Convertibles

Discussion in 'Handguns: Revolvers' started by eddiememphis, Aug 5, 2021.

  1. eddiememphis

    eddiememphis Member

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    I saw a nice '65 Malibu on the highway today...

    Oh wait! Wrong forum.

    I was looking at the Blackhawk .357/.38 that has a 9mm cylinder. Taurus has one as well.

    Since the 9mm is a .355" and the .357/.38 is .357", what is the bore size on these guns? I have looked around and can't seem to find the answer.

    I am guessing they are .3585 or so because stuffing a bigger bullet in a smaller hole is a bad idea.

    Or is it?

    I know there are different optimal clearances for cast and jacketed bullets, but isn't a .355" bullet bouncing down a larger bore going to be inaccurate and waste energy, having a poor seal. Will it engage the rifling properly?

    I likely am overthinking this but it has been bugging me for a couple days.

    Can one size fit all?
     
  2. Pat Riot
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    Pat Riot Contributing Member

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    I do not have a Blackhawk Convertible .357 / 9mm but I am interested in buying one as well.
    A couple of my Cowboy Action Shooting friends have them and they tell me that 9mm is slightly less accurate as .38 and .357 from their revolvers, but I do not recall ever hearing them mention bore diameter. Come to think of it, they didn’t really expand on what “slightly less accurate” was.

    I would like to come across one for sale so I can buy it and find out for myself. ;)
     
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  3. shootstraight57

    shootstraight57 Member

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    I had one years ago and was the Ruger Blackhawk Convertible. .357/.38/9mm. The .357 and .38 shot very accurately but the 9mm was all over the place! I took it as the bullet bouncing around in the barrel before coming out!
     
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  4. fxvr5

    fxvr5 Member

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    The 9mm and 357 mag have the exact same barrel groove diameter specifications; 0.355" + 0.004".

    https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.3-CFP-and-R-Approved-2015-12-14-Posting-Copy.pdf

    I've slugged many barrels and there is no difference between the groove diameter of 9mm and 38/357 barrels, which is consistent with the SAAMI specs.

    I have a Ruger convertible, and there is no difference in accuracy between 38/357 ammo and 9mm ammo; tested with the gun in a Ransom Rest.
     
  5. BoBo522

    BoBo522 Member

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    My New Model Blackhawk convertible shoots equally well with the .357 Magnum cylinder or the 9mm cylinder. YMMV.
     
  6. gpb

    gpb Member

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    I have a Ruger Blackhawk 6.5 inch 357/9mm convertible that I bought new 5 years ago. The only 9mm ammunition that I have shot through it is ammunition loaded to work well in my 9mm pistols. No effort has been made to optimize the loads for the convertible.

    The loads are typically 124 grain .356 FMJs over Unique powder. At 50 feet the convertible groups about 10% larger groups with 9mm than 357 and about 2 inches lower. Other than the shift in point of impact, there is little difference between 357 and 9mm form the convertible. I don't have a chronograph, so I don't know what the velocity difference is.
     
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  7. Bill M.

    Bill M. Member

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    I have a Ruger Blackhawk in .357 and 9 mm. It shoots both rounds pretty accurately. The bore diameter is the same as a .357. The throats of the 9mm cylinder are tapered out and allow the bullet to expand a little before it gets to the bore. Try dropping a .358 jacketed through the cylinder from the front and you will see what I mean without a lot of measuring and theory. While it shoots both cartridges accurately it does not shoot them to the same POI. Like the poster above, my 9mm shoots about 2" low and 1" to the left. My most accurate groups have always been from the .357 cylinder but that might be because I have shot it with a lot of different loads and have not done much experimenting with the 9mm. Since I reload there is little need for the 9mm. I can shoot the same weight and velocity in the .357 or .38 special cases. But...I sorta like loading and shooting the little 9mm shells too. It is a gimmick but it grabbed me.
     
    Last edited: Aug 6, 2021
  8. cfullgraf

    cfullgraf Member

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    I have a Ruger 357 Mag/9mm Blackhawk convertible. I've yet to put any rounds through the 9x19 cylinder, but it is there if I need to. I wanted a 4-5/8" barrel Blackhawk and the convertible was the first that I found.

    I have a S&W Model 986 which shoots 9x19 very accurately so revolvers can shoot semi-auto ammunition well.

    This had been my understanding of 357 Magnum/9x19 barrel bore diameter is the same from some point before the 1980's.
     
    Last edited: Aug 7, 2021
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  9. Tallball

    Tallball Member

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    I have a 357 Blackhawk. I found a 9mm cylinder for it on eBay that happens to work. If there's much difference in accuracy between the 38's I normally shoot and the 9mm's I shoot out of it occasionally, I haven't really noticed.

    I have an SP101 in 9mm also, and it also has "normal accuracy" for a 2.5" SP101.
     
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  10. CajunBass

    CajunBass Member

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    I've never owned one, but from the time I discovered "gun books" and wore out several copies of the "Shooters Bible" I've thought the Ruger Convertible would be the perfect gun for the person who totes a gun all over the world. You almost certainly be able to find some kind of ammo most anywhere in the world. Of course I knew nothing of the legalities of such a thing in the those days, but the idea is still pretty sound I think.
     
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  11. NorthBorder

    NorthBorder Member

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    I still want to hear about the Malibu.
     
  12. Gordon
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    Gordon Contributing Member

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    I have an old three screw convertible 6.5" gun and yes the .38/.357 cylinder is a little more accurate. Not a great deal tho, the bullet jump to throat and forcing cone is a lot longer on the 9mm . Also the rimmed cartridges seem more firmly head spaced . The 9mm cylinder does NOT "throw them all over tho" .
     
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  13. Fyrstyk

    Fyrstyk Member

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    Everyone is talking about the Ruger .357/9mm convertible. I have a Ruger 45ACP/45Long Colt convertible. I really like it cause I can shoot easy to find 45ACP for plinking and save the 45 Long Colt for for more serious back country hiking and hunting. I have made reloads for both that shoot to the same POI at 25 yards, and some heavy loads for the Colt for hunting. Lets not forget that Ruger also made a 10MM/38-40 convertible. Wish I had one of those, but they are hard to find.
     
  14. .455_Hunter

    .455_Hunter Member

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    I have the Vaquero .38-40 / .40 S&W set-up. Very handy to shoot readily available (in "normal" times) .40 180 gr ammo. The POA/POI of both rounds are very similar.
     
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  15. Pat Riot
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    Pat Riot Contributing Member

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    I have a New Vaquero .45 in .45 Colt. The stamp on the frame just says .45, not .45 Colt so I figured I would call Ruger and see about a .45 ACP cylinder. I sent it in and they made me a stainless cylinder for my stainless gun. I do need to do something to differentiate between the .45 Colt and ACP cylinders.

    Here is the gun just after coming back from Ruger.
    ACA93D28-BD0A-45FB-B08A-3F25BF1587C6.jpeg

    A while back I took it to the range to test some .45 Colt loads. I had the .45 ACP cylinder in it…Duh! :confused::rofl:

    The gun actually shoots my .45 ACP loads a little more accurately than my .45 Colt loads. I really like it with both cylinders.
     
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  16. TTv2

    TTv2 Member

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    If we're talking convertibles I'd like to hear about Geo Metros. Can't beat something that get 50 miles to the gallon and cruises just fine at 60 mph.
     
  17. TTv2

    TTv2 Member

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    While the bores for the .38/.357 and 9mms are the same, I'm gonna make a theoretical situation here where we have a .355" 9mm bullet and it is being shot thru a bore with .357" grooves. If that happens the jacketed bullet will grow in size due to heat and pressure and it should fill the grooves, but it won't do that immediately upon contact with the rifling and gases will blow by in the grooves and velocities will not be as consistent. With a hollow base bullet the rear would seal in the grooves immediately and would likely shoot more accurately as they would have a more consistent velocity.

    Still, even with the standard FMJ bullet if it doesn't fill the grooves the lands are still imparting a spin on the bullet, so this theory of a bullet that is .001 or .002 smaller in diameter than the grooves is bouncing or jiggling down the bore is foolish.
     
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  18. Tallball

    Tallball Member

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    I have the 45colt/45acp convertible also. IIRC, the POI for the two calibers is slightly different, but the accuracy seems about the same. I shoot way more 45acp out of it.

    I'd REALLY like to have a 10mm/40 caliber convertible, too, but the chances of me running across one for cheap are pretty near nonexistent.

    I also had a Single Six 22lr/22magnum convertible. After significant experimentation, I didn't find that the 22 magnum had much advantage out of the 5.5" barrel (and it cost a lot more).

    Here's the 45 convertible. I got it NiB. Since then I've bought the rest used; they're sturdy in the first place and difficult to wear out.

     
  19. TTv2

    TTv2 Member

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    Give it time, but I've gone back and forth thinking about a 10mm revolver because I see a lot of lead bullets available for the caliber that don't sell because people are largely loading it to shoot from a semi auto and want plated or jacketed bullets instead.

    What would really get me into a 10mm revolver is if it's chambered for 10mm Magnum. It's everything that .41 Magnum can be and more because it would also shoot .40 and 10mm Auto.
     
  20. Rock185

    Rock185 Member

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    I have some convertibles, .22LR/.22 Mag, .357/9MM, .455 Webley/.45 ACP, .454 Casull/.45ACP, and I guess my 10MM GP100 might be considered a convertible since I could shoot .40 S&W in it.

    Reference the .357/9MM convertibles, I don't think that 9MM bullet is bouncing/rattling down the bore. SAAMI spec. for .38/.357 and 9MM are both .346 bore and .355 groove diameter. I couldn't detect any accuracy difference between .357 and 9MM with my Ruger Blackhawk convertible. My latest .357/9MM convertible is an aftermarket S&W 686 conversion, and I haven't had the conversion cylinder long enough to determine if there is an accuracy difference. With the 686 conversion though, I'm not going to be surprised if the 9MM is less accurate due to the long ~.381" dia. freebore before the projectile reaches the .357" dia. cylinder throats.....

    FWIW, I have used jacketed .357" dia. bullets in 9MM and .38 Super pistols. No catastrophes, or even anything out of the ordinary to report.
    686 (8).JPG
     
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  21. ThomasT

    ThomasT Member

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    I have a 5.5" BH 357/9mm convertible and couldn't tell much difference in accuracy between the two. But I didn't keep it a long time either. I thought the gun was way too big for the rounds it fired. In hind sight I should have kept it. If I bought another BH I would just go with the 357 and forget the 9mm conversion. But I would try to find the 7.5" barrel to get as much velocity as I could out of the round.

    But if I bought a convertible it would be the regular Black Hawk 45 Colt/45 ACP with the alloy grip frame to save a little weight. I would prefer the 5.5" version.
     
  22. ThomasT

    ThomasT Member

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    I had read many years ago that S&W used the same bore dimensions for 9mm and 38/357.

    I thought I was the only one to do that. Good to know someone else has tried it too. I used to load 158gr SWC lead bullets in 9mm cases. They shot fine. I just used enough powder to make sure the gun would cycle reliably.
     
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  23. Driftwood Johnson

    Driftwood Johnson Member

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    Howdy

    This is my 45 Colt/45 ACP Ruger Blackhawk that I bought brand-spanky new in 1975 for $150.

    plZsbaNdj.jpg




    Yup, the frame is simply marked .45 CALIBER. Nothing about 45 Colt or 45 ACP.

    pou3ylz2j.jpg




    $150 was a lot of money for a kid in his twenties in 1975, and I was only interested in shooting it with 45 Colt. I asked the shop owner if I could buy it without the 45 ACP cylinder for a little bit less. He looked at me like the stupid kid I was and told my I had to buy it with both cylinders.

    The truth is, I have always been a revolver guy and it was many years before I fired the 45 ACP cylinder. Still a revolver guy, and still only shoot 45 Colt in it.

    No, the extra cylinder is not for sale.
     
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  24. jstert

    jstert Member

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    i have ruger blackhawk convertibles in both 45lc/acp and 357/38/9. i love them, especially for their ability to shoot any (formerly) cheap as dirt 45acp and 9mm steel case ammo. im not so accurate in any case so i don’t notice any difference shooting the semiauto rounds. just get one or both, no need to overthink it, you wont regret it.
     
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  25. StrawHat

    StrawHat Member

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    My brother did this to help me distinguish between the cylinders.


    30174F4F-995F-4501-8911-DC96449D6688.jpeg

    I made it a lot easier since then. I only shoot the ACP round and have lost the long Colt cylinder!

    Kevin
     
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