9mm keholing question


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cleanview
December 10, 2012, 08:35 AM
I have a new carry gun (bersa bp9cc) that I wanted to load some hotter loads to practice with. I bought some berry 124 RN and loaded 5.0 gr of unique (this I had crono at 1150 FPS out of a full size 9mm). out of the bersa 9mm it key holed, so I loaded a lighter 4.7 and it still keyholed. The full size 9mm had no problem with both these loads. Curiosity caused me to shoot several different loades out of the little 9mm and it shot everything else fine.

I am at a loss. Any ideas?

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helotaxi
December 10, 2012, 08:50 AM
Check the diameter of the bullets with a micrometer. Sounds like they might be a little small and the bore on your Bersa a little generous. The result is that they're not adequately engaging the rifling.

mgmorden
December 10, 2012, 08:51 AM
Check your crimp. Berry's are plated and and deform a little easier than jacketed bullets if you too aggressively crimp. You want to crimp just enough to remove the bell from the case and no more.

cleanview
December 10, 2012, 09:27 AM
I donít think that it has to do with diameter since other bullets shoot fine. And vice versa with the full size nine.

I had wondered if crimp could be the cause of my problem. I pulled one bullet to compare it to others and play with drop tests and the bullet was deformed from the crimp.

I have been reloading just over a year and have to admit that crimp is one of the things that still confuse me. I generally try to just take the flare out but for some reason I put a heavier crimp on these.

Sadly I have loaded all the berry bullets that I have. Supposed to get some more this evening and will give some more tests with a lighter crimp. I will just shoot thes out of other guns. Its funny how one thing will work out of one gun and then not in another.

helotaxi
December 10, 2012, 09:50 AM
Which leads me to believe that it is an issue with tolerance stacking. The bullets are just a bit undersize and the bore just a bit oversize. The bullets being slightly undersize isn't an issue by itself with a comparatively tight bore and the bore isn't an issue by itself with a comparatively large bullet, but put the two together...

What are you using to apply crimp?

mgmorden
December 10, 2012, 10:56 AM
I have been reloading just over a year and have to admit that crimp is one of the things that still confuse me. I generally try to just take the flare out but for some reason I put a heavier crimp on these.

The easiest way to setup the crimp die I learned from a Brian Enos reloading video.

Take a freshly resized case (that hasn't been flared) and raise it up in your press. Now take your seating/crimp die and start screwing it into the press. As soon as you feel it touch the case - stop. Tighten down your locking ring and leave it where it is.

Since you only went to the point of a resized case and no further, then you're taking exactly as much out of the case as needed to remove the flare.

918v
December 10, 2012, 12:04 PM
Seat and crimp separately. Or don't crimp at all. I don't. I barely flare the case mouth so the bullet will seat and just leave it there. Stopped crimping after seeing Federal ammunition uncrimped. Works fine since crimp does not do anything for bullet retention in auto loaders.

cleanview
December 10, 2012, 12:12 PM
I crimp with a lee die. my whole setup is lee.

I like the tip on setting up the crimp. I will try that.

Thanks

rcmodel
December 10, 2012, 12:24 PM
I generally try to just take the flare out but for some reason I put a heavier crimp on these.Typically, your normal jacketed bullets are .355".

Berry plated bullets are .356".

So, you need to back off your crimp die a little to get the same amount of crimp against the bullet you formerly got with jacketed bullets.

rc

bonez
December 12, 2012, 02:23 AM
The 9mm round headspaces off of the case mouth and thus SHOULD NOT be "crimped" into the bullet surface. As others have stated, the bell should just be "ironed out" of the case once the bullet has been seated. SAAMI spec for the mouth of the case is .380, with the web being .391.

Excessive crimp can cause the case to be pushed too far into the chamber, causing FTF due to light primer strikes, and a potential significant increase in pressure if it does go off (as the case mouth may be jammed past the "ledge" upon which the case headspaces. This could delay release of the bullet when fired causing the pressure to spike significantly). Not enough crimp can cause a failure of the cartridge to go fully into battery and jamming in the chamber, causing difficult extraction.

Do yourself a favor, set up your dies correctly and measure your resized/loaded brass to ensure that you are within spec. Doing otherwise leaves you open to a world of pain and regret. With the tools we have available today, "good enough for government work" doesn't cut it any more. Kinda reminds me of the good ol boy that turns to his bubba and says "Hold ma beer and watch this...". We all know what happens next.

johnandersonoutdoors
December 13, 2012, 12:07 PM
Guys,

Don't mean to hijack the thread but I am confused here. I recently started reloading and 9mm is my first caliber. I made up some dummy rounds and just ironed out the crimp making the mouth .380. I was getting setback and asked the community what to do. Someone replied back saying I should crimp to .377.

Now you guys are saying it must stay at .380 or else it could mess up the headspace.

I am now thoroughly confused.

EMC45
December 13, 2012, 01:38 PM
I am willing to bet your bullets are undersized. I have a 9MM (BHP) and it likes .358 sized bullets. Anything else is inaccurate.

HJ857
December 13, 2012, 01:42 PM
Every Berry 124 grain plated bullet I've measured averages .354 with a very few coming out at .358

918v
December 13, 2012, 03:21 PM
Someone replied back saying I should crimp to .377.

Someone does not know what they are talking about.

First, it is case tension that holds the bullet in place, not crimp. You should not be seeing any setback beyond .002-.003" per cycle. In some guns, like Glocks, you should not see any setback period.

I don't crimp my rounds. I don't get setback.

You need to review your reloading procedure: Are you sizing the case correctly? Are you belling the case mouth correctly? Is your bullet the right diameter? Are your dies in spec? Are your measuring instruments working correctly?

Most of the time bullet setback is caused by one or a combination of the following: too much bell, case lube inside the case, too much crimp (yes, that's right), bullet too small in relation to the expander.

1SOW
December 13, 2012, 03:33 PM
Not to add more confusion, BUT longer cases will crimp MORE than shorter cases. The farther the case goes into the die the more it crimps. Range pick-up cases vary a lot in length. Set the crimp for a "long case" (.750-ish) to maybe .378, the shorter cases will measure less crimp and be ok.

Hope this makes sense.

I have shot a LOT of Berry's plated bullets. They measure from .355 to .356 and the "TP" bullets just a skosh more mostly.

johnandersonoutdoors
December 13, 2012, 03:56 PM
918v,

I was experiencing setback to the tune of about .002 or .003 per cycle just like you said. I wasn't worried at first but then I cycled a few times and saw a total setback of say .006 to .008. I was worried because there may be times when a round gets cycled a few times (say if there is a malfunction or something).

I am using dillon dies and and powder die (expander). Resizing the cases by putting resizing die all the way down until it touches the shellholder. The one thing that was curious about that is when I run the cases up into the resizing die then the die no longer touches the shellholder, you can see a small gap. Then I belled a very small amount with the powder die, to about 3.81 or .382. Seated the dummy round to 1.135 and then simply removed the bell bringing case mouth back to .380 which is what I originally thought I should do (before getting advice to crimp to .377) and tested for setback using the thumb test against the workbench and did not experience any setback. It only occurred when I cycled dummy rounds through my M&P 9.

The brass is true once fired from my gun and the brass is in good shape. I was surprised to get setback because I figured there would be plenty of neck tension like I had read about previously. Thank you for the reply.

918v
December 13, 2012, 05:19 PM
On some guns the bullet nose impacts the feedramp harder than others. If all you're seeing is .002" per cycle then don't worry about it. If you need more security then consider wet tumbling in stainless media. This cleans the carbon off the inside of the case and creates more friction between the case wall and the bullet.

jwrowland77
December 13, 2012, 06:04 PM
That's what's I've always been told by multiple people, is after you get done doing your crimp on a 9mm round is you want the mouth and about a 1/8 inch below the mouth to measure .376-.378

1SOW
December 13, 2012, 06:27 PM
after you get done doing your crimp on a 9mm round is you want the mouth and about a 1/8 inch below the mouth to measure .376-.378

Actually, "just" below the mouth is best. The crimp is "tapered" from first die contact to to max contact. Within 1/16" will be where plating damage shows up most.

The measurement amount is approximate. Case brass thicknesses vary quite a lot.
The actual best measurement amount is 2 X the brass thickness at the mouth + the bullet diameter + a hair.
This gives full contact.

greyling22
December 13, 2012, 06:42 PM
I wouldn't obsess too much about crimp and headspace. While technically the 9 headspaces off the case rim, it can always headspace off the extractor if there is too much crimp and. Eyeball it, set it like mrmorgan said or however you want and then be done. Move on to a more likely issue: bullet size and/or powder charge.

I'd take a stab at dropping your load down to 4grn of unique and see if you are still keyholing. I've never used a plated bullet, but I shoot a lot of lead. generally when I get keyholing it is because I have too much oomph behind the bullet. too much or too fast of a powder.

however, feel free to take all my suggestions with a lot of salt. I've tried everything I know of, and the suggestions of both the thr and castboolits and still can't get a 9mm bullet to not lead heavily in my 9mm. Hot loads leaded and keyholed. I stay below 1050 these days.

might it also be possible the rifling is shallower on the bersa than on the other 9?

1SOW
December 13, 2012, 06:55 PM
I wouldn't obsess too much about crimp and headspace. While technically the 9 headspaces off the case rim, it can always headspace off the extractor if there is too much crimp and.

NOT a safe practice. It can also headspace off of the leade or rifling and cause skyrocket pressure increases. While you and your specific pistol may not experience ppotential hazards doing this, OTHER pistols and bullet shapes CAN. It mis-leads inexperienced readers into believing this paractice is OK to do. IT is NOT a safe practice.

bonez
December 13, 2012, 07:10 PM
^ what he said! ^^^^^

greyling22
December 13, 2012, 09:34 PM
the intent was not to promote an unsafe practice, but to get the thread back to a more helpful track to the OP. It seemed like it was about to get bogged down in the minutiae of crimping and I felt it needed to get nudged back to the original topic of primary causes of keyholing. Iron out the flare, check, don't cut through the plating with too much crimp, check. A deep discussion on proper crimp is fine and dandy, but not really what the thread was started to discuss. But I'm not a moderator, probably not my place to do so. Ya'll carry on. :)

1SOW
December 14, 2012, 01:10 AM
The OP:
I had wondered if crimp could be the cause of my problem. I pulled one bullet to compare it to others and play with drop tests and the bullet was deformed from the crimp.

I have been reloading just over a year and have to admit that crimp is one of the things that still confuse me. I generally try to just take the flare out but for some reason I put a heavier crimp on these.

918v
December 14, 2012, 02:06 AM
When plated bullets keyhole, crimp is the first suspect. So, don't crimp. See if it still keyholes.

1SOW
December 14, 2012, 02:13 AM
918v, best suggestion so far, if the bullet doesn't have a sharp-edge base. Most of Berry's plated don't.

cleanview
December 24, 2012, 08:08 PM
Well. Sorry for the delay in responding.

I backed off of the crimp and that solved the problem.

Thank you for all of the replies.

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