Although I have reloaded .380 and 9 mm, at this time I only reload .45 acp. One of the many measurements that seems to be critical to reloading is the overall cartridge length. My questions are; How accurate does this need to be? Should I use calipers to measure? Should I use one of those templates? Should I have both? Thanks in advance for the help reloaders.
Overall cartridge length
- Thread starter bigdogdaddy
- Start date
Dial calipers are a very good items to have. If you watch Harbor Freight Runs digital ones on sale for 9.95 sometimes.
RICHGCOOP
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RICHGCOOP
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Sounds good. I may look at Lowes tomorrow. I am sure they will be higher, but I have a gift card from there. 
For measuring overall length of cartridges that I load, I always use a caliper - either a dial type or, more likely, a digital type. The digital type has the advantage of preventing an error due to a mistaken reading of the vernier.
I try to keep the batch within .005" (five thousandths of an inch). Some bullet types have shapes that aren't quite uniform enough to keep that tolerance but I always do what I can to minimize the spread in the batch.bigdogdaddy said:
Thanks. That helps. I will definitely go digital on the calipers. I don't see some of those tiny lines quite as well as I used to.
D
Denny4kids
Guest
I think we could get into trouble if we just pick the OAL number from a hat. Depending on what bullet we use this length could differ by .080 of an inch and the powder charge can vary by 33%. This data is from one book. If we can find data for the exact bullet we plan to use I believe the load will be safe. I guess what I'm trying to say is if we seat a bullet too deep the pressures may end up in the +P range or beyond. Den
Exactly right Denny. I don't think anybody gave an overall length, because as you indicated the recipe (my word) will be different based on powder used, bullet, etc. I was more curious in regards to how exacting the measurement needed to be. Skip said he liked to stay within a tolerance of .005, which I think sounds reasonable. What about you? How much variation are you comfortable with?
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Denny4kids
Guest
I have heard that when the batteries get low in some digital calipers they can give false readings... :-\
Also on a Auto pistol cartridge ....if the OAL is to long and depeding on the bullet type when the slide closes...the bullet may hit the lands and groves and force the bullet deeper into the shell case causing very high and dangerous pressures.....And maybe a Kaboom....Denny4kids said:
I respect my guns. I respect my powder. I respect my primers. I fear the big kaboom. I am very careful reloading, which is why I asked the tolerance question. As a relatively new reloader two of the more surprising things I have learned is how important and precise the "dead air space" is between powder and bullet, and how lonely that little dab of powder looks in my .45 casings compared to what is in my 9mm casings. ;D
BDD, I almost always get the overall length data from the bullet manufacturer's suggested loads for their bullets. I don't generally buy bullets that don't have accompanying load data for them. For the bullets that I cast, I generally have info from the manufacturers of my bullet molds.
Thanks Skip. I have done the same. I am still using Hornady bullets from the first shipment of goodies me and my buddy bought a year ago so the load data I am using is still the same. My next batch will be my first complete solo flight reloading from start to finish. Up until now I have done about everything, but had him watching or at least acting like he was.
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Denny4kids
Guest
This month's Handloader Magazine has another great article about loading the 9mm Luger. The author states that seating a bullet .040 deeper could cause a pressure jump of 6000 PSI. If this is true and is the same for .380 ACP we could be playing with dynamite. I wonder how far a bullet is set-back when it hangs up on a feedramp and the operator smacks the back of the slide to chamber the round? I'm not really worried about it, just throwing some ideas out there. Den
I make dummy ammo using real cartridge cases and real bullets. The bullets are crimped into the cases exactly the way I crimp live ammo. I've run many of these dummy cartridges (in several calibers including 9mm and .380 ACP) through the appropriate firearms dozens of times with absolutely no noticeable bullet setback into the cases. By "no noticeable", I mean that the overall length measurements after cycling the dummy ammo fall within the range of overall lengths for the bullet type and cartridge.Denny4kids said:
On a really rare occasion, I've had a dummy round come out with a slightly shorter overall length, but those have been rather beat up with use already.
I would also "assume" that bullet set back would be much more critical/dangerous in some calibers than others. I know when I look into a 9mm casing there is not much empty space between the bullet and the powder, as opposed to the .45 that looks like you shorted the powder drop.
COL for loaded rounds is always important, but don't forget the case "trim" length before reloading. Most semi-autos seat on the case mouth and it must be within a reasonable tolerance.