9MM Kaboom Yesterday

[carbine85]

I was shooting the AR9 yesterday with a new load and had a Kaboom.
Turns out the round wasn't seating all the way into the chamber properly leaving the end of the case unsupported. The rifle is repairable and should be GTG.

The case stuck in the chamber.

The chamber appears to be okay.

The blown out case and a couple that almost kaboomed.

Factory round on the left, Kaboom reload in the middle, and deeper seated bullet on the right.
I figured out that the round has to be seated at 1.09" for the bolt to close properly. The shape of the bullet won't allow it to chamber if it's any longer.

 

[carbine85]

This is the damage done by the kaboom.

I already repaired the mag block and inspected all the parts. Everything looks GTG.
I'm glad I had my glasses on. I got face full of small debris and smoke.

 

[stlcards]

Glad you didn't get hurt, or have any major damage. I'm sure you're down a pair of underwear as well, at least I'd be!

 

[bbqreloader]

Carbine, did you build yours and if so did you use an insertable mag block? Thinking of building one, but still researching the magazine issue. I like New Frontier's lower because I can use glock mags.
Glad you are ok, the weapon can always be fixed.

 

[Walkalong]

Wow, you need to figure out what is going on there.

 

[boom boom]

You need a check gage for your ammo even commercial can be out of spec. An out of battery detonation is as bad as it gets.

 

[carbine85]

Carbine, did you build yours and if so did you use an insertable mag block? Thinking of building one, but still researching the magazine issue. I like New Frontier's lower because I can use glock mags.
Glad you are ok, the weapon can always be fixed.

Yes, I built this one. I used the Spinta mag well block and a Faxon barrel.

Wow, you need to figure out what is going on there.

It was an out of battery detonation. The back of the case wasn't supported. The shape of the bullet prevented it from chambering all the way.
The OAL was 1.13. After inspection I realized that it requires 1.09 Max OAL to chamber properly.
The factory round (silver case) is 1.13 and it chambers properly. I was trying to duplicate that round

 

[ReloaderFred]

The longer shank of the reloaded bullet was jamming into the leade, which caused the out of battery discharge, as you've already figured out.

I recently ran into this same problem when loading Remington 124 gr. JHP bullets for my 9x19 Olympic Arms AR upper. The longer bearing surface, and resulting shorter ogive, of the Remington bullet required deeper seating for the round to fully chamber with the bolt closed. I checked mine for chambering before I fired any, though. Mine uses 32 round Bren Gun magazines, which requires an adaptor to be used in the standard .223 lower.

Hope this helps.

Fred

 

[Salmoneye]

Forgive me, but I am not familiar with the AR9, nor AR's in general...

How is it even possible to fire a round that far out of battery, let alone repeatedly?

 

[carbine85]

Forgive me, but I am not familiar with the AR9, nor AR's in general...

How is it even possible to fire a round that far out of battery, let alone repeatedly?

The AR9 is a blow back action and doesn't have the locking lugs like the AR15.
I'm a little surprised by this myself. I don't the AR15 would do this. In this case it was close enough for the hammer to strike the pin.

I forget to mention the load: 147 gr Hornady JHP, 4.3 grains of Titegoup, Winchester primer.

 

[LiveLife]

Wow, you need to figure out what is going on there.

147 gr Hornady JHP, 4.3 grains of Titegoup

4.3 gr is over published max charge. Hodgdon lists 3.6 gr as max charge with 1.100" COL - http://www.hodgdonreloading.com/data/pistol

147 GR. HDY XTP Titegroup COL 1.100" Start 3.2 gr (855 fps) 22,500 CUP - Max 3.6 gr (929 fps) 27,500 CUP

OAL was 1.13. After inspection I realized that it requires 1.09 Max OAL to chamber properly.
The factory round (silver case) is 1.13 and it chambers properly. I was trying to duplicate that round

With any new bullet, I always determine the max OAL/COL using the tightest barrel with shortest leade and then determine the working OAL by feeding/chambering dummy rounds (no powder/no primer) from the magazine. With 115 gr HAP, I used 1.075" OAL - http://www.thehighroad.org/showthread.php?p=10358518#post10358518

I already repaired the mag block and inspected all the parts. Everything looks GTG.

How did you repair the mag block?

I built several AR carbines with mag blocks and found the bullet nose could hit the feed ramp at the front of the mag block pretty hard if not fed at proper angle from the magazine.

To ensure the feed ramp returned to original position and feed angle, before you do any live fire, I would:

1. Check the magazine lips/follower for any deformation/damage.

2. Function test for reliable feeding/chambering from the magazine using dummy rounds.

3. Measure lengths before and after feeding from the magazine to check for any bullet setback.

4. If you are using mixed range brass, I would test and measure several samples of each head stamp.


Keep in mind that with significant bullet setback, we have seen KaBoom/overpressure situations even when using below max load data.

I'm glad I had my glasses on. I got face full of small debris and smoke.

Thank goodness you didn't suffer any serious injury.

 

[CZ9shooter]

You didn't plunk test your load?! I hope you have learned a lesson.

XTPs generally need to be seated quite deep. Some guns can get away with a longish OAL, but there is a reason the manuals call for them to be so short.

 

[LiveLife]

Thinking of building one, but still researching the magazine issue. I like New Frontier's lower because I can use glock mags.

I have PSA carbines with mag blocks and Just Right carbine that uses modular mag wells with Glock magazines (can also use M&P/1911 magazines with mag well swap).

If you have the option to go with dedicated lower that uses Glock magazines, you will experience less feeding/chambering issues but most do not have last round bolt hold open feature.

After much research regarding different mag block and magazine brand feeding issues, I decided to go with PSA carbine kits that use hybrid ramped bolt and mag blocks fit very snug without any play in Anderson/S&W M&P15/Spikes Tactical lowers. AR Stoner magazines with 4way anti-tilt follower and coated stainless steel body (for high rust coastal area I live in) have worked well with different profile bullets and last round bolt hold open works well - http://www.midwayusa.com/product/2228167977/ar-stoner-magazine-ar-15-9mm-luger-stainless-steel-black

 

[Walkalong]

Wow, you need to figure out what is going on there.

It was an out of battery detonation. The back of the case wasn't supported.

My bad for not stating the obvious.

The shape of the bullet prevented it from chambering all the way.
The OAL was 1.13. After inspection I realized that it requires 1.09 Max OAL to chamber properly.

Glad you figured that out. I guess you skipped the plunk test.

I forget to mention the load: 147 gr Hornady JHP, 4.3 grains of Titegoup, Winchester primer.

As already pointed out, that is over the Hodgdon online data. How did you arrive at that charge weight? It certainly didn't help.

 

[bbqreloader]

bds and carbine, thanks for the info.

 

[carbine85]

I have several recipes that show 4.3 as the max load. The round is too hot and I was working up the loads too fast. I went back and checked my notes. I've used the same bullet in the past but seated it at 1.09.
I use gauges for the 5.56 and .308 so I guess I'll get one for the 9MM.

 

[Walkalong]

I use a Wilson case gauge for 9MM. If a normal sizer won't get it to fit the gauge, I scrap it. I lose 10% or so of range brass doing this. I figure they have been over stressed and even if a push through (Bulge buster) sizer will 'fix" them, I have too much 9MM brass to worry with them. I picked up another 200/300+ today.

 

[rodregier]

For those that are only recently in the reloading game, using just a cartridge gauge to check (re)loaded ammunition doesn't check everything. Most gauges don't check the equivalent of "leade" of the chamber(s) you will be using.
(Kind of like a funnel at the end of the chamber for the transition into the rifling).





It is very important to ensure correct OAL which avoids jamming the ogive of the loaded projectiles into the chamber leade of a specific firearm.

I've loaded 9mmx19 for various firearms. There is an enormous variation in the chamber leade dimension of barrels, including different generations from the same manufacturer.

This is especially critical in blowback actions, since the designs typically don't have merchanical interlocks to avoid firing out-of-battery.

 

[higgite]

Rodregier is absolutely right. I have loaded rounds that passed a Wilson Pistol Max Gage like the one pictured in post #17 with flying colors only to fail miserably when plunk tested in a stock CZ pistol barrel.

 

[Walkalong]

I only use the gauge to check sized brass. I use the plunk test to make sure they fit the chamber, but I don't load long, I pick OAL in autos for function.

 

[Duvel]

Case gauges are handy for checking to see if there are any 'case' issues, but only your actual chamber will give you a go / no-go for oal.

 

[forrest r]

Hello everyone, 1 heck of a topic for a 1st post!!!

Something to look for with semi-auto reloads, the bullets shoulder. Typical chambers for semi-autos are cut with + 20/1000th's of freebore before the throat starts.

If you look at the op's reloads you'll see a huge amount of the bullets shoulder sticking above the top rim/lip of the case when loading semi-auto ammo.

You will have problems.

Typical reloads and the shoulders of the bullets in relaotionship to the top of the case.

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The bullet/reload on the lower left is a 45acp with a h&g #68 200gr swc bullet. Countless 1000's of reloaders have used that bullet for target loads in their 45acp's sending 1,000,000's of bullets down range. The gold standard is a oal of 1.250" with a .469/.470 crimp.
If you load those bullets and the oal is not 1.250 that's telling you somethings wrong with either your bbl's chamber (AFTER PLUNK TEST) or your dies are off.
The other bullets like the top right is nothing more than the lee 125gr tl truncated coned 9mm bullet that I removed the tl grooves from the mold and pc'd the bullets. As you can see the bullets are seated to the top tl groove or 20/1000th's of the bullets shoulder are sticking out of the case.
Same with the other 2 reloads, you can see the shoulder of the bullet and how far above the case that shoulder is.

What the bullets shoulder is actually hitting:
Firearms mfg's are starting to skip 1 step in the bbl making process. Namely the throating of the bbl. A factory bbl that was shipped for you to use that hasn't had a throating reamer used in it. Note the chambers there, the step into the throat is there. Then there's just a sharp angle (note the sharp angle on the riflings) to center the bullet. When that "throat or lack there of" area is that small/sharp the bullets oal becomes allot more important. To long and the bullets shoulder hits that reduced area (sharp angled area past the 20/1000th's freebore) and either keeps the bullet from fully chambering or the bullet will be jambed back in the case causing bullet setback. Either way it's not good!!!


The same bbl after it has had a throating reamer used it it. Note the longer more gradual taper of the throat into the riflings. This process opens the area where the 20/1000th's freebore ends and the throat begins. The shoulder of the bullet aligns better to the bore and doesn't a shape angle to be jammed into.


1st throat picture ='s no throat/typical mfg offerings
2nd picture ='s a standard throat in a semi-auto pistol bbl

This is what a nm bbl's throat looks like. It has an extremely long taper that is highly polished. The idea is that the bullets are centered to the bore with the least amount of damage.

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All 3 bbl's have the same freebore (around 20/1000th's). The throated bbl's are just more forgiving.

On a side note:
I don't know if the op is seating and crimping in the same stage??? The reloads he pictured they have vastly different oals (center vs right). If you take a good look at that factory round (left) you can see the bullets body tapering before it even gets to the shoulder making that area smaller than the bullets being used for reloading.

 

[carbine85]

On a side note:
I don't know if the op is seating and crimping in the same stage??? The reloads he pictured they have vastly different oals (center vs right). If you take a good look at that factory round (left) you can see the bullets body tapering before it even gets to the shoulder making that area smaller than the bullets being used for reloading.

The round on the left is a factory loaded round that will chamber, the middle round is one of the rounds that's too long for that bullet, and the one on the right is the length it should have been in order to chamber properly.