Sammi

[9-toes]

Been playing with the .380. I have two guns that slug out to just about 357. The wall thickness of the brass I'm using comes out to almost .020 total putting me at 377. With this small of a case the tolerances are pretty tight. I have some dummy rounds made up which seem to chamber just fine. I understand that there will be some elastic compression between the case and the bullet and that these readings are probably not absolute. My question is with the SAAMI recommendations stating that the case mouth should not exceed .373 - how much do I need to worry?? I understand that SAAMI is the standard that manufacturers must adhere to but as casters is there a limit one should try and keep to?

[runfiverun]

don't tell your gun about the specc's.
if you have a thou or two for the case to open and release the boolit you are fine.

[Gohon]

Maybe it is just me but I can't make heads nor tails of what you're asking. What slugs at .357? If it is the barrel then that .355 bullet is going to rattle all they way through it. Besides, the bore diameter has nothing to do with how a round will chamber. If the dies you're using are doing their job the case mouth will be at .373 when sized. My casts I make for my 380 are sized at .357 and when loaded they chamber and shoot just fine. I guess it is the reference to .357 that is throwing me............

[9-toes]

Gohon - the concern is with a set of 380 pistols where the barrels slug out at 357. With case wall thickness at .020 total and a cast bullet sized to 358 this exceeds the SAAMI recommendation of 373 for case mouth. I was looking to see if there was a point in these dimensions that a caster should not exceed. Run pointed out that having a few thousands in the chamber for bullet release would be a good idea and that is the kind of info I was looking for.

The other concern I guess I was trying to voice is that of stretching the case trying to seat such a large bullet and what forces that might apply on the bullet size. My overall goal here is to take some small pistols and try and get the most accuracy out of them.

[noylj]

SAAMI will tell you that their specs and data apply ONLY to the industry and NOT to reloaders. Reloading will often not meet SAAMI "specs.", as those are for industry testing and control.
You are ONLY making ammunition for YOUR specific gun. You may, within the range of normal reloading procedures, vary dimensions to those that work best in your gun(s).
I have a Browning Hi-Power with a barrel that meets manufacturer's specifications (Browning told me so when I complained), although the groove diameter is 0.3588". Upper limit for manufacturer, at least at that time, was 0.362".
It is clear that, in that barrel at least, I have to use 0.359+" cast bullets and 0.357" jacketed bullets are better than 0.355". Thus, I tailor the load to the gun.
In particular, do not consider SAAMI COL dimensions as having any applicability to your gun(s). Those dimensions are the maximum COL for industry testing and are NOT maximum for reloaders -- and I take them as being the minimum COL that any manual's reloading data pertains to.

[Gohon]

9-toes, I guess I kept looking at the .357 you said the barrel slugs at which is a non issue as far as the chambering of a round. The dimensions for a .380 chamber diameter are larger than the SAAMI spec for case diameter. If you want to know what you are really dealing with, just slug the chamber end of the barrel and drive the slug back out and measure. Slugging the entire barrel will not give you chamber dimensions of your gun.

Chamber and bore dimensions will vary from manufacture to manufacture. That's why it is often recommended for one to slug the bore and chamber to see what they have to work with when reloading. Ammo manufactures follow SAMMI specs so their ammo will chamber in all guns regardless of what the gun manufacture has cut the chamber at. My 380 reloads measure at .374 at the case mouth but they chamber just fine. About the only SAMMI spec I pay attention to is pressure and recommended COL's never seem to match my reloads.

Wall thickness of the case may or may not affect your reloads. Your sizing die will put the case at the proper dimension and with the soft lead normally associated with something like a 380, the brass will most likely swage down the bullet. However if there should there be a slight bulge, if it still chambers then you're still set to go. If that is of concern you can always purchase the Lee Factory Crimp Die which has the carbide ring that will swage the final reload to factory specs but I think you will find accuracy a lot better with a over sized cast lead bullet.

Hope this helps..............

[ku4hx]

What does "just about 357" actually mean? .356" or .358"?

All the numbers aside, what you want is for your overall length to be such that the boolit doesn't impinge on the rifling (and thereby get stuck) and your case neck diameter such that the case doesn't stick in the chamber. Using your barrel as a gauge, you want your rounds to drop into the chamber with a "ker-plunk" and fall freely out when the barrel is inverted. Once you have those conditions satisfied, make your measurements and record them for future reference. You may have to have slightly different cartridge dimensions for each gun.

And, or course, you need the loaded rounds to fit the magazine and chamber properly when the slide goes into battery.

[blackthorn]

You might want to spend some time reading the various threads on this (and possibly other) site(s). At least take the time to read the "stickies" on this forum. Most, if not all your questions will be anserd. From the way your posts are structured, it does not apear you have bothered to try this much. Have a great day.

[ku4hx]

you might want to spend some time reading the various threads on this (and possibly other) site(s). At least take the time to read the "stickies" on this forum. Most, if not all your questions will be anserd. From the way your posts are structured, it does not apear you have bothered to try this much. Have a great day.

+1 ... :coffeecom

[9-toes]

Blackthorn - ku4hx - not really helpful info - seems trollish in some parts. Runfiverun and noylj - thank you for your feedback it's appreciated.

[bobthenailer]

If the loaded rounds will chamber & extract in your gun reguardless if there .355 to .358 dia cast bullets are used, Dont worry about case buldge its only cosmetic
Ive been loading for the 380 for about 30 + years and currently have a old OMC back up & a Keltec , and have loaded for a few other brands, and i have allways used .357 dia cast bullets in all of them with no problems.