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Thread: 250+ grain in 45acp

  1. #1
    Boolit Master
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    250+ grain in 45acp

    Ok, so I have a question about my BH convertible. I am going to be loading up some trials for the acp cylinder soon. I had some decent luck with the 255 in my colt cases with right around 6 grains of Unique. Very light load. So is there some reason I am not seeing that I cannot put the same load into the acp cases?

    The reason I ask is first off I know the acp cases are rated at a higher pressure than the colt. 20,000 versus 14,000 give or take. So I would think it would be fine. But then I pull out some load data and of course I cannot find any for the 255 grain boolits I want, but for 230 grain cast lead the max charge is listed as 5.5 or so grains of Unique.

    I know that as you go up in boolit weight you generally drop in powder charge, so that would mean that 6 grains of Unique would seemingly be way above what the "trend" is.

    So what gives? Is there something I am not considering here? It the same gun, just different cylinders. Same boolit, same powder, just different case. But the acp case is rated for higher pressures. Would the same powder, primer, and boolit produce a different amount of pressure in another case with it being of the same diameter? The only thing I can see different is the amount of air space, but usually more airspace lends itself to more pressure correct?

    Thanks for the help.

  2. #2
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    Larry Gibson's Avatar
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    SAAMI MAP for the 45 Colt at 14,000 psi is in deference to the older revolvers made for black powder. The 45 ACP was designed when much better steels were in use and smokeless powder was used. Thus it's MAP is 20,000 psi. You will be fine with 6 gr Unique under the 250 gr cast bullet for use in your Ruger. However, instead of just jumping to a load why don't you "work up" the load by starting at 5 gr and then 5.5 and the 5.8 and then 6 and see how they group?

    Larry Gibson

  3. #3
    Boolit Bub
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    Case volume is less with the 45 acp, yes? That ought to change pressure some.

  4. #4
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    Quote Originally Posted by Larry Gibson View Post
    SAAMI MAP for the 45 Colt at 14,000 psi is in deference to the older revolvers made for black powder. The 45 ACP was designed when much better steels were in use and smokeless powder was used. Thus it's MAP is 20,000 psi. You will be fine with 6 gr Unique under the 250 gr cast bullet for use in your Ruger. However, instead of just jumping to a load why don't you "work up" the load by starting at 5 gr and then 5.5 and the 5.8 and then 6 and see how they group?

    Larry Gibson
    I would not mind doing that. And I probably will play around some. I just have tried the 6 grain load with the same boolit out of the same gun, just with the different cylinder, and found it to be a very nice load.

    I know that the case is shorter, and the throats on the cylinder are going to be longer, but I was thinking I might get close to the same results with the acp as I got with the colt.

  5. #5
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    Quote Originally Posted by newton View Post
    The only thing I can see different is the amount of air space, but usually more airspace lends itself to more pressure correct?
    Exactly the opposite effect, if all other factors remain constant.
    "The best argument against democracy is a five-minute conversation with the average voter."--Winston Churchill

  6. #6
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    Quote Originally Posted by dvnv View Post
    Case volume is less with the 45 acp, yes? That ought to change pressure some.
    Yea, but I would think it would help with the pressure rather than make it worse. Maybe my thinking is backwards on this. In other words, with the same amount of powder and the same weight of boolit, a case that has more "room" in it will have a greater amount of pressure than one with less room in it. I thought this is one of the theory's behind fillers and such.

    That is my thoughts, not fact. I am hoping that I could get someone to lend me some understanding about the known facts of this theory of mine.

  7. #7
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    Quote Originally Posted by 9.3X62AL View Post
    Exactly the opposite effect, if all other factors remain constant.
    Ah, well then that answers my question.

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    So maybe I will start at 5, and work my way up after all. haha.

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    Ok, so now things are starting to click in my head the right way maybe. The reason why seating a boolit deeper increases pressure is because you are reducing the amount of 'air space'. So along with that seating the boolit further out can reduce pressure a little bit.

    It all makes more sense now. So even if its the same charge, same weight boolit, the fact that there is less room means that while it might be around 8,000psi in the colt, the acp might see a whole lot more.

    I wonder if there is a conversion factor based upon the percentage of airspace removed? For instance if I was just referring to one cartridge and I wanted to know how much pressure could be increased, or decreased, by the position of the boolit inside of it.

  10. #10
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    Awright, sir!

    I'm sure there are formulae "out there" somewhere that can approximate and predict the general behavior of powder amounts in given airspace situations. The Powley Computer and the computer pressure modeling software (e.g., Quicload et al) can do a fair job at these estimations, but these don't/can't factor in your firearm's variables--so you're back to load work-ups, even with the whiz-bang formulae.

    You have one advantage going for you--the Ruger Blackhawk is a robust revolver design, whether using the 45 Colt cylinder or the 45 ACP "wheel". You have a built-in margin of error, in other words. THAT DOES NOT EQUATE TO LICENSE TO GO NUTS WITH PRESSURES--it means that you'll remain safe if you inadvertantly venture into over-spec pressures.
    "The best argument against democracy is a five-minute conversation with the average voter."--Winston Churchill

  11. #11
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    I never have in the past 'worked up to' high pressures. I always try to stay well below. However, I have always only worked with rifles. But it is nice to have the BH with its strengthened frame design.

    I have gotten to high pressures even with below max loads. I always have understood this to be first seen in flattened primers. Is this the same with pistols and revolvers? Or is there other things to look for?

  12. #12
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    One other thing to consider is what 250 gr bullet you will use. If it is a SWC all of the bullet up to the front edge of the shoulder will have to be in the .45 acp case or it won't chamber in the acp cylinder. At least that is the way my Lipsey's .45 convertible is chambered. That might run pressures up pretty quick!
    "The ultimate result of shielding men from the effects of folly is to fill the world with fools."
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  13. #13
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    The Lee 255 grain RF would be a better choice if you wanted to shoot a heavier slug in the 45 acp.
    If you look at the load data in the Speer #12 manual on their 260 grain hp, (average .680 long) loaded to a COL of 1.200, and then load Lee 255 RF (average .600 long) to the same COL, there is approximately .080 more case capacity with the Lee boolit.
    You will have no problems with pressure if you stay with the 1.200 COL in the acp case.
    I have worked up a good load for my Taurus PT1911 and this boolit combination. You should have nary a problem with yourf BH convertable.

    Jack
    Last edited by littlejack; 04-25-2012 at 04:10 PM.

  14. #14
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    Actually the lee 255 is what I am shooting. I just titled it "250+" because most load data is for 240 grain and under. I do not have that many load books yet so I am just going off what I know and have available.

    Its what was shooting good from my colt cylinder at that given charge. I'll play around with OAL and see what I can get away with.

  15. #15
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    I ust shot some 250 lswc bullets loaded over 6.5 Unique in .45 ACP cases from a Cimmaron convertible. No pressure signs, but I'm thinking of backing off to 6.0 grains. That load will SHOOT, though. Any thoughts?


    Forgot to mention, OAL was 1.19"
    Last edited by scattershot; 04-29-2012 at 10:40 PM. Reason: Added info
    "Experience is a series of non-fatal mistakes"

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    Pretty simple but possibly stupid question. IF you already have the LC cylinder why are you trying to push the ACP?

  17. #17
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    Quote Originally Posted by dmize View Post
    Pretty simple but possibly stupid question. IF you already have the LC cylinder why are you trying to push the ACP?
    Fair enough question. I am not trying to push it actually. My thoughts were that it would be a whole lot lighter load. When I originally asked the question I was thinking backwards on how the load reacts. The load I was looking at is a light load in the LC. So I am really not looking to push it at all. I want a light plinking load. What I would like to do is duplicate the light load I shot in the LC which is around 600 fps.

    I'm going to hopefully shoot some later today. I am going to put in 5 grains to see if that gets me where I want. Maybe it will have to take less. I wonder if a 4.5 load would come closer to the light load I'm looking for?

  18. #18
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    For me, it was an experiment. I have gotten heavy bullets to feed in one of my ACPs, but these won't. Also, I have a wheelbarrow full of ACP brass, not so much Colt.
    "Experience is a series of non-fatal mistakes"

  19. #19
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    Quote Originally Posted by scattershot View Post
    For me, it was an experiment. I have gotten heavy bullets to feed in one of my ACPs, but these won't. Also, I have a wheelbarrow full of ACP brass, not so much Colt.
    This is another consideration for me too. I found a place I can get once fired for a whole lot cheaper than the colt.

  20. #20
    Boolit Master
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    What you want to do can be done, but there are some considerations to doing so;

    1. You will have to taper crimp the bullet on a cylinderical part of the bullet, as a roll crimp in the groove won't allow the case to headspace on the case mouth.

    2. In a Smith and Wesson DA sixgun you can crimp in the groove because the clip or an AR case will provide headspace.

    3. In the Ruger SA, you will have to seat the bullet way deep in the case, reducing to a considerable degree the powder capacity, with will increase pressure considerable with the same powder charge. So the powder charge must be reduced.

    4. The Ruger SA cylinder in 45 ACP is a little fussy about what size bullet it will allow into the throat and any full diameter portion of the bullet sticking out of the case will have to enter the throat. They don't have a tapered throat, so sizing diameter will be determined, by what will enter the throat with ease. Even if the throats are .4525, it may take a .451 bullet to drop into the cylinder with ease.

    Bottom line...It isn't worth the effort for what little can be gained. There are good 200 - 230 grain bullets out there that can be loaded in the ACP case that will function and shoot very well in your Ruger SA sixguns.

    The Ruger SA shoot very well with the ACP cylinder and round, BUT you are not going to get 45 Colt performance from the ACP case, so accept that fact and have fun.
    Disclaimer: The above is not holy writ. It is just my opinion based on my experience and knowledge. Your mileage may vary.

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BR Bench Rest M Magnum RN Round Nose
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