MBC Plunk Test Failure

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Larson-Catz

Larson-Catz

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Ok guys, new member here and new to reloading... really new.
I got me a press, some brass, some dies, bullets and all the fun stuff. Read a couple of books and searched all over the net for the last few months. BTW, just cause it's on the Internet does not mean its true...
Here is my setup
Lee Classic Turret Press w/ auto drum powder measure (auto index removed for now)
9mm 124gr round nose from Berry's (250)
9mm 124gr "small ball" with Hi-tek from MBC
Hodgdon TiteGroup

Reading a couple of different manuals I was able to run off 10 of the Berry's bullets for testing with little problem using 1.15 OAL 3.6gr of powder which is the starting grains. Shell diameter at the case opening after crimp is .375. Plunk test worked good and I even made some dummy rounds to run through the mag and chamber to check for sticking.
I do see a slight "bell" at the top quarter of the round so I need to figure out whats causing that???

My Question is with the MBC bullets and the TiteGroup powder. Starting Grain is 3.6 with a OAL of 1.15. When I do this the plunk test fails and sticks in the barrel. From what I can tell I can chamber and feed rounds fine from the magazine but I'm not too keen on failing the plunk test. I'm guessing this is due to the shape of the MBC vs the Berry's

To figure out what it could be I painted a round with sharpie and stuck it in the barrel, what I found was the bullet needed to be set deeper as it was hitting the rifling. I adjusted my press and from what I can tell the OAL that works best for this bullet is 1.10.

Because I need to set this bullet deeper this will have a different pressure on the round when fired. If I'm using the starting charge but not the recommended OAL how can I determine a "safe" load to test with?

TIA
 
Larson-Catz said:
Ok guys, new member here and new to reloading... really new.
I got me a press, some brass, some dies, bullets and all the fun stuff. Read a couple of books and searched all over the net for the last few months. BTW, just cause it's on the Internet does not mean its true...
Here is my setup
Lee Classic Turret Press w/ auto drum powder measure (auto index removed for now)
9mm 124gr round nose from Berry's (250)
9mm 124gr "small ball" with Hi-tek from MBC
Hodgdon TiteGroup

Reading a couple of different manuals I was able to run off 10 of the Berry's bullets for testing with little problem using 1.15 OAL 3.6gr of powder which is the starting grains. Shell diameter at the case opening after crimp is .375. Plunk test worked good and I even made some dummy rounds to run through the mag and chamber to check for sticking.
I do see a slight "bell" at the top quarter of the round so I need to figure out whats causing that???

My Question is with the MBC bullets and the TiteGroup powder. Starting Grain is 3.6 with a OAL of 1.15. When I do this the plunk test fails and sticks in the barrel. From what I can tell I can chamber and feed rounds fine from the magazine but I'm not too keen on failing the plunk test. I'm guessing this is due to the shape of the MBC vs the Berry's

To figure out what it could be I painted a round with sharpie and stuck it in the barrel, what I found was the bullet needed to be set deeper as it was hitting the rifling. I adjusted my press and from what I can tell the OAL that works best for this bullet is 1.10.

Because I need to set this bullet deeper this will have a different pressure on the round when fired. If I'm using the starting charge but not the recommended OAL how can I determine a "safe" load to test with?

TIA
Click to expand...
I think you will be ok as long as you stick with the starting charge of TiteGroup until you have done more testing with this load. I've been loading 45ACP and decided to try X- Treme Bullets. They are plated 200gr. bullets. Because they are plated and not jacketed bullets I use lead bullet load data. When I loaded them to recommended depth 1.200 OAL. Mine also failed the plunk test. So I kept seating them deeper and deeper until they past the plunk test. Ended up at 1.180 OAL on starting powder charge. I've used this OAL with three different powders Bullseye, Unique and WST. No pressure problems at all.This has turned out to be the easiest load on my gun and most accurate. Sounds like you are doing everything the right way. Sounds like you have found a combination to experiment with. Have fun.
 
Also if you look at the bullets you bought from MBC on their web site you will see they recommend that you seat that bullet to approximately 1.08 OAL. You are good to go.
 
I'm new - really new like you - so take what I'm saying with a grain of salt. But if you're measuring your crimp correctly, I think it's possible you're crimping way too much.

I'm running the same thing as you with the exception of bullets... Titegroup powder with 124g FMJs. With .355" diameter bullets & an average case wall thickness of approximately .0120", that leaves me looking at ~.378" for finished crimp (.355 + (.0120 * 2)). My measured crimps run between .377-.379, which is right where I want to be based on those numbers, and my rounds have chambered perfectly and shot accurately.

As the 9mm headspaces off the case mouth, it sounds like you could be crimping to the point where it's allowing the round to fall too deeply into the chamber.

Hopefully someone who knows more will chime in (& I'm sure they will).

Even if this isn't the case, I'm thinking .375" crimp would be enough to undermine accuracy, particularly with lead/plated bullets. Have you pulled bullets afterwards & looked at them?
 
When I work up new loads, I usually load a bullet into an empty resized case with no primer to determine my OAL. I seat the bullet a couple of thousandths deeper until it passes the plunk test. Then, starting at the bottom of the load data, I work up. As long as you check for pressure signs along the way and work up slowly, you will never have an issue.

It sounds like you are already on the right track:)
 
azrocks said:
I'm new - really new like you - so take what I'm saying with a grain of salt. But if you're measuring your crimp correctly, I think it's possible you're crimping way too much.

I'm running the same thing as you with the exception of bullets... Titegroup powder with 124g FMJs. With .355" diameter bullets & an average case wall thickness of approximately .0120", that leaves me looking at ~.378" for finished crimp (.355 + (.0120 * 2)). My measured crimps run between .377-.379, which is right where I want to be based on those numbers, and my rounds have chambered perfectly and shot accurately.

As the 9mm headspaces off the case mouth, it sounds like you could be crimping to the point where it's allowing the round to fall too deeply into the chamber.

Hopefully someone who knows more will chime in (& I'm sure they will).

Even if this isn't the case, I'm thinking .375" crimp would be enough to undermine accuracy, particularly with lead/plated bullets. Have you pulled bullets afterwards & looked at them?
Click to expand...
SAMMI recommends .3800 but we are talking thousands of inch. I think you are both ok. Buy the way. What guns are you using new or used?
 
If you are at the starting load of Titegroup and the starting load is 3.6g, seating the bullet 5 mils deeper won't put you anywhere near max SAAMI pressure. The recommendation is to shoot 'em and see how they work. Chances are they will work fine. As for the "slight bell" of the finished round, you are not closing the flare enough with the taper crimp portion of the seating die.

  1. Seat a bullet to your desired 1.10" COL
  2. Lower the ram and unscrew the seating stem a couple of turns
  3. Loosen the lock ring and incrementally lower the die about 1/12th turn at a time until you see that the taper crimp portion of the die body is closing the bell. You can index the die with a magic marker on the die body and the lock nut and it cleans off easily if you don't want it there permanently
  4. When the case mouth is "vertical" (not really vertical because the 9mm case is tapered) lock the die body with the lock nut. You can go a few degrees beyond vertical, just make sure you don't turn that taper crimp into a roll crimp. The cartridge will headspace with the extractor most of the time, but with a loose extractor, the crimp could bury itself into the throat and cause a big spike in pressure which is not healthy for the gun or your body parts.
  5. Raise the cartridge back into the die and screw down the seating stem until it makes contact with the bullet
  6. Make a few rounds, check dimensions and plunk test them
  7. Go shoot 'em and adjust the load remembering that you need to stay 0.1g - 0.2g below recommended max because of the deeper seating and to allow for variations in powder drops
 
The 9mm is almost a special case unto itself due to the tapered chamber. Lots of cartridge irregularities will make a 9mm go partially into the chamber and then stop. Most common causes are: OAL, taper crimp diameter, buckled cases, and range brass from Major PF. More investigation is required on your part.

I see you did not mention the pistol you are loading for, but I will add this.... Not every bullet offered for sale can be successfully reloaded for every pistol sold. This statement is true of combinations including the MBC 124gr Small Ball and pistols for Eastern Europe, such as the CZ series and the Springfield XD series.

Hope this helps.
 
Jack B. said:
Also if you look at the bullets you bought from MBC on their web site you will see they recommend that you seat that bullet to approximately 1.08 OAL. You are good to go.
Click to expand...
Jack,
Can you send me the link on the MBC website please? I was looking for this last night and must have missed it.
For the guns I am using they are fairly newer. Glock 43 and a Sig P320 compact. I only did the Plunk test on the Sig and will deal with the Glock at a later time.
 
azrocks said:
I'm new - really new like you - so take what I'm saying with a grain of salt. But if you're measuring your crimp correctly, I think it's possible you're crimping way too much.

I'm running the same thing as you with the exception of bullets... Titegroup powder with 124g FMJs. With .355" diameter bullets & an average case wall thickness of approximately .0120", that leaves me looking at ~.378" for finished crimp (.355 + (.0120 * 2)). My measured crimps run between .377-.379, which is right where I want to be based on those numbers, and my rounds have chambered perfectly and shot accurately.

As the 9mm headspaces off the case mouth, it sounds like you could be crimping to the point where it's allowing the round to fall too deeply into the chamber.

Hopefully someone who knows more will chime in (& I'm sure they will).

Even if this isn't the case, I'm thinking .375" crimp would be enough to undermine accuracy, particularly with lead/plated bullets. Have you pulled bullets afterwards & looked at them?
Click to expand...

Yep i have pulled the bullets after and nothing looks out of shape or crimped to tight.
 
rfwobbly said:
The 9mm is almost a special case unto itself due to the tapered chamber. Lots of cartridge irregularities will make a 9mm go partially into the chamber and then stop. Most common causes are: OAL, taper crimp diameter, buckled cases, and range brass from Major PF. More investigation is required on your part.

I see you did not mention the pistol you are loading for, but I will add this.... Not every bullet offered for sale can be successfully reloaded for every pistol sold. This statement is true of combinations including the MBC 124gr Small Ball and pistols for Eastern Europe, such as the CZ series and the Springfield XD series.

Hope this helps.
Click to expand...
Thanks for this and its good info to have as i did not know that. i reloading for a Glock 43 and a Sig P320. More for the Sig than anything else as the glock is my wife's and she does not shoot near as often as i do
 
Schwing said:
When I work up new loads, I usually load a bullet into an empty resized case with no primer to determine my OAL. I seat the bullet a couple of thousandths deeper until it passes the plunk test. Then, starting at the bottom of the load data, I work up. As long as you check for pressure signs along the way and work up slowly, you will never have an issue.

It sounds like you are already on the right track:)
Click to expand...

Here are all my "test" OAL rounds. No caps... no Powder. The one on the far right is the one that works the best
 

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Those are blunt for a 9MM round nose, no wonder they have to be seated deeply.

.375 is a bit tight.

It's normal to have a slight "bulge" in the case where the bottom of the bullet is.
 
Walkalong said:
Those are blunt for a 9MM round nose, no wonder they have to be seated deeply.

.375 is a bit tight.

It's normal to have a slight "bulge" in the case where the bottom of the bullet is.
Click to expand...
ok..... thats good cause i have a few like that. i will try .376 and .377 to see if that works better.
 
OP, welcome to THR and the reloading hobby.
I've shot a couple thousand of the MBC SmallBall and yes, you have to load them "short". IIRC I loaded them right at the 1.08" As Walkalong said above, those are blunt.
Bullet profile has a big impact on the seating depth as the shape (ogive) determines where they contact the leade and/or start of the rifling. In my loading of some of the cast bullets I learned that I had to seat many of them deeper than the FMJ or Plated counterparts.
 
I loaded some of the MBC 124's recently with the same recipe I've used with Bayou coated. Like I always do when changing a component, I loaded a few and fired them to make sure they cycled. They worked fine so I loaded up 500 on my progressive. About a week ago I discovered they only work in the gun I tested them in, a Steyr S9. Just a bit too long for my other 9's, another lesson learned.
 
drunkenpoacher said:
I loaded some of the MBC 124's recently with the same recipe I've used with Bayou coated. Like I always do when changing a component, I loaded a few and fired them to make sure they cycled. They worked fine so I loaded up 500 on my progressive. About a week ago I discovered they only work in the gun I tested them in, a Steyr S9. Just a bit too long for my other 9's, another lesson learned.
Click to expand...

Funny, I tested in my Sig at 1.10 and worked just fine. Pulled the Glock out of the safe and it did not pass. Now it's time to set at 1.08 and test again... fun times!
 
With Cast bullets you may see a slight bulge at the case mouth, nothing to worry about as long as the round chambers.
As a side note when I was using MBC bullets my 9mm pistols all seemed to prefer the cones.
Don't forget the 5% discount MBC offers THR members with the code.
Sprinklers are on at the moment but I will see if I have one with the acceptable bulge and take a picture of it for you.

If you are at start charges I wouldn't worry to much about a little deeper say 1.08 vs 1.10.
 
I use the MBC 124g coated with either Win or Blazer brass. I have a half dozen 9mm's, all Ruger and Sig. I set my OAL to the recommended 1.08 and they all plunk test, chamber gauge test, and cycle fine in all of my 9mm's.

I suspect a crimp issue
 
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