Got a surprise yesterday!

[Barry54]

I tried out my new to me lube/sizer and was excited about having loaded rounds that weren’t sticky with LLA. The lube in it is soft and tacky but I’m thrifty and using it and learning.

I’ve been making little substitutions for years. How many times do you find the exact bullet in a recipe with the powder you want to use? Anyway I set out expecting a mild to weak load with the starting charge.

Here’s where I deviated. I seated a little bit deeper than the minimum oal in the recipe. I substituted my home cast tc profile boolet into data for a round nose. I figured the blunt truncated cone shape could be seated deeper than a round nose, so I should be good. Until I wasn’t...

So I’m fortunate I’m unscathed. Praise the Lord!
Be careful, and wear safety glasses, especially when testing a new load.

[nwilson1024]

Damn… I do that same thing quite often as well. I wonder how on the edge I really am. I can check velocities but pressure is the devil in the details.

[dverna]

Something else went wrong. If you expected a mild load and that happened, it bears more investigation. You would have to seat the bullet quite deeply to cause a large pressure spike.

Glad you did not have a more serious result...and yes wear eye protection whenever shooting.

[Barry54]

I admit to using a fast powder and smaller charge getting more rounds per pound.

So day one of lubrisizer. Got some lube on the base of the boolets. Wiped it off with a paper towel, because I didn’t want it contaminating the powder. I’ve heard of a “diesel effect” with putting Vaseline in the cup of air gun pellets which acts as fuel and increases velocity. I doubt that there was enough exposed lube in this instance to be a fuel, but it’s the newest variable I’ve introduced.

[beemer]

Yes safety glasses, you only have one shot at this. Always wore prescription safety glasses, got my eyes fixed and still will not shoot without something on. Glad you are ok. What pistol and how did it fare?

I don't load the 9mm a lot but do start low and creep up. Tinkering with the 32acp and 9mm I learned that cases with small powder capacity and higher working pressure can go sideways in a hurry. I check how deep the bullet is in the case, capacity is already small and it doesn't take much to make big changes.

[Markopolo]

I wonder if this isn’t a case issue, and not a lube or bullet problem.. something ain’t jiving.. I would suggest trying it again… I know, sounds crazy… but it doesn’t look like a pressure spike. You could setup a remote fire. But what the heck do I know.. how about more details about the exact load and bullet?

[Barry54]

9x19
I looked at a recipe from the Vihtavuori app with a recipe for a 145 grain H&N plated round nose. 2.6 grains of N310 powder. (3.3 max) 1.142” oal. Predicted velocity of 794 FPS.

I assembled 2.6 grains N310 powder and a Lee 147 grain boolet at 1.058” because it looked closest to the 147 grain in the Lyman manual and they used that length. I didn’t want interference with the boolet sticking out in firearms with a short throat, and was planning on a one size fits all, general purpose plinking round. I tested in a blowback ar 9 carbine. It sooted up the top of the magazine and blew it on the ground. No damage upon a quick inspection, besides skid marks in my underwear.

And for another point of reference, I was loading a 200 grain boolet last week with N310 with charges between 1.2 to 1.5 grains.

[Super Sneaky Steve]

Something else went wrong. If you expected a mild load and that happened, it bears more investigation. You would have to seat the bullet quite deeply to cause a large pressure spike.

Glad you did not have a more serious result...and yes wear eye protection whenever shooting.

I agree.

To me it looks like the case was extracted before pressure dropped enough causing the case to rupture at the base where there was no support. Just a guess. A blowback weapon won't have any kind of lock so maybe the weight of the bolt doesn't match the heavier 147 boolit.

[Barry54]

I don’t think the 147 grain bullet weight is incompatible with the carbine. As a matter of fact, I took a whitetail with a 147 grain XTP several years back. I’ve used 115 through 200 grain projectiles previously.

Premature extraction is a thought. But I haven’t mechanically modified anything from a former working condition.

[Barry54]

I noticed the rounds don’t “plunk” when I was attempting to get this photo.

Now I’m thinking maybe it fired slightly out of battery?

[jdgabbard]

I was at the range a while back with my 9mm SBR, see below, while shooting my 115gr load (4.2gr Red Dot @ 1.115" OAL - I've since reduced this to 1.110" OAL which doesn't have this issue) I suddenly what could best be described as a snap with a fizz. Knowing something was off I unloaded the rifle and began checking things out. Basically, what happened is the OAL was just a little long, and the bullet jammed in throat of the barrel, causing an out of battery detonation. Everything was good, but the rifle was out of commission until I got a wooden dowel to knock out the bullet and the end of the case once I got home.

This stuff happens....

[Barry54]

I scraped these pieces of lead from the end of the chamber. They were exactly where the cartridge headspaces.

[Dusty Bannister]

Do you think that if the bullet is seated out too long and is not chambering easily, when the cartridge is fired, the gas pressure expands the base of the bullet before the heavy for caliber bullet begins moving? You seem to have a lot of variables before this "aw shucks" occurred.
Bullet diameter, any nose clearance, correctly chambered round, did the primer back out or just blow the side of the case? Last time the chamber was scrubbed out?

[FISH4BUGS]

A firing out of battery will produce the same thing.
I would consider that before anything.
I had a Smith 76 open bolt subgun that would do that on occasion, even with HOT loads!

[Barry54]

Rupture resolved! Get the lead out!!!

Cartridges plunked in the Lyman cartridge checker. Cartridges plunked in the barrel after picking out the lead. Went back out to the range and chambered one of the suspect rounds. Pulled the rear take down pin and verified the bolt was all the way forward. Fired a round with no issues. Fired the last three rounds of the test batch as well.

This is still likely a hot load due to the fast powder and seating depth. I need to dig out some factory ammunition and compare pressure signs, and go from there.

Thanks again to all of you for your help!

[rintinglen]

Something else went wrong. If you expected a mild load and that happened, it bears more investigation. You would have to seat the bullet quite deeply to cause a large pressure spike.

Glad you did not have a more serious result...and yes wear eye protection whenever shooting.

In a 38 Special, an eighth of an inch was enough to nearly double the pressure of a 2.7 Bullseye load. This was researched by Hercules back in the 70's after a blowup or three in police revolvers using reloads for qualification. https://americanhandgunner.com/1982issues/HJF82.pdf

The 9mm is even more vulnerable as the boiler room is less than 2/3rds the size of the longer 38 round, while it runs at pressures that start at the very top end of 38 special +p. Additionally, 9mm case capacities run all over the place. Brass thickness varies markedly from manufacturer to manufacturer. Thus a case with thicker brass might crimp just fine while a lighter case with thinner case walls might not. A comparatively minor amount of set back in a 9 mm can lead to exciting times.

My personal guess is that there was a slight out of battery condition resulting from the lead build up in the chamber, a somewhat loose boolit in the case, a bump from the feed ramp and a little more of push back from the lead build up all combining to increase the pressure while at the same time reducing the support to the case head. But I'm glad nobody got hurt.

[Barry54]

Amen!

[fredj338]

I did some vel testing with upper midrange loads & diff seating depths. Both in 9mm, 147gr using WST & Unique. I reduced OAL by 0.010" & fired 3 rds. I found no significant vel increases until I seated 0.060". All things being equal, increase in vel is an increase in pressures too. So I am not sure a very small OAL reduction of 0.005" would affect anything. To the OP, more likely the longer bearing surface of the TC + shorter OAL + possibly a poor piece of brass caused your case head blowout.

[Barry54]

9x19
I looked at a recipe from the Vihtavuori app with a recipe for a 145 grain H&N plated round nose. 2.6 grains of N310 powder. (3.3 max) 1.142” oal. Predicted velocity of 794 FPS.

I assembled 2.6 grains N310 powder and a Lee 147 grain boolet at 1.058” because it looked closest to the 147 grain in the Lyman manual and they used that length. I didn’t want interference with the boolet sticking out in firearms with a short throat, and was planning on a one size fits all, general purpose plinking round. I tested in a blowback ar 9 carbine. It sooted up the top of the magazine and blew it on the ground. No damage upon a quick inspection, besides skid marks in my underwear.

And for another point of reference, I was loading a 200 grain boolet last week with N310 with charges between 1.2 to 1.5 grains.

I loaded a few more since I figured out the debris/headspace issue. I increased the oal from 1.058” to 1.070” in an attempt to reduce chamber pressure. I didn’t want to go any longer, due to exposing the upper lube groove.

Vihtavuori predicted 794 FPS at 2.6 grains in a 4” barrel.
I averaged 805 FPS from a 3” barrel.

I guess I’ll have to wait for a micro-disk to arrive in the mail, since the smallest normal disc orifice of 0.3cc drops 2.6 grains.

To be continued...

[GONRA]

Barry54 sez: "I noticed the rounds don’t “plunk” when I was attempting to get this photo".
GONRA sez: "That's It! !! Next tyme, PLUNK TEST ALL product
(not just a SAMPLE !) before shootin' 'em all up.......

No matter HOW CAREFUL you reload and how glorious
yer RELOADING HYGIENE is, SOMEHOW, SOMETYME
yer gonna screw up and FAIL the **** plunk test !!




a bad round shows up.
You can beat yer brains out

Iw all a Great Mhyseery".