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  1. #1
    ShooterX is offline Junior Member
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    1911 45 ACP case length & headspace questions

    Sorry for the length of this post... I'm having a little trouble understanding the relationship between a 1911's headspace and its ideal case length for match grade handloads. Am loading for a Les Baer Custom 1911.

    I saw a graphic on another post yesterday but can't find it today. It showed a drawing of four 1911 45 ACP barrels with cases inserted and captions indicating if case length was too long, too little or somewhere inbetween.

    For Bullseye match shooting I've just started making up some test loads for its 45 ACP cartridge with charges ranging from 4.2 gr. up to 4.6 gr. of WST powder with a Dardas 200 gr. LSWC bullet. Have tested functionality with case lengths of .889" and .892" with cartridge OAL of 1.235" on both. Hornady manual and Lyman Cast Bullet Handbook both say to trim cases to .888, while the Speer Manual states .893". After taper crimp my case mouth diameter is .472", which is based on the Mike Venturino calculation that's stated in the Lyman Cast Bullet Handbook (i.e. which in my case for my .451 bullets and casings is comes out to bullet dia. + case rim thickness = .476 -.004 = what should be an appropriate taper crimp dia. of .472.

    Both case lengths feed and extract without fault. Completed cartridges with cases trimmed to .892 drop easily into chamber and casehead sits flush with the little milled extension coming off the back edge of barrel that the bolt face contacts (sorry but I don't know what that part of the barrel is called).

    With a .892" case length, the bearing surface of the LSWC bullet is barely exposed past the case mouth. With .889 it's marginally more.

    Based on the above, all would appear well and good. However, used my caliper to measure depth of chamber from the top of the little milled extension coming off the back edge of the barrel where to the bolt face contacts all the way down to the little lip inside the chamber that the case mouth is supposed to headspace against and get a measurement of .900".

    So my question is that if that headspace lip down inside the barrel chamber is .900" deep and my case length is .892", then shouldn't the case head be .008" below the little milled extension coming off the back edge of barrel that the bolt face contacts? If so, shouldn't a cartridge with a .892" case length drop farther down into the barrel than what I've described?

    Another question is that if the 45 ACP headspaces on the case mouth, and the max. case length for this cartridge is .898", then why would the Hornady manual want you to trim the case to .888", thereby leaving a full .010" gap between the case head and the bolt face, because won't this excess headspace effect accuracy?

    Thanks for any help anyone can provide.

  2. #2
    Steve M1911A1's Avatar
    Steve M1911A1 is online now Senior Member
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    I am a practical shooter, not of the bullseye persuasion, but I've loaded and shot a whole lot of .45 ACP ammunition.

    First, the "little milled extension coming off the back edge of barrel that the bolt face contacts" is called the barrel hood.
    Please don't confuse it with Robin Hood, or even Little Red... Well, you get the idea.

    Second, the .45 ACP case is supposed to headspace on the cartridge mouth, and it does, but if you make the cartridge quite a bit too short, it will still work properly. This is because the 1911 pistol features "controlled feed." That is, the cartridge being stripped out of the magazine slides up the slide's breechface and under the extractor claw long before it ever fully chambers. If the cartridge is too short, it will actually "headspace" on the extractor claw! The extractor will hold it in its proper position as you prepare to fire it.

    Third, bullet-seating depth is a function of reliable feeding from the magazine, as well as cartridge length. As you have surmised, case length is more important, in terms of function. (Accuracy is another thing entirely.) But a cartridge loaded so that the bullet impinges upon the rifling at the barrel's throat may be too long to feed reliably, or, for that matter, to even enter the magazine at all. So overall cartridge length is also functionally quite important.

    Fourth, if your loaded and taper-crimped cartridges drop down into the chamber of their own weight, when the barrel is held at less than vertical, that is absolutely correct. If the rearmost flat surface of the cartridge's head is right at, or ever so slightly below, the end of the barrel hood, that, too, is correct. Chamber length will vary, from barrel to barrel. The trim-to dimensions given are supposed to assure that the cartridges will fit any .45 ACP barrel. The difference between a trim-to length of 0.888" and one of 0.893" is only five thousandths of an inch, so either one will work, probably in any barrel. (I have never had to trim a .45 case, even after repeated reloadings, since they are grossly understressed, and do not stretch.)

    Last, the .45 ACP cartridge is extremely forgiving. Even if shooting bullseye competition, case- and cartridge-length are not things to obsess over, as long as both are within the normally-accepted plus-and-minus limits. As long as your cases and bullets are consistent, and your powder is measured accurately, you will be OK. Consistency is the most important aspect of loading for accuracy.

  3. #3
    DJ Niner's Avatar
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    I would add, to Steve's excellent info presented above, the following:

    - If you are taper-crimping and seating in one step, it is possible/probable that you are getting a tiny "ridge" of bullet material just in front of the case mouth. This is a result of the bullet still being pressed slightly deeper into the case during a single-step taper-crimping process. For this reason, many/most taper-crimp dies are standalone dies; it is recommended that you seat the bullet at one station, and taper crimp with a separate die at the next station. A similar ridge of bullet material or bullet lube can also be caused by insufficient case mouth flaring (case scrapes the bullet during seating, rolling-up some lead/jacket/lube at the front edge of the case mouth), or inserting the bullet slightly crooked into the case mouth prior to seating. In either of the above situations, the round will headspace off the ridge of material in front of the case mouth, instead of the case mouth itself, giving you a false reading when you measure the depth of the round in the chamber at the barrel hood. Unless the ridge is large, rounds with minor versions of this defect will often feed/chamber/lock/fire normally.

    - While I am not familiar with the exact bullet you are using, with some short SWC bullets, there is a condition similar to the one above that can be caused by a full-diameter portion of the bullet extending forward from the case mouth, and actually touching the rifling when the round is chambered (which again, will give you a false depth reading at the barrel hood). Because of the short nose and overall length of these bullets, they will often feed out of the magazine just fine, even if they are seated "long" in relation to the rifling. After you drop a test round into your barrel, invert the barrel, and see if it will drop OUT again from its own weight. If it sticks, check the bullet for any telltale marks which might indicate interference with the rifling, and adjust your bullet seating depth accordingly to eliminate it, if necessary.
    "Placement is power" -- seen in an article by Stephen A. Camp
    (RIP, Mr. Camp; you will be remembered, and missed)

  4. #4
    rex
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    Don't bother trimming 45 cases,they don't stretch like rifles as Steve said and over time they will actually shrink a few thou.Make your loads to sit flush or a hair under the hood and you'll be just fine.What's going to dictate your accuracy is the barrel and fitting,which should be good,and your repeatability making every round as identicle as possible.No mixed cases,accurate powder throws,etc.I'm suprised the .472 is just fine in the Baer,.470 is generally the standard and your extra 2 has been tight in other barrels.But if she works,she works.

  5. #5
    ShooterX is offline Junior Member
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    Steve -Thanks for the great information. You've helped to clear up my initial confusion. Didn't realize that short cases would headspace off the extractor but it makes perfect sense the way you've explained it.

    DJ - Thanks for the additional info. I'm definitely crimping in a separate step. Am concerned though that the bullet may not be seating exactly straight. The face of the only SWC seating stem RCBS makes for its 45 ACP seater die is too large to grip the ogive of these 200 gr. LSWC bullets I'm using. It's made for the larger ogive of the heavier LSWC bullets. To seat these bullets, the flat face of this stem therefore presses down on their flat meplat. This, I'm told could cause the bullets not to be seated straight into the case. The SWC seating stem for my Hornady 9mm seating die fits well on the ogive of these .45 LSWC's. I'm going to find out if the RCBS 9mm SWC seating stem also fits its ogive well and if it does and its thread size is the same as the RCBS 45 cal. SWC stem, then I'll use one of them. Otherwise will buy a Lyman seating die since it does come with a SWC stem that will fit the ogive of these bullets.

    Quote Originally Posted by rex View Post
    Don't bother trimming 45 cases,they don't stretch like rifles as Steve said and over time they will actually shrink a few thou.Make your loads to sit flush or a hair under the hood and you'll be just fine.What's going to dictate your accuracy is the barrel and fitting,which should be good,and your repeatability making every round as identicle as possible.No mixed cases,accurate powder throws,etc.I'm suprised the .472 is just fine in the Baer,.470 is generally the standard and your extra 2 has been tight in other barrels.But if she works,she works.
    Thanks Rex. Right now I'm guess that the .472 crimp diameter is preventing the round from dropping fully into the chamber so the case mouth can seat against the chamber's headspace ridge (sorry but I don't know what else to call the little ridge or lip in the bottom of the chamber that the case mouth is supposed to headspace against). Otherwise, this case that I trimmed to .892 should drop down a little below the barrel hood instead of sitting flush with the top of the barrel hood. I'll try adding a little more crimp to reduce it to .470 to see if that resolves this.


    ALL - I have three more questions:


    (1) when seating these LSWC's, how much of the bullet's bearing surface should extend above the case mouth rim? With these test loads having a COAL of 1.235" there's only a little less than about 1/16" of the bullet's bearing surface extending past the case mouth; and

    (2) the case lengths of this new ("KFA" Head stamped) brass I'm using varies a little. Most are in the .892 to .8935 range, though I've found a few as short as .889 and as long as .8945, though these are more of an exception. How much case length tolerance can I have before having to adjust my taper crimp die? When looking through the jaws of my calipers when they're opened up to .004" gives the impression that using this distance for a crimping tolerance would have a negligible effect on the taper crimp. True, False, Maybe???

    (3) does new .45 ACP normally come trimmed in lengths greater than the lengths I reference in question no. 2? (e.g. lengths as long as the 45 ACP maximum case length of .898".)

    Thanks!!!

    p.s. Here's the graphic I was referring to in my initial post:


  6. #6
    Steve M1911A1's Avatar
    Steve M1911A1 is online now Senior Member
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    1. About seating lead SWC bullets... I've always used 200gr SWC lead bullets thrown commercially from Hensley & Gibbs #68 molds. (H&G is long gone, but there are other commercially-made lead SWC bullets which very closely approximate this shape.)
    If your RN-style seating die is correctly set, the exact same setting of the exact same (RN) seating stem will seat the H&G-style, LSWC bullets correctly.
    I suggest setting the seating die by trial-and-error, using both my and DJNiner's length criteria, always checking that the final seated-and-crimped combination feeds reliably through your magazines. That should be quite good enough. (Do not obsess over caliper measurements. The .45 is forgiving.)
    Then make-up primerless, powderless dummy cartridges for both bullets, tightly taper-crimped, for re-setting the dies in case something gets moved accidentally.

    2. If you want to obsess about case length, pick a longish figure that's within the normal range but shorter than your cases at hand, trim to that, and then forget the entire subject. Any taper-crimp die you can buy will not over-crimp, as long as your cases are not longer than the accepted tolerance.

    3. Each case and cartridge manufacturer has his own set of tolerances. Instead, pick one reloading handbook's figures, and just stick to that.

    I have always preferentially used once-fired G.I. cases, purchased by the thousand. But, after every match there was always a shell-pick-up scramble, and I ended up with an amazing assortment of used cases—at one point even including a large amount of WW2, G.I. steel cases!
    I have never weighed cases, or even measured for case length. I just used 'em newly cleaned, right out of the tumbler. Of course, these "battlefield pick-ups" were used only for practice ammunition, but none have ever failed me.
    Match ammunition was invariably loaded into clean, once-fired G.I. cases. Then, each loaded case was given the "drop-in, slide-out test," and given a visual and tactile check for length against the barrel's hood (barrel out of the gun, of course).

    As I've previously written, I am not a bullseye shooter, though.

  7. #7
    DJ Niner's Avatar
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    As for seating stems, I always used a flat-nosed stem for flat-nosed bullets, with the understanding that as long as I got the bullets CLOSE to sitting square in the case mouth, and there was sufficient flare on the mouth, the flat-nose stem would correct minor tilt at the very beginning of the seating process, allowing the bullet to "float" or slide slightly side-to-side on the stem until it self-centered, while the flat-nose on the stem kept it going straight into the case. If this does NOT happen, you will get a rolled ridge of lead on one side as the case mouth scrapes the bullet, OR, an off-center flat spot on the bullet nose (usually you'll get both, which makes weeding-out rounds that are less-than-perfect rather easy). The flat-nosed stem made for a more consistent seating depth, and is easier to keep clean (if bullet lube builds-up on any seating stem, your bullet depth will vary, and the hollow type of fitted-to-the-ogive stems seemed more susceptible to lube-build-up-related seating-depth problems, in my experience).

    ALL - I have three more questions:

    (1) when seating these LSWC's, how much of the bullet's bearing surface should extend above the case mouth rim? With these test loads having a COAL of 1.235" there's only a little less than about 1/16" of the bullet's bearing surface extending past the case mouth;
    There is really no numerical answer to this question; it all depends on your pistol's chamber/barrel. If you're worried about having too little material in front of the case mouth to secure the crimp, you really don't have to; remember, as target-shooting ammo, these cartridges will never be chambered over-and-over-again like some self-defense cartridges. They only have to withstand the trip up the ramp once, so unless you are getting indications that the bullets are being pushed back into the case during feeding/chambering, you can safely use other criteria to determine seating depth. Side note: Most serious bullseye shooters I knew would never re-chamber a round during a match. If they had a stoppage/alibi or other need to re-fire, they'd eject the previously chambered round out onto the ground, and get a new round to replace it in the mag. Ejected rounds were visually inspected for defects like dents and deep-seated bullets, then added to the "practice box" of ammo.

    Just make sure that:

    - The COAL is not exceeding the max COAL, or you may have feeding difficulties coming out of the magazine.

    - The bullet depth is getting you one of the two center outcomes in the graphic shown above (#2 or #3). I preferred the normal headspace option, as I would often shoot much more ammo per session than other shooters, and once the pistol gets really dirty, ammo loaded using the third option may fail to chamber due to slower slide velocities, crud/powder granules in the chamber, or simple lead build-up. I'd personally rather have slightly-less-accurate but more reliable ammo.

    - You have SOME amount of bullet projecting from the case mouth to crimp into.


    (2) the case lengths of this new ("KFA" Head stamped) brass I'm using varies a little. Most are in the .892 to .8935 range, though I've found a few as short as .889 and as long as .8945, though these are more of an exception. How much case length tolerance can I have before having to adjust my taper crimp die? When looking through the jaws of my calipers when they're opened up to .004" gives the impression that using this distance for a crimping tolerance would have a negligible effect on the taper crimp. True, False, Maybe???
    I agree with Steve; it shouldn't be a factor at all. Personally, I used to sort my batches of cases into three piles: near-nominal (for that batch), short, and long. Near-nominal was used for serious purposes, short and long were practice ammo. Even so, there was very little difference in their actual performance, most of which was pre-determined by how well I was "driving the gun" on any given day.

    (3) does new .45 ACP normally come trimmed in lengths greater than the lengths I reference in question no. 2? (e.g. lengths as long as the 45 ACP maximum case length of .898".)
    I don't think I ever bought or loaded new cases for any of my .45 ACP handguns. I knew so many other .45 shooters, and pick-up brass was so common at the local outdoor/public ranges, that I don't remember ever buying new .45 cases. Not even once.
    "Placement is power" -- seen in an article by Stephen A. Camp
    (RIP, Mr. Camp; you will be remembered, and missed)

  8. #8
    rex
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    1. That sounds good,roughly a fingernail thickness is all that's needed.I was running H&G copies like mentioned and my OAL was .001 shorter than yours and never had a problem.

    3.Haha,I don't know,I've never found one at max length though.

    2.That length range isn't bad.I don't shoot bullseye so I never worried,but I'll throw this at you.

    Consistancy is paramount to ultimate accuracy-powder volume,leftover space volume,bullet consistancy,case consistancy,bullet pull and bullet jump into the rifling (this is through the leade which is the unrifled and tapered area from the headspace band to the rifling).Bullet pull is where I'm going.Different cases have different thicknesses,Remington is thin walles and Federal and Starline are thick.Using mixed brass,you will get varied case tension on the bullet,thinner will have less tension so the bullet will release easier,causing less buit pressure and lower velocity on thet round.Case length does the same thing to a point,longer can grab a touch harder if you get down under a .470 mouth diameter (roughly).Mixed brass and length together maximize the difference in pull,giving you a higher deviation in velocity than the powder normally has,which is compounder by the volume or weight deviation of the powder charge.Are you freaking yet?Haha.

    What I'm getting at is since you're shooting bullseye,you're out to 50yds.If you are doing your part and need to tighten up groups with your existing load,pick the shortest case of your batch or the shortest in the average range and trim to that like the guys said,you have consistand tension and pressure on bullet pull now.Whatever your velocity deviation is now is solely the choice of powder and throw variations.Also,whenever you buy a new batch of brass,run them through the sizing die because they are not pre sized new,there as they come out after being drawn and vary in diameter.They will work fine if you don't,but they are inconsistant until you reload them the first time.

    I'm not familiar with WST,but if it just doesn't seem to pull around the accuracy you want try something else.Joe Chambers builds 1911s that are freakin' awesome,he has printed under an inch group at 50yds and his guns hover right at 1" consistantly.He uses a 185gr swc I believe,but if you go to his website I think the load is mentioned there.I don't remember the powder he uses but it's known to be very consistant,giving a low velocity extreme spread.

    Gotta go for now,later man.

  9. #9
    TOF's Avatar
    TOF
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    You have been given excellent info to this point. I just want to comment on "New" vs "Used" Brass.

    I typically purchase brass once fired in single headstamp 1000 piece lots. I have never had problems with once fired brass.

    A few years back I purchased a Gp100 and although it is a .357, I wanted to shoot .38 load levels but didn't want the ring around the collar left by .38 cases in a .357 chamber. I therefore purchased 1000 new Winchester .357 Mag cases so I could load to reduced power levels using full length cases.

    After a quick length measurement with calipers on one or two cases I decided they were within max length and ended up loading several samples. Upon inspection of the loaded rounds I determined all case mouths were cut on an angle yielding up to .015 inch taper side to side in case length. Needless to say I was upset but ended up trimming all to a common length. The length had to be .025 below Max to make all equal.

    I have never found comparable error in factory loaded cases and believe that was a way for Winchester to dispose of a reject lot which was unsuitable for their loaded ammunition line.

    I will no longer purchase new pistol cases if at all avoidable.

  10. #10
    ShooterX is offline Junior Member
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    Thanks everyone for all of this great info! I'm going to put all of this to good use. BTW, my gun club has a Ransom Rest and some chrony's available for members to use at their leisure. I think what I might do sometime once it warms up is to make up some test batches of different COALs (provided they fit in the mag and will chamber in the barrel) and different powder charges to try to figure which COAL and powder charge this 1911 likes best.

  11. #11
    DJ Niner's Avatar
    DJ Niner is offline HGF Forum Moderator
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    An excellent idea, and your club has some very nice options!

    Sure beats my old accuracy-test setup; a wobbly card table, a lawn chair, and a rolled-up scrap of leftover carpet...
    "Placement is power" -- seen in an article by Stephen A. Camp
    (RIP, Mr. Camp; you will be remembered, and missed)

  12. #12
    Steve M1911A1's Avatar
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    ...You get a chair? And carpet?

  13. #13
    DJ Niner's Avatar
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    Had to have'em; ground was too lumpy too get any lower and still see the target.

    'Twas all dirt and rocks back then; nothing had begun to grow yet, as the Earth was still cooling...
    "Placement is power" -- seen in an article by Stephen A. Camp
    (RIP, Mr. Camp; you will be remembered, and missed)

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