Dillon SDB 9mm Resizing Issue

Chilidip

Chilidip

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I'm having an issue I'd like to resolve and I'm out of ideas at this point. I see folks talking about averaging 3 or 4% of their rounds that fail case gauge but currently I'm running around 30% that fail. For our Provincials last weekend I loaded 500 rounds and only 352 passed case gauge and were tested in both a Shockbottle 100 round gauge and then several were double checked in a DAA gauge. The rounds that fail do so by just the smallest amount right at the bottom almost like they aren't being resized all the way down.

I talked with Dillon and we ran through the usual checks and they sent me out a new resizing die and I also changed out the blue friction plate even though I passed that test that indicates if it needs replacement. 99% of this brass is my own once or twice fired brass from factory ammo I bought. All of the ammo that fail gets used on practice nights and all feeds and runs reliably so I'm guessing my barrel is a bit looser but I'd like to get this resolved, any ideas?
 
There are two simple checks you can do. I have had to quarantine batches of ammo until I ran through the process below and checked again and they were fine.

1: is your case gauge clean? They have a tendency to build up small amounts of debris / lube in them and give false readings. A quick shot of brake cleaner and an air compressor will clean it out.

2: is your brass clean? If you use lube on your 9mm while loading flakes of powder and other debris can cause incorrect readings. With your batch, the ones that failed you can give them a second try and if you drop them into another hole it might pass.

As mentioned above I had the appearance of the brass off of my Camdex processor failing case gauge occasionally until I learned that I need to actually clean the gauge on a regular basis.
 
Good thoughts, the 100 round shockbottle gauge was brand new first use and the DAA has only checked maybe 2,000 rounds to date. I don't use any lube during the process and after wet tumbling the brass is as clean as I can get it.
 
All of the ammo that fail gets used on practice nights and all feeds and runs reliably
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I believe THIS is the operative issue. The only important factor is does the ammo feed and fire? If yes then everything else is entirely irrelevant.

Somehow we managed to load billions upon billions of rounds collectively prior to the introduction of "case gauges". Sometimes ignorance is bliss and as long as the thing works, who cares?
 
Got off the phone with Dillon, I do have the correct shellplate installed. We ran through a few things including measuring some of the failed rounds with a caliper. The opinion of the guy at Dillon is that because I'm loading 147's that certain brass has different thickness and isn't compatible with 147's. He asked me to look through my failed rounds and he figured I'd see a lot of the same brass. This theory didn't really pan out as there was a decent mix of all headstamps and the only brand with a greater representation was Blazer but that's easily explainable by the fact that it makes up about 40% of my brass collection.

He wants me to do up a batch of 124's and he figures I'll see this issue disappear, colour me skeptical at this point.
 
Suputin said:
I believe THIS is the operative issue. The only important factor is does the ammo feed and fire? If yes then everything else is entirely irrelevant.

Somehow we managed to load billions upon billions of rounds collectively prior to the introduction of "case gauges". Sometimes ignorance is bliss and as long as the thing works, who cares?
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I care to the point that I don't want a failure at a major match due to an ammo issue. I don't have an issue using it up on practice nights but it would be nice to resolve the issue if I can so that I don't have to load 40% more ammo each time I'm loading for a match especially if I happen to be pressed for time.
 
Chilidip said:
I care to the point that I don't want a failure at a major match due to an ammo issue. I don't have an issue using it up on practice nights but it would be nice to resolve the issue if I can so that I don't have to load 40% more ammo each time I'm loading for a match especially if I happen to be pressed for time.
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Does the "bad" ammo feed and fire fine? Then there is nothing wrong with it in your gun. Forget the stupid gauge and just load ammo that works in your gun.



Got off the phone with Dillon, I do have the correct shellplate installed. We ran through a few things including measuring some of the failed rounds with a caliper. The opinion of the guy at Dillon is that because I'm loading 147's that certain brass has different thickness and isn't compatible with 147's. He asked me to look through my failed rounds and he figured I'd see a lot of the same brass. This theory didn't really pan out as there was a decent mix of all headstamps and the only brand with a greater representation was Blazer but that's easily explainable by the fact that it makes up about 40% of my brass collection.
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The Dillon guy is an idiot. ALL 9mm ammo should be sized for the caliber. The weight of the bullet is entirely irrelevant to its diameter.
 
I've seen some bullets that bulge the brass. But I've seen some ammo that has a bulge around the base.

The first thing I'd do is mark the sides of a couple of the sticky rounds with a stripe from a felt pen. Then seat the bullet in your gauge and LIGHTLY press it home than pull it out a few times. The idea is to scuff away the felt marker at the point of contact. The wear mark in the ink will tell you if your bulge is at the base or if it is related to the bullets.

If it is the bullets then where on the side is the mark? If it's near the mouth you might just need a touch more taper crimp. If it's lower then you might need to live with the issue. 147's stick down into the cases a bit further than the lighter bullets. And side walls of cases are tapered in thickness so a deeper seating often means a slight bulge. If the bullets "plunk test" in your barrel just fine then you can take note of how close they are in the gauge and consider others that seat the same to be OK even if they stick a little.

Take a touch more time to seat the bullets straight up when placing them into the case mouths as well. If the bullets are pushed in cockeyed they tend to push out the side walls at first until the nose gets forced straight. Run a test on 10 of each started at slight angles to those started at what looks straight to your eye. If the ones that start out looking more straight turn out to test better then take a touch more time to start out straighter. A touch more flare in the powder die can be a good aid for setting the bullets in place straighter more easily. A "touch" being about an 1/8 turn on the die to just widen the mouth up by an amount you'd never see but which makes it so the bullet can start out sitting down in the case a touch more deeply and stable until seated. Along these lines I aim for the bullet base to seat down easily into the mouth and begin to tighten when a round edged plated or jacketed bullet is about 1.5 to 2mm deep. A sharp edged base bullet as seen on many cast bullets I aim for a 1 to 1.5 mm friction point depth when placing them.

On the other hand if the bulge is down near the base you may not have any other option than the "bulge buster" mentioned already if you're worried about this and the gun barrel won't cleanly plunk test the suspect ammo.

Keep in mind that if you can plunk test the suspect ammo in your actual barrel you can also rest a finger on the exposed head and see if there's any "rattle room". If the suspect oversize ammo has a touch of rattle then you are worried about nothing. I'd even go so far as to suggest that your check gauge in this case is a waste of time. At least as it tests for THIS gun.

If it were me in such a case I'd dedicate one of the gauges to that particular gun by easing out the chamber. It should still reject ammo which will be even close to snug in the gun's actual chamber. But as it seems from your description it's being WAY too pessimistic. If you make it so the previously suspect ammo JUST BARELY drops in and out cleanly and if that same ammo has a touch of rattle room in the barrel then you're still doing a valid check.

You might even want to make up a "no go" gauge for a comparison test round for your drop test gauge. Particularly if you would consider opening up one of the gauges to a custom size to use on your one pistol. You would do this by testing spent but clean brass until you find one which is round, not oval, but which won't plunk cleanly in the barrel chamber. Now PARTIALLY size it using a short stroke and test frequently until it just barely plunks in the chamber with perhaps the lightest of finger pressure and where you can't feel any rattle. If it won't drop of its own weight but extracts easily with a light fingernail pick that's just right. If you go too far try again with another case. When you get it just right seat a bullet in it and crimp. Retest in the chamber. If needed remove the decapping pin from your sizing die and partially resize this "go" round until it just barely plunks and drops clean thanks to the weight of the bullet. It should not have any perceptible rattle for this "go" tester. Now for use in your modified test gauge this will be your "NO GO" test round. You want your test gauge to reject such a round. In use such ammo may or may not run cleanly. But it's too much of a risk to take. I'd file two small nicks in this round to mark it as such.

Now repeat all this but this time size it down a trifle so it has SOME rattle room Not a lot mind you. If your previously suspect ammo functioned well in practice sessions you might aim for your smaller round to roughly mimic the amount of rattle those rounds have. But don't make it smaller. Aim for the round to jam in the gauge the same way your "bulged" ammo sticks. Since you know this size runs in your gun just fine you can mark this one with one file notch as your "GO" test round for your gauge for THAT gun. Now you can work towards polishing out the gauge to just fit that "GO" round with no rattle but to where it just plunks and falls out freely.

Now try the #2 round that just barely fit the chamber in your modified gauge to see what your new "over size" rounds will look like in the gauge.

This is all a fair bit of work and needs to be done with care to avoid flaring out or otherwise misshaping the gauge. But if you feel you know how to do it the upside will be a chamber checking gauge you can trust more consistently.

You MIGHT want to do a third such tester that is larger and won't quite fully seat in the barrel chamber. Mark that one with three file notches as "OVER SIZE". You can use that one to show you what any folded over or other wise misshapen ammo tests like.
 
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