New Bullets, New Issue

[fxvr5]

First, ignore the OAL in the manuals.

Now, determine what OAL is required for this loaded bullet to fit in your barrel(s). Use a magic marker and follow the method in the link below to determine what OAL will fit in your barrel until the round will free fit and rotate in your chamber.

https://www.shootingtimes.com/editorial/reloading-tips-the-plunk-test/99389

Then tell us what that OAL is.

P.S. That bullet has a very short nose so it looks like it will require a short OAL. There's nothing wrong with this bullet. It's just a different shape than what you've loaded before.

P.P.S. You need to do this for EVERY new bullet you load with. Really.

 

[NMexJim]

I confused by your pictures. In the pic w/ the 3 bullets, the one on the right looks very over crimped, but that may just be the light. Looking down the side of the casing, I can't see a bulge, so maybe just light. The middle bullet looks almost roll crimped. Can you give us a mic reading right at the mouth of the two? That reading should be somewhere between .377 to .380, maybe .381 with a .356 bullet.

In the second picture, is the case being held up by the bullet tip, or is it the case jamming in the gauge? Maybe a case bulge? Didn't get the flare ironed out? If you lift the gauge, will the case seat deeper? Mic the opening where the bullet would pass and you'll probably get .355. A .356 bullet will at least enter the opening, but may stop where the ogive to the shank measurement opens to .356. Can you take a pic of the bullet end of the gauge with a round seated? If the bullet is not touching, then you've got a case problem most likely.

I think it's hard to tell at this point. Maybe too long, maybe case issue.

I see you're using mixed brass. Is the problem worse w/ one maker?

 

[9mmepiphany]

Overcrimped and slightly buckled the case...?

That's what I'm seeing in the first picture too. Either not starting the bullet straight of crimping too early

I was going to ask if you are seating and crimping in the same die as you are starting to shave some of the coating...that will cause your bullets not to pass the case gauge.

Coated bullets require that you add a bit more flare to the case mouth

 

[PO2Hammer]

If some plunk and some don't, doesn't seem like it would be an oal issue.
Maybe some are a little crooked ?

 

[nettlle]

Take a black marker and color the bullet with it. Seat the bullet short. Then progressively seat the bullets longer until the lands of the rifling just barely mark the black marking. Measure the OAL with mics or a caliper then set your seating depth .015" shorter. There is no other way. This is the best starting point. If they don't plunk at this length there may be something else wrong.

 

[NMexJim]

A .355 round nose will normally seat very deep into the barrel. SAAMI give a max length for all 9mm of 1.169 which is waaayyy out there. I normally seat 124 grain round nose at 1.140/1.130. OAL. The problem comes in where the chamber come down to .354 in the forcing cone. A lot of a round nose will get past that. But,.356 will be stopped a little shorter than a .355. So, OAL may well be a problem. Your 1.120 sounds good to me, but I don't have that bullet in hand.

9mm talks above about you're needing more flare to get a .356 started and seats correctly. Very true. The taper crimp should just be enough to take whatever that flare was out. I personally shoot for .379/.380. This will start a fuss but that all you should need. Much more and you bulge the case and crimp the mouth into the bullet.

So. Back off your crimp and seat your bullets a little deeper. Make a test round. Plunk it, gauge it. If the problems end with a lighter crimp, then you can creep bullet seat back out until you jam. Keep that measurement for that bullet. Back off of jam maybe .010/.015 and see how you like it.

 

[lordpaxman]

You need to do this for EVERY new bullet you load with. Really.

And I’ll add for every barrel that will see a round. Then write it down somewhere, along with all dimensions on the bullet.
I wouldn’t ignore the OAL in the manual, just keep it in mind that’s what the published data’s testing represents. If you need to go shorter you’ll be increasing pressure so make powder adjustments before you do.
If your sizing step produced brass which fits the case gauge, and the loaded round won’t, then be a bit more methodical then a lot of these posts which say “seat deeper” and try again. Figure out what the issue is first. Find your max and working COL.
Heavier bullets usually seat deeper in the case and produce a slight bulge especially if not seated straight. Larger diameter bullets will expand the overall D a bit more and even with a taper crimp may spring the brass back more.
If you can seat in one operation and crimp in another. Try to find what step in the process is the issue, don’t shotgun it. Good luck.