Criticality of Case length - Safety Question


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Lovesbeer99
March 28, 2007, 07:19 AM
I understand that I should not exceed max case length and max OAL, but what about min case length to prevent me from seating the bullet to deep? Is the case length that is listed as Trim to Length for the load in my book the minimunm length? For instance my speer book lists for 125gr 38spl max case lenght as 1.155, but trim to length 1.145. Does this mean that I'm safe anywhere in between? Can I have safely load a case that is 1.150, and 1.148, and 1.147? I notice in my Lyman book that using the same exact bullet and powder that the trim to length is 1.149 and the OAL is the same as above.
All of this is centered around safety and not accuracy. I'll worry about that after these 1st initial boxes.

The other perplexing thing is the powder measure. My speer book clearly states that the DNR for the load is 5.7 grains, while the lyman book lists it as 4.0. Speer states that lower pressures could be a very bad thing and that anything less than 5.7 is too low. What gives? (I read the posts about "will the real max load please stand up" but I'm taking that post with a grain of salt as the poster clearly stated that he didn't read any books. I've read 2, and have previous experiance loading shotshells)

To be specific, both looks list the same components as
38 spl, unique powder, 125 gr JHP

Thanks and shoot safe.

Lovesbeer99

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Walkalong
March 28, 2007, 08:39 AM
Trim it to the suggested minimum and, of course, you will be fine. You would have to trim WAY short before having to worry about getting the bullet seated to deeply and rum pressures up.

Your chamber on the .38 will determine how long your case can be before you get in trouble. If the case is too long it can get past the chamber into the narrower throat area of the cylinder and then there may not be enough room for the case to expand and release the bullet cleanly. That is where pressures will go up. You can easily determine how long that is. I trim my .38 brass to 1.145 just as my Speer manual #13 recommends. Trim once and you will probably not have to again for the life of the case with the .38, but check it every 4th fireing or so.:)

I start in the middle of existing credible load data on anything I am not sure of.

Doug b
March 28, 2007, 08:46 AM
You'll find that case length is not critical in straight wall pistol cases as they will tend to get shorter with use.As a rule the only time they need trimmed is for a uniform crimp.My Speer #12 manual shows the same trim lengths as yours but says max.Cart. length@1.550" and their 125gr. JHP over all length 1.435".
The do not reduce data is there because of the possibility of sticking a JACKETED bullet in the barrel with a reduced load.

scrat
March 28, 2007, 10:02 AM
agree the only thing you need to be worrying about is going over the max length. then trim them. any cases you see that are way too short just chuck them but i doubt that will ever happen. cases tend to stretch not get short.

The Bushmaster
March 28, 2007, 10:08 AM
"tend to get shorter with use". Yeah...Maybe...I have found that auto cases such as 9mm X 19 and .45 ACP cases tend to stay the same length or grow very slowly. I have .45 ACP cases that I have been loading for several years that started out at .890 that are now .894. .38 Special cases also grow very slowly, though I have not had to trim them to return them to minimum length. I do, however, trim them to insure uniform length. .357 magnum is a constant battle to keep them at proper length and I do trim them.

Basically it pays to measure all or samplings of a set of fired cases each time you have resized them to insure that one didn't sneak up on you...:D

EShell
March 28, 2007, 10:29 AM
. . . As a rule the only time they need trimmed is for a uniform crimp. . .
IMHO, this is where the case length would first become an issue.

The cases MUST be of the same length to provide a uniform crimp mechanism, and this is normally more critical with jacketed bullets than swaged or cast. Non-uniform crimps will lead to all kinds of problems, from bulged case mouths to vertical groups to a migrating bullet locking up the cylinder.

. . .agree the only thing you need to be worrying about is going over the max length . . .
Going beyond maximum length (for your particular chamber) is definitely a safety problem.

One variable to consider is the wide lattitude of chamber lengths out there. This means that exceeding SAAMI max length might be very critical in one gun, but of no consequence in the next, which might have the chamber cut a few thousandths longer. One exaggerated example of this excess length is where .38 Special might be fired in a firearm chambered for a .357 . . . there is really no way you'll ever be in 'danger' from a "long" .38 case.

Staying below "SAAMI maximum" is the simplest way to stay on the safe side, but your chamber can be guaged to see what you can really get away with. If you're shooting a .38 Special firearm, you can trim a .357 case down a little at a time until it will finally chamber fully. De-burr, but do not chamfer the case, you want it to be a square as possible. Do not force it into the chamber, use it like the soft measuring tool that it is. Measuring the resulting case length will be a reasonably accurate guage of your actual chamber length.

scrat
March 28, 2007, 10:32 AM
each time i read this i am thinking. so i will ask. did you trim them to short if so thats where you need to be careful. then depending on what type of case trimmer you are using make sure its adjusted and being used properly.

Doug b
March 28, 2007, 11:56 AM
"357 constant battle to keep at proper length" for sure I trim all casings requiring a good crimp after every fire.

Matt Dillon
March 28, 2007, 12:53 PM
Got .38 special and .357 Magnum cases, I trim each and every time, using the Lee trimmer system, very inexpensive and consistent. Then you are assured of having a uniform roll crimp.:)

Lovesbeer99
March 28, 2007, 06:43 PM
Thanks for all the responses. To be clear, my cases are not too short, I was just wondering what the lower limit of a safe load was as it's not listed anywhere. Only the Max length is listed in all the manuals as far as I can tell.

Also, I'm not sure my questions was answered. My concern is going larger than the stated Trim-to-Length. The Speer 13 says to trim to 1.145 and my cases are more like 1.149, 1.150, 1.147. I didn't trim them as they were not anywhere near the max length of 1.155. So is it ok to load these, and do I need to be conserned from a safety stanpoint of having 3 different size shells in the same batch?

Thanks.
Lovesbeer99

Walkalong
March 28, 2007, 06:48 PM
do I need to be conserned from a safety stanpoint of having 3 different size shells in the same batch?

No. You will get a better, more uniform crimp if you do, and this will help give you better, more accurate ammo.

Vern Humphrey
March 28, 2007, 07:10 PM
The newer Lee crimp dies automatically adjust for slight variations in case length, so I don't bother to trim the pistol cartridges I use with these dies. For other cartridges like the .45 ACP, I use a taper crimp and crimp by feel -- again, no need for trimming.

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