hp slugs and Norma FT domes (not heavy) to try out with the Origin.

    Hug the cats for me.
    ~ken

  9. Hey Folks! I was a wondering if any of you guys have a couple of 4-40 screws that would be suitable for using on my Maximus trigger assembly. So far the only thing I have found is I can get the screws and spring if I order a trigger kit or I order fifty of the screws. The bad part is I do not want the brass trigger. I do not know what to do with the other forty-eight screws either.

    • RR,

      I replied to your last request. I have 1/4″ and 1/2″ and one 3/4″. I forgot what I used now. I don’t really want to get back in it. ((Look up your last post for more info..))

      I think you have my e-mail. If not, GF1 does.

      Chris

    • RR
      Do you have a hobby shop by you.

      They should have the set screws or allen bolts you need. Allen bolts should work too if I remember right. You just need to get the right length so the head is not sticking out too far to clear the stock when you put it on.

      If so just clear the stock out with a dremel tool for the heads to clear the stock.

    • That’s a pretty common screw size. You should be able to get one at your local hardware store. I know our local True Value hardware has just about every screw you could imagine. Except I did have to order some online for my Gamo Urban’s trigger. I needed 2.5mm x 10mm long and the hardware only had socket head screws that were 12mm long.

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