9 mm case bulge

Stupid question

If there is no canelure, how do you know how deeply to,set the bullet. I had a gunsmith tell me to seat to the shoulder of the bullet yet I see several examples herein submitted where the bullet is seated well above the shoulder. Bottom line is, I loaded the 124 gr to the shoulder using a slight crimp and I saw no noticeable bulge near the base. I fired 100 rounds. There were 4 or 5 jams and the slide did not always return to lock after the last round was fired. Other than that they performed fine. I'd still like an answer to the setting depth question however.
 
While reviewing some of the answers I realized you never mentioned an OAL. Reading your last post I'm gathering that you do not have a set of calipers. Correct? If so you need to go back to the basics, calipers are basic tool, you don't guess by looking at the shoulder. Most all FMJ pistol bullets will not have a cannulure.
 
Minimum overall length listed in your reloading manual for the load you are using. Not to long that they won't fit in your magazine.
 
If the bulge goes all the way around the case, it isn't a problem and can help prevent bullet set-back.
If only on one side, it indicates the bullets are being seated crooked (poor seater stem fit, seater stem not aligned with die axis).
 
Understanding COL (Cartridge Overall Length)

Per Ramshot:
"SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as
1) magazine length (space),
2) freebore-lead dimensions of the barrel,
3) ogive or profile of the projectile and
4) position of cannelure or crimp groove.
• Always begin loading at the minimum ‘Start Load.’"

Your COL (OAL) is determined by your barrel (chamber and throat dimensions) and your gun (feed ramp) and your magazine (COL that fits magazine and when the magazine lips release the round for feeding) and the PARTICULAR bullet you are using. What worked in a pressure barrel or the lab's gun or in my gun has very little to do with what will work best in your gun.
Take the barrel out of the gun. Create two inert dummy rounds (no powder or primer) at max COL and remove enough case mouth flare for rounds to chamber (you can achieve this by using a sized case—expand-and-flare it, and remove the flare just until the case "plunks" in the barrel).
Drop the inert rounds in and decrease the COL until they chamber completely. This will be your "max" effective COL. I prefer to have the case head flush with the barrel hood. After this, place the inert rounds in the magazine and be sure they fit the magazine and feed and chamber.
You can also do this for any chambering problems you have. Remove the barrel and drop rounds in until you find one that won't chamber. Take that round and "paint" the bullet and case black with Magic Marker or other marker. Drop round in barrel (or gage) and rotate it back-and-forth.
Remove and inspect the round:
1) scratches on bullet--COL is too long
2) scratches on edge of the case mouth--insufficient crimp
3) scratches just below the case mouth--too much crimp, you're crushing the case
4) scratches on case at base of bullet--bullet seated crooked due to insufficient case expansion (not case mouth flare) or improper seating stem fit
5) scratches on case just above extractor groove--case bulge not removed during sizing. May need a bulge buster.
 
If there is no canelure, how do you know how deeply to,set the bullet. I had a gunsmith tell me to seat to the shoulder of the bullet yet I see several examples herein submitted where the bullet is seated well above the shoulder.
Click to expand...
Cartridge overall length is a balancing act.
The factors reposted by noylj all contribute to the end product.

In the example posted above in my photo (122 gr LFP seated to 1.090" COAL), the determining factors were:
-Suggested COAL in published data for similar bullets.
-Enough of the bullet in the case to give me good neck tension.
-Seated deep enough to not jam in the throat.
-Seated as long as possible while maintaining reliable feed and function.
-I don't crimp 9mm -- I just remove the flare. (So seating to a crimp groove, cannelure, or driving band [lead bullets with no cannelure/groove] is a non-issue.)

That load has run just fine through every 9mm that has ever gotten a helping. It's on the mild side, as far as power level, but the dimensions are just fine for standard chambers (and magazines and feed ramps).

One down side of that particular load is that there is exposed lubricant. That lube may pick up contaminants that could be abrasive to the chamber and barrel. Generally, I avoid such. But, in this case, I knew the ammo would be well-stored and primarily used for plinking under controlled conditions. So the risk and likely exposure level are minimal.
 
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