What happened?


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brokencowboy
April 30, 2008, 05:49 PM
I was trying to work up a load for my S&W model 21 .44 Special using IMR's PB powder. I was shooting my last string of 6 rds. using my chronograph to check the bullet velocity of the different powder charges I had made. The first four I shot were disappointing, only pushing the 240 gr bullet at about 560 fps. Then fifth round clocked in at just over 300 fps. When I touched off the sixth round, that's when something weird happened. There was a loud KABoom & the gun almost jumped out of my hand from the recoil. When I checked the chronograph, the reading was 1128 fps. I tried to eject the eases & one was so streached that I had to use my squib rod to push it out of the cylinder. I checked the cylinder, frame & barre1 for any signs of cracks, swelling ect. To be sure the gun was still working, I loaded six rounds of my carry ammo & fired them through the chrono & they were clocking at previously tested speeds, so I think the gun is okay.


What I don't understand is why did I get such a light load followed by what appears to be a double charge. I have been loading for over 10 yrs. & have never run into a situation like this. I use a Dillon 550 press & these rounds were the last of a set of test rounds I had run for this test. I used an Ohaus 1010 scale to check the powder drop in setting up the load, then checked about every fourth case to make sure the weight was right. If anyone out there have any ideas, any comments would be appreciated,

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Mr White
April 30, 2008, 05:52 PM
...then checked about every fourth case to make sure the weight was right.I guess the double charge was in the third case. :eek:

I've only been reloading for about a year and am extremely careful when throwing powder. I missed a charge a few months ago and it really woke me up to the fact that no matter how careful I think I am, I can never be perfect. Perfection is just contrary to human nature. (except for my wife's nature, just ask her.)

FieroCDSP
April 30, 2008, 06:29 PM
Sounds like the powder for the weak shot hung up in the drop tube somehow. It dislodged into the over-charged one. Bang, bang, pop, BOOM!! Yeah...your powder hung up. I think there's a powder check die you can put in the press to help prevent this. Careful monitoring of your cases before seating the bullet is the only other way to prevent such an issue.

loadedround
April 30, 2008, 07:48 PM
Sounds like the classic double charge to me.

redneck2
April 30, 2008, 07:57 PM
Then fifth round clocked in at just over 300 fps. When I touched off the sixth round, that's when something weird happened. There was a loud KABoom & the gun almost jumped out of my hand from the recoil. When I checked the chronograph, the reading was 1128 fps.

Seems pretty simple. The powder that was meant for the fifth round (300 fps) got hung up in the powder measure and dropped in the sixth round (1128 fps).

The other answer may be that the fifth round didn't actually clear the barrel. I have doubts that anything 300 fps would squirt out. It may have stuck and the pressure of the following round forced it out. Once I saw a .45 acp that had a squib followed by a round exactly as you described. Pushed both out.

oldgold
April 30, 2008, 09:46 PM
I vote for powder bridging. My Dillon did it to me with PB. Moisture or static electricity. Don't leave PB in your measure overnight. It tends to clump up.........Also discolors the drop tube.

brokencowboy
April 30, 2008, 09:55 PM
Thanks for all your advice & suggestions.

I have seen the results of a double charge & am very careful to avoid such. I wish I could afford to purchase powder check devices but living on a fixed income makes that very difficult right now. I'm just glad my S&W withstood the event,

mek42
April 30, 2008, 09:57 PM
The other answer may be that the fifth round didn't actually clear the barrel. I have doubts that anything 300 fps would squirt out. It may have stuck and the pressure of the following round forced it out. Once I saw a .45 acp that had a squib followed by a round exactly as you described. Pushed both out.

I don't use a chronograph yet, but doesn't the fact that the OP got a 300 fps reading imply that the bullet left the barrel?

rcmodel
May 1, 2008, 02:32 PM
You are indeed fortunate that a double-charge Cowboy Action load of PB in .44 Spl. turns out to be about the same as a max load of PB in .44 Magnum.

Thank your lucky stars you were shooting a strong S&W 21, and not some lesser gun like a Charter Bulldog!

rcmodel

DEDON45
May 1, 2008, 02:44 PM
This one of the reasons I prefer a 5 station press, so I can put a powder cop or lockout die in... double charges (or squibs if someone's not listening for them) scare the Bejeezus out of me... haven't had one happen to me yet (knock on wood)... yeah, I think your powder got bridged in the measure or drop tube, and dumped double (or more) powder in the case. Glad you're OK, and glad you were shooting a strong gun... I guess you just ran a "proof" load through it!

ranger335v
May 1, 2008, 02:46 PM
Sorry that your handgun was damaged and glad you weren't hurt but what you have experienced is exactly why I never had any desire for a progressive type press, I just don't need speed more than I need safety. As you noted, spot checking every X number of rounds offers little security.

With my single stage, I charge a full tray of primed cases at once and then visually check the consistancy of the powder level in EVERY case before moving to seating. For over 45 years and counting, never had a blooper or BOOMER!

redneck2
May 1, 2008, 06:56 PM
I don't use a chronograph yet, but doesn't the fact that the OP got a 300 fps reading imply that the bullet left the barrel?
Depending on the placement of sensors, the pressure wave may register. Perhaps unlikely, but I was trying to put all options on the table. 300 fps is about twice what a pitcher throws a fastball. Not much for a bullet. From what I've read, anything below 550-600 fps is subject to plugging the barrel.

Walkalong
May 1, 2008, 07:11 PM
Arghhh

brokencowboy
May 1, 2008, 08:12 PM
I went back in the shop today & set up the press to see if I could cause a situation that repeated what happened yesterday. Everything was the same down the brass. I had empty cases in the sizing & crimp stations. I threw 25 charges & weighed each one.

Most of the throws were right on the money, though some were off by % .1. However, two throws were definity light & the throw behind the light ones pegged the lever as being over weight. The Dillon powder measures have baffles in them to stop power compression, thus, right now, I have to look at the powder. After this little test, I know I'm going to have to be more selective in my powder choices & more observant about how the case is charged.

I appreciate all your comments & help in trying to find a solution to this problem. At the present, I'm getting about 675 fps w/ 4.9 gr of 700-X.

brokencowboy
May 1, 2008, 09:58 PM
If any of you are interested in who you've been writing to, you can see me at the at the website listed below.

http://picasaweb.google.com/home?tab=mq

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