Another keyhole question

[MilkMyDuds]

I am loading 9mm for minor PF (130) with Bayou 147gr FP and N320. I have learned that different headstamps have different brass wall thickness, and this difference can cause the same crimp setting to potentially crimp too hard on thick walls leading to keyholes. As a result, I have started sorting brass by headsteamps.

However, even with the same headstamp brass, I am sill getting occasional keyholes, 2 out of 20 or so. I am loading on 650 with Mr. Bullet Feeder. Lee sizing die, RCBS seating die (I dialed the die all the way back and made sure it does not touch the brass at all) and Redding taper crimp die.

I know the common wisdom for keyholeing is too much crimp on coated/plated bullets. I paid extra attention to set up my taper crimp die to only remove bell at the mouth, without printing a crimp line. I confirmed this by pulling 10 loaded bullets from the headstamp I use, and measuring the base of the pulled bullets. No crimp line and all are 0.356'' at the base.

So what may be causing the occasional keyholes?

People have suggested that coat/lead shaving may also cause keyholes. On my setup I do get occasional coat/lead shavings, but very minor. When I tested the groups with shaving issues (I put aside the ones with visible coat shaved off after the seating station), none of them actually keyholed.

What did I miss?

[rancher5]

I am loading 9mm for minor PF (130) with Bayou 147gr FP and N320. I have learned that different headstamps have different brass wall thickness, and this difference can cause the same crimp setting to potentially crimp too hard on thick walls leading to keyholes. As a result, I have started sorting brass by headsteamps.

However, even with the same headstamp brass, I am sill getting occasional keyholes, 2 out of 20 or so. I am loading on 650 with Mr. Bullet Feeder. Lee sizing die, RCBS seating die (I dialed the die all the way back and made sure it does not touch the brass at all) and Redding taper crimp die.

I know the common wisdom for keyholeing is too much crimp on coated/plated bullets. I paid extra attention to set up my taper crimp die to only remove bell at the mouth, without printing a crimp line. I confirmed this by pulling 10 loaded bullets from the headstamp I use, and measuring the base of the pulled bullets. No crimp line and all are 0.356'' at the base.

So what may be causing the occasional keyholes?

People have suggested that coat/lead shaving may also cause keyholes. On my setup I do get occasional coat/lead shavings, but very minor. When I tested the groups with shaving issues (I put aside the ones with visible coat shaved off after the seating station), none of them actually keyholed.

What did I miss?

Different tho same concept, coated bullets i using Blue Bullets 147, actual 149gr rn use No crimp being they're thicker and hold absolutely, no keyholes ever,, using Lee Loaddmaster press,mixed stamp brass lots given to me by DL650 user as not useable, lighten ur crimp alot, IMOP

[Steve RA]

Slug your barrel, if the bullet fit to barrel isn't correct it will cause the problem you describe. Jacketed should be a minimum of .001 over groove diameter. Lead, coated and plated should be .002 to .003 over groove diameter. I personally prefer .003 but a lot of people say .002.

[thermobollocks]

What gun?

[MilkMyDuds]

MP9 Pro 5'' with BarSto barrel. About 5k down the barrel so far.

It also happens to my backup gun with 5'' KKM barrel (10k down the barrel).

Not likely to be the barrel.

[mpssrh]

What is your COAL (cartridge overall length)?

Barsto barrels often have chamber dimensions that can be smaller than what most of us are accustomed to. Their information says "mid-SAAMI specs," which is somewhat nebulous without actual measurements (not a criticism, just an observation). I have Barsto barrels and like them a lot, but I had to make allowances for their chamber size.

Do your cartridges pass the "plunk test"?

Best wishes.

[MilkMyDuds]

Yes, when i first received BarSto barrel it only takes 1.010'' OAL. I sent it back to ream the chamber a bit and now it is just like my KKM. Anything that passes the EGW gauge will pass the plunk tests on them.

Not sure if these have anything to do with the occasional keyholes.

[BeerBaron]

OAL can cause tumbling. try them a little shorter. low powder charges can also be a culprit.

[IDescribe]

MilkMyduds, run your PF up to 136 and see if it goes away. Seriously.

[IDescribe]

I have found my 147 loads start to destabilize somewhere between 15 and 25 yards if I load to a PF of 130-133. They don't actually keyhole, but groups open up more than they should. If I run the velocity up over 925, groups tighten up, and they're good to 25 yards. When I load 147, I load them to 935-940 feet/sec, so a PF of 137ish.

[MilkMyDuds]

I have found my 147 loads start to destabilize somewhere between 15 and 25 yards if I load to a PF of 130-133. They don't actually keyhole, but groups open up more than they should. If I run the velocity up over 925, groups tighten up, and they're good to 25 yards. When I load 147, I load them to 935-940 feet/sec, so a PF of 137ish.

MilkMyduds, run your PF up to 136 and see if it goes away. Seriously.

This might be it. I am currently doing 130ish PF at 880 fps. I will try 900 fps first see if it helps. Thanks!

[thermobollocks]

I don't remember when I gave 850 fps 147s a go in my M&P, but mine have been around 920 to 960 depending on what powder I use.

[GOF]

I have run Xtreme 147s at about 880 fps from a standard 4.25 M&P and a 5 inch CORE Performance Center (ported gun) without tumbling issues.

I am at a loss to explain this, other than your barrels may not like your bullet choice. Have you tried a different bullet? Maybe plated instead of coated lead? Some barrels just flat out don't like certain bullets.

[mjohn]

In my M&P 9L i am at 920 fps and no key holing. Zero's 147 FMJ & N320.

Edited September 25, 2015 by mjohn

[BitchinCamaro]

However, even with the same headstamp brass, I am sill getting occasional keyholes, 2 out of 20 or so.

10% is waaaaaay past what I would consider "occasional" . I would even say it's amazing.

I'm not a particularly good reloader but this year I'm reaching ~60k 9mm rolled and I can only remember five or six keyholes from when the bullet nicked a table or barrel or vision barrier (granted, I didn't look at every single hole I ever made). I stopped sorting my pistol brass (except for crimped WCC) about 30K rounds ago.

Try going the other way. Change (within the realm of safety) your parameters so you're intentionally getting 18 out of 20 keyholing. It may be a faster process of elimination.

Did you just back off your seating die off the case mouth, or did you back it way up into the cockles of the press? Maybe the seater face is unsupported enough that it's floppin' around when it's seating the bullet. I think you would feel the bullet seating off-axis though.

Try crimping the balls out of a few cases and see it it's actually pulling the jacket/plating/coating off to see if it's an issue. . Maybe borrow another crimp die altogether and see if that changes any probability of keyholes.

[thermobollocks]

It seems like if two different barrels have the same issue then it's more likely an ammunition issue.

[Sarge]

Not that you have to stay with them forever, but load 500 124's and see what happens. Some guns, barrels etc don't like 147's

[MisterB]

I had a problem with tumbling lead bullets on a gun that had never had an issue with lead/coated bullets. Tried different degrees of crimp, OAL, with no luck. I tried a slower burn rate powder and everything straightened out with light or moderate crimp. Might be worth a try.

[dauntedfuture]

You might want to check the twist on the barrels. I believe that some of the slower twist barrels are unreliable with 147g bullets. If the same loads work in that factory M&P barrel then thats a possible culprit. Too much crimp can upset things as well as a lee U die. I have been running all kinds of 147g bullets in a M&P 5" without issue.

[IDescribe]

There is a minimum rotational velocity a bullet must maintain to remain gyrostabilized. Rotational velocity is a function of twist rate and projectile velocity. 147 grain bullets at minor PF velocities in slower twist rate barrels might destabilize and tumble inside 25 yards where faster124gr bullets at the same PF won't. Over crimping and bad bullet to bore fit can exacerbate the issue. Run your 147 bullets up over 930 and see if that fixes it. If it doesn't, then you have eliminated rotational velocity as the culprit. Also, measure crimp right at the case mouth with the thin blades at the tips of your calipers. If you straddle the case mouth in the thicker part of the calipers, your actual measurement is probably two to three thousandths smaller than your calipers are telling you, and you are over crimping, which could also be the problem.

[MilkMyDuds]

Lead shaving issue was resolved. 0 lead shaving. I do believe it has some role in my previous keyhole issues. New problem emerged though. It was puzzling. BTW - I kept the MV at 880fps. I will be testing 930fps next.

1. The tumbling issue went away completely for about 2000 rounds or so when I used exclusively a specific brand of headstamp brass. 0 tumbling at any distance. This is with the BarSto barrel with twist rate of 1:16

2. The tumbling started again when I used the same ammo (loaded at the same time as the ones used in #1 above) to practice with my backup gun, KKM barrel, also 1:16 twist rate. Both my barrels are less than 1 year old. This time, the tumbling is really bad, nearly 80% of the rounds tumble. However, it only happens at <15 yards distance. Once I back off to 15 yards to 30 yards, 0 tumbling.

What would make bullets tumble at close range but not far? Why did it only happen to KKM but not BarSto with the same twist rate?

Edited October 28, 2015 by MilkMyDuds

[RPatton]

You say "On my setup I do get occasional coat/lead shavings, but very minor."

That said, you could expect to "have some minor keyhole issues".

I would try belling the case mouth more and eliminate the lead shaving issue.

Edited October 28, 2015 by RPatton

[MilkMyDuds]

You say "On my setup I do get occasional coat/lead shavings, but very minor."

That said, you could expect to "have some minor keyhole issues".

I would try belling the case mouth more and eliminate the lead shaving issue.

You are correct. My previous keyholes I do think lead shaving played a role in it, which was caused by a complex set of factors, including the Mr. Bullet Feeder expander die vs Dillon die, brass wall thickness, etc. I have identified and fixed that problem a while ago. I have had 0 lead shaving issue for the past few months.

The latest updates I just posted were using 0 lead shaving handloads.

Edited October 28, 2015 by MilkMyDuds