9 MM Crimp

Yes.

As you noted, .376" is a pretty fair average for factory ammo.

And you can't go wrong trying to duplicate it.

rc

Although there are variations in different heastamp case wall thickness, for semi-auto cases that head space on the case neck, I will use .020" more than the diameter of the bullet for determining the amount of taper crimp.

So, for .355" jacketed bullet, I use .375" taper crimp and for .356" lead bullet, .376" taper crimp.

* update - sorry had connection issues

Some factory barrels will tolerate slightly greater taper crimp but ultimately I will use the taper crimp that will allow the finished round to fall freely into the chamber with a "plonk".

Also, I am seeing more factory target ammo loaded with sometimes larger diameter plated bullets and larger .376" taper crimp.

on taper crimp, max diameter - 0.003" will serve you very well. It will serve you well for jacketed, lead, and plated bullets. If you look at a chamber drawing for 9mm, you will see that the taper after the shoulder, midway down the leade, is at 0.354", which is less than groove diameter. You are well away from headspacing with only the extractor and you would probably buckle cases with most taper crimp dies far before getting there.

I don't crimp 9mm.

Just be cautious with plated bullets to avoid damaging the plating.
If I loaded lead, I'd also be careful not to deform the bullets. When making some test loads, "pull" the bullets to check for excessive crimp.

I've had no problems with 9mm Berry's .356 diameter with the case-mouth at .3765-.377 tapercrimp. This feeds easily (drops in and out of the chamber) in two short-chambered CZ 75's.

Search works!

FI went looking and found this thread as I have just loaded my first batch of 9mm. Midway 124gr JHPs (must be somebody's seconds) over 3.9gr Bullseye seated to 1.094.

Anyway, I like crimping separately, esp. when working a new caliber or a new load. So I seated a couple of these then measured the case mouths: .376, .377. Perfect, and without a taper crimp. I had flared these only a tiny bit, and with the bullets seated they chamber easily in my CZ barrel and measure dead on spec. So, I'm not gonna crimp.

PO2Hammer, I'm with you on this one.

BTW, I used a set of Hornady titanium nitride dies, first i've tried of this brand. This was their first use, and all I did to them was disassemble, clean, and reassemble. I normally polish flare buttons and neck mandrels with Flitz, but this flare die doesn't appear to come apart. That said, guess its button didn't need polishing. I like these dies a lot.

9mm luger cartrige is straight walled. There is no crimp. Set your crimping die to remove any bell/flare you put on the brass prior to seating. Plan on jams or misfires if you deviate from .005" from straight. Too much crimp and the brass will enter freebore (misfire). Too little crimp and you'll have failure to feed. Same goes for 40s&w, 380auto, or anything that head spaces on the mouth of the brass.

edfardos

With my jacketed bullet practice ammo I don't even flare/expand the case mouths, I just resize/reprime, charge and seat the bullet. Occasionally a really dented case mouth will prevent a bullet from seating smoothly, but that's about 1 in 500.

With plated bullets I touch the case mouths with the Lee Universal Expander die. It's a conical flaring tool and it irons out any case mouth dings and I set it to flare maybe .002"-.003" to help seat the thin skinned plated bullets.

They don't need to be crimped after seating because the bullet has expanded the case enough to make the tiny flare disappear.

This has worked for me in many 9mm's including Glock, Sig, CZ, Marlin Carbine...
I use a Redding Competition seater die which help reduce 'skinning' the plated bullets.

Tests also show this to be the best way to prevent bullet set back, and accuracy sure doesn't suffer. Case life should be extended as well.

This method probably doesn't work well with progressive presses as you need to hold the bullet as it enters the seating die, but for turret and single stage loading I think it is the best way to make practice ammo.

For serious ammo I would use a separate taper crimp die and bump the case mouths just to be sure any dings have been ironed out.

edfardos, I'm fully aware of all this. That's why I test chambered and measured the case mouths. None deviate more than .002.

Did you read my post?

Thanks, PO2Hammer. I use a Hornady LNL single stage press and don't load high volumes. I actually like doing this slowly and carefully; I see no need to turn it into a factory job.

They don't need to be crimped after seating because the bullet has expanded the case enough to make the tiny flare disappear.

Click to expand...

That effect seems to be exactly what happened for this load. Had I not read your post, I'd be sitting at my bench now picking nits to get the taper crimp right, even though my calibers and my barrel were trying to tell me not to. There's a lesson!

I could easily reset the die to smooth the mouths, but they don't appear to need it. I'll shoot these and see how they go; if unsat I'll try smoothing them out next time.

9mm luger cartrige is straight walled. There is no crimp. Set your crimping die to remove any bell/flare you put on the brass prior to seating. Plan on jams or misfires if you deviate from .005" from straight. Too much crimp and the brass will enter freebore (misfire).

Click to expand...

Closing the bell is call a taper crimp.
9mm is straight but "angled/tapered" walls out to the base, not straight vertical wall like a 40cal/45acp.
With my 9mm Sig and two CZ's, the case and bullet would have to be literally "crushed" evenly to not seat on the case mouth. I won't say it's impossible to do, but it's SURE not an easy mistake to make.

Walkalong said:

The 9MM is a tapered case.

Click to expand...

Yes, 9mm is a tapered case, but the walls are straight.

Parallel walled and tapered walled would be better descriptions but I guess I could never change years improper nomenclature.