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Thread: Pistol bullet seating depth!

  1. #1

    Default Pistol bullet seating depth!

    Though I have loaded ammo for 30+ years very little of it was pistol ammo, mostly rifle and revolver. I am being told that it can be unsafe to seat a pistol bullet 1/8" deeper than spec.. Is it and if so why?

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    Member Dan in Alaska's Avatar
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    Seating bullets deeper than spec reduces the initial case volume and increases pressure. Because pistol cartridges have smaller case volumes and use much faster burning propellents, than rifle cartridges, a person can run into pressure troubles quickly with seemingly minor changes in bullet seating depth.

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    It can increase pressures dramaticly. The case volume is very small on some cases, (mm, 45ac9 40s&w etc) seating the bullet 1/8" deeper can reduce case volume 20/30% very easily. The initial case volume compared to the amount expanded gasses (burnt powder) is what determines pressure. The less the initial volume the greater the pressure and it's not a direct relation as the pressure will raise exponentially. Seat bullets deeper in small steps watching pressure carefully as you go.

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    Thanks guys! I guess your never to old to learn something new.

    I have always bought pistol ammo in the bulk and left the empties lay for the range hounds to scarf. I guess its just a matter of never dealing with it until now!

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    Well the good thing is pistol is much easier to load than rifle, you won’t have any trouble. I'm thinking you are loading 45 Colt and depth is not going to be an issue on them till you get to very heavy bullets with hot loads under them. Even then stick at or over the book OAL for the load and you will be fine.

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    Default Bullet depth numbers ?

    This may sound crazy to you guys but I haven't found depth of bullet seat measurements anywhere. I loaded first twenty today and didn't adjust seater die, beyond the first install screw down to contact with cartridge at top stroke then back off one full turn and set. After the first round, I checked the OAL and it was exact to specs so I kept it that way. They all were good on OAL with two bullet types.

    This thread makes me wonder where are these seat depth numbers do I need to worry about it if OAL is fine, can I screw up not knowing this number?

    I'm using Hornady book and Speer book for now, maybe I missed it somehow

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    Quote Originally Posted by kodiakrain View Post
    This may sound crazy to you guys but I haven't found depth of bullet seat measurements anywhere. I loaded first twenty today and didn't adjust seater die, beyond the first install screw down to contact with cartridge at top stroke then back off one full turn and set. After the first round, I checked the OAL and it was exact to specs so I kept it that way. They all were good on OAL with two bullet types.
    Quote Originally Posted by kodiakrain View Post

    This thread makes me wonder where are these seat depth numbers do I need to worry about it if OAL is fine, can I screw up not knowing this number?

    I'm using Hornady book and Speer book for now, maybe I missed it somehow
    It is not always listed but it can be found at places like these if it's not or just google it up or ask here.

    http://en.wikipedia.org/wiki/.270_Wi...r_Short_Magnum

    http://data.hodgdon.com/main_menu.asp

    http://www.handloads.com/loaddata/default.asp?Caliber=270%20WSM&Weight=All&type=Rifl e&Order=Powder&Source=

    It's not as picky in a rifle as to safety like it can be in a pistol. You got to move the bullet a long way to change the volume of a bottle neck case a couple percent and that makes them more forgiving.

    In rifle OAL is one of the best things to play with to make your gun shoot better. When you get the other basics down and are ready to play with OAL post a thread about it and you will get tons of suggestions, tips, and tricks to try out.

    With your 270wsm the callout is 2.860” and you will be in the 2.700"-2.900" range once you start playing with it. The 2.900” is probably tight to the lands of your rifling if not past and it’s usually best to be about .30” off them, or .30” free bore. Gets confusing so stay at the 2.900” callout for now.
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    OAL is the number that you usually use for pistol. However, it is hard to find data for all the different bullets that are made. Normally OAL for a given weight bullet will work for any bullet of that weight. If it doesn't then adjusting the seating plug a quarter turn at a time and watching for pressure will usually keep you out of trouble.

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    Quote Originally Posted by ADfields View Post
    Gets confusing so stay at the 2.900” callout for now.
    OOPS . . . I meant 2.860" call out as per standard diminution drawings for 270wsm.


    rbuck351, good post thanks for the help.
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    EKC...I didn't see the pistol chambering that you're loading. I'm assuming it's a cartridge for an autoloader. When loading for autoloaders (45ACP & 10MM) I use the OAL, just like others have posted. However, one thing I also do...always...is I run them through a Lee Factory Crimping die. It helps hold the bullet in place during cycling/chambering so that you don't get bullet pushback into the case during feeding...which would reduce the OAL of the cartridge and potentially increase pressures.

    Doc

  11. #11

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    Quote Originally Posted by Doc View Post
    EKC...I didn't see the pistol chambering that you're loading. I'm assuming it's a cartridge for an autoloader. When loading for autoloaders (45ACP & 10MM) I use the OAL, just like others have posted. However, one thing I also do...always...is I run them through a Lee Factory Crimping die. It helps hold the bullet in place during cycling/chambering so that you don't get bullet pushback into the case during feeding...which would reduce the OAL of the cartridge and potentially increase pressures.

    Doc
    I have loaded thousands upon thousands of revolver cartridges. Everything from 38's to 454's and never knew this. I was considering loading for my 40S&W and someone mentioned this danger to me. I feel kind of embarrassed for my ignorance on the matter. I shot a lot of full case loads like blue dot in my 44 mags.

    Are you guys telling me that I'm lucky that I got away with it all these years?

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    Like you, I loaded revolver (44mag and 454 Casull) for years before handloading autoloading calibers. With those big revolver cartridges I always had a bullet cannelure for correct sizing and applying a serious crimp to prevent bullet creep in the last rounds of the cylinder. However, the autoloading calibers typically don't have a bullet cannelure, and they headspace on the case mouth. A Lee Factory Crimping Die doesn't require a bullet cannelure to do it's job...I really like them, and I use them for all pistol reloading.

    Doc

  13. #13

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    Quote Originally Posted by Doc View Post
    Like you, I loaded revolver (44mag and 454 Casull) for years before handloading autoloading calibers. With those big revolver cartridges I always had a bullet cannelure for correct sizing and applying a serious crimp to prevent bullet creep in the last rounds of the cylinder. However, the autoloading calibers typically don't have a bullet cannelure, and they headspace on the case mouth. A Lee Factory Crimping Die doesn't require a bullet cannelure to do it's job...I really like them, and I use them for all pistol reloading.

    Doc
    Yup Doc, Thats exactly how I've always loaded for my revolvers.

    I will follow your advise on the crimp die.

    I have a brand new caliper in the drawer that I've never used. Looks like I'll be dragging it out huh?

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    Quote Originally Posted by elmerkeithclone View Post
    I have loaded thousands upon thousands of revolver cartridges. Everything from 38's to 454's and never knew this. I was considering loading for my 40S&W and someone mentioned this danger to me. I feel kind of embarrassed for my ignorance on the matter. I shot a lot of full case loads like blue dot in my 44 mags.

    Are you guys telling me that I'm lucky that I got away with it all these years?
    Don't feel too bad, I did the same thing and I doubt any of us live long enough to learn it all. Long skinny cases like 38/357 and long fat 44/45 are not that bad and you were in little danger unless you were already pushing the pressure bounders pretty dang hard.

    Like Doc I learned of it when I started loading 45acp, they are short fat little cases. The first batch I did would not feed and was shoving the bullet back so when I looked for a fix a friend pointed out the danger.
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    The bigger the case the less a given amount of set back affects the pressure. Small cases like 9mm, 380, 25acp,45acp and such are more dramaticly affected by setback. The faster powders used in the smaller cases makes it worse also.

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    Quote Originally Posted by elmerkeithclone View Post
    Thanks guys! I guess your never to old to learn something new.

    I have always bought pistol ammo in the bulk and left the empties lay for the range hounds to scarf. I guess its just a matter of never dealing with it until now!
    You can come and shoot at my range anytime..
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



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    I'll come shoot at your range Murphy.......as long as I don't have to compete against you. We haven't pulled a trigger yet and I'm already waving a white flag! I weren't born yesterday ya know! Smile!

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