Squib load experiment?

[bradhe]

Check my logic;  trying to get to the bottom of the potential danger of using reloads in my Thompson (M1).

Obviously to get bulged barrel you need a round with insufficient powder such that the bullet lodges in the barrel and then fire another, presumably full power round behind through human or mechanical action.

This can clearly happen of there is a squib and the human retracts the bolt, ejecting the now empty squib case and fires one or more subsequent rounds.  Clearly completely preventable if the barrel is checked after any suspect malfunction.

The question is whether anyone had done the experiment to see if it possible / likely to get a bulge from a squib by mechanical action?

When the gun fires, there are only 4 possible states:

1. Bullet exits the barrel and the bolt comes back far enough to feed/fire the next round...normal firing

2. Bullet exits the barrel and the bolt DOES NOT come back far enough to feed/fire the next round...you have a stopage but no barrel danger

3. Bullet does not exit the barrel and the bolt does not come back far enough to feed/fire the next round...this stoppage is fixable with a rod and mallet, but can lead to a bulge if the human retracts the bolt and attempts to fire again  (see above)

4.  Bullet does not exit the barrel but the bolt does come back far enough the feed/fire the next round (and perhaps several)...this clearly causes a bulge which is not preventable but the human.

The question is whether anyone has experimented enough to determine if #4 is possible?  The experiment is simple;  Load no/low power round in the top of the magazine followed by a dummy round.  Fire and see if the bullet exits and/or the dummy round is fed.  Try with no powder up small increments to full power loads.

Thought anyone?

Brad

[Dpedersen]

I reload 4.8 grains Winchester 231 with 230 RNFMJ and have no issues with cycling in my West Hurley. I think the book recommends a starting load of 5 grains. I load a little less to try to keep it a little cleaner when shooting. I wouldn’t really want to try to see how low I could go for fear of damaging the gun/barrel. It only takes one……

Edited August 13, 2023 by Dpedersen

[ppgcowboy]

I tried to see how low I could go at one time. I was at low 3.? grains of 231 when I stopped. All bullets exited and and it cycled. I may have been in the 2.something grains.

[Rudy]

My humble advice.  Don't go below the book recommended start.  It could actually be set off all at once and becomes a bomb.  More damage than an overcharge. Be careful with powder charges. 

[Dan K]

I agree with Rudy. Look up secondary explosive effect. More common in bottle necks than pistol rounds. There was a trend in the 70s to see how low you could go. More than one gun destroyed and guys hurt. 

My experience having reloaded for almost 20 years. Typically a squid primer no powder will lodge a projectile in the throat or forcing cone in a revolver. A brass rod will make quick work of extraction. Where I have seen bullets lodged part way down the bore is either light powder charges or contaminated powder.

If I have a stoppage and I do not cycle, I check for an obstruction with a rod. Cheap insurance.

[StrangeRanger]

I had a zero powder squib in a factory load (Maxxtech) in a Reising which has a much lighter bolt than a TSMG.  The primer alone did not cycle the bolt and the bullet was stuck in the barrel throat where it was easily removed.

[Sig]

12 hours ago, bradhe said:

The question is whether anyone had done the experiment to see if it possible / likely to get a bulge from a squib by mechanical action?

When the gun fires, there are only 4 possible states:

4.  Bullet does not exit the barrel but the bolt does come back far enough the feed/fire the next round (and perhaps several)...this clearly causes a bulge which is not preventable but the human.

The question is whether anyone has experimented enough to determine if #4 is possible?  The experiment is simple;  Load no/low power round in the top of the magazine followed by a dummy round.  Fire and see if the bullet exits and/or the dummy round is fed.  Try with no powder up small increments to full power loads.

Thought anyone?

Brad

Brad

i remembered and found this video of a Thompson firing and a blown barrel.  I could be wrong but I believe the video represents your #4 state. 

link to thread

video

 

[bradhe]

I have spoken to the engineers at a number of the component companies that publish data.  What I heard was that they aren't prepared to recommend very light loads because they have not tested them and fear liability.

I have seen from time to time stories of people blowing up handguns from "detonation".  All of the examples I remember (or could find on the internet) were 38 special bullseye wadcutter loads where it could not be ruled out that a double charge was involved.  To anyones knowledge that I have talked to, no one has every replicated the phenomenon in a controlled environment, though I would very much like to hear about it if anyone can point me.  At minimum it is very rare.

I have seen the video above.  It could very well be a number 4, but unfortunately the video doesn't show what happened immediately preceding so you can't be sure

[Sandman1957]

Not to steal this topic,  In the video also note that the weapon was NOT CLEARED!!  When it misfired, They should have immediately dropped the mag.  After cocking (and leaving the mag in place) I could not tell if they put the weapon on safe.  

Bottom line, when things like this happen please remember to drop the Mag, pull bolt to rear and put weapon on safe.  

[Motorcar]

I have seen a photograph of a Thompson barrel that started with one squib and many more stacked in on top of it. Then they did a side cutaway so you could see each round in the barrel on top of each other. Seems like 5 or 7 rounds in that thing. Probably posted here on this board ten or fifteen years ago maybe.

[bradhe]

Well that didn't take long.

Test #1 was 1 grain WW231 behind a 230g Zero JHP.  For 4 trials it handily fed the next round (which was a dummy) with the bullet stuck in the barrel (maybe a third of the way down.  With live ammo would have stacked bullets in a likely bulged barrel.  The #4 outcome is clearly possible/likely.

[rpbcps]

On 8/15/2023 at 4:13 PM, Sandman1957 said:

Not to steal this topic,  In the video also note that the weapon was NOT CLEARED!!  When it misfired, They should have immediately dropped the mag.  After cocking (and leaving the mag in place) I could not tell if they put the weapon on safe.  

Bottom line, when things like this happen please remember to drop the Mag, pull bolt to rear and put weapon on safe.  

👍Basic skills....from basic training in most armed forces. Although I have seen some piss poor weapons safety demonstrated over the years, in different parts of Africa.

[MrBill]

Years ago Gordon Herigstad had a Thompson Barrel that (based on barrel weight) had three bullets in it. At the SAR shows in Phoenix it was common to see bulged barrels on some of the tables. 

[StrangeRanger]

I recently pulled down some ammo that I loaded quite a few years ago.  I started by pulling one bullet to weigh the powder and confirm the load.  The powder was black instead of gray and there was verdigris on the base of the bullet.  I lit the powder and it did burn but slowly.  I ended up pulling all 100 rounds down and dumping the powder.  I knocked out the primers and there was verdigris present in many of the primer pockets.  Tossed the primers too.  I tumbled the bullets and the cases so they're ready for re-use.

If I had fired any of these and they had somehow ignited, I doubt that the bullet would have made it out of the barrel.

Lessons learned:

1. There's a reason that the military seals their primers and case necks and/or uses sealed bulk packing
2. Long term ammo storage, especially of re-loads, even if stored in normal conditions may not be a good idea

[Rekraps]

On 8/13/2023 at 6:42 PM, bradhe said:

Check my logic;  trying to get to the bottom of the potential danger of using reloads in my Thompson (M1).

Obviously to get bulged barrel you need a round with insufficient powder such that the bullet lodges in the barrel and then fire another, presumably full power round behind through human or mechanical action.

This can clearly happen of there is a squib and the human retracts the bolt, ejecting the now empty squib case and fires one or more subsequent rounds.  Clearly completely preventable if the barrel is checked after any suspect malfunction.

The question is whether anyone had done the experiment to see if it possible / likely to get a bulge from a squib by mechanical action?

When the gun fires, there are only 4 possible states:

1. Bullet exits the barrel and the bolt comes back far enough to feed/fire the next round...normal firing

2. Bullet exits the barrel and the bolt DOES NOT come back far enough to feed/fire the next round...you have a stopage but no barrel danger

3. Bullet does not exit the barrel and the bolt does not come back far enough to feed/fire the next round...this stoppage is fixable with a rod and mallet, but can lead to a bulge if the human retracts the bolt and attempts to fire again  (see above)

4.  Bullet does not exit the barrel but the bolt does come back far enough the feed/fire the next round (and perhaps several)...this clearly causes a bulge which is not preventable but the human.

The question is whether anyone has experimented enough to determine if #4 is possible?  The experiment is simple;  Load no/low power round in the top of the magazine followed by a dummy round.  Fire and see if the bullet exits and/or the dummy round is fed.  Try with no powder up small increments to full power loads.

Thought anyone?

Brad

Brad, intriguing post. I thought about this a bit (I have had a squib in a .45/70 (Marlin 1895) using range reloads. Never had a squib on a semi-auto gun, and certainly never using a MG. Part of the reason is that just because I fear reloads with respect to any potential savings on the cost vs the cost of the rifle or MG, I exclusively use military surplus ammo... for all my guns OR well known commercially produced ammo. 

That being said, if the charge is not sufficient to drive the bullet out (assuming a correctly sized bullet of course), then it seems that it would also not be sufficient to drive the bolt rearward sufficiently so as to feed and chamber another round. Action and reaction type of thing. I have never heard of a squib on a fully and properly loaded round so the answer has to be improper powder load. Thus my opinion that scenario 4 cannot ever happen. 

I guess I need to think about this more. I also shoot plenty of subs and the trick with them is to get just sufficient powder to drive the bullet AND work the action. There are plenty of posts about this and the problem of using subs in semi-automatic or SMG's. 

The most likely cause of most of the squib events is scenario 5. Bullet does not exit the barrel, obvious squib, shooter manually cycles the action loading another round and BANG... gun is damaged.

[bradhe]

Rekraps:  I agreed with your logic, but see my post above on the actual test

Brad

[Rekraps]

16 hours ago, bradhe said:

Rekraps:  I agreed with your logic, but see my post above on the actual test

Brad

Thanks... I'm shocked.  That should not happen.  Wow, I wonder then why with all the zillions of rounds shot there are not more squib incidents with SMG's?

[Ivan]

 

"'Thanks... I'm shocked.  That should not happen.  Wow, I wonder then why with all the zillions of rounds shot there are not more squib incidents with SMG's?"

Why would it not happen ?

Squib load lodges bullet in barrel. Barrel is plugged solid at that end.

Pressure has only one direction to go. Back towards the bolt.

Not enough pressure to push bullet out but just enough pressure to kick the bolt back, maybe just enough to pick up another round, open bolt F/A so as soon  as the bolt is forward the gun fires.

As for using reloads. I use my reloads. Been reloading ammo for over 50 years and the main things are use good components, PAY ATTENTION when throwing powder and only have one type of powder on the loading bench.

I NEVER use other people's reloads. As for surplus ammo, only use clean known quality surplus. It amazes me to see someone use crap, 3rd world manufactured surplus ammo in expensive weapons. Like old Turkish 8mm in a Transferable MG42 ! 

[DINK]

So are the tests going to continue?  I am curious to see what level of powder is needed to get the bullet clear of the muzzle.  That would help define the "danger zone" which would result in a blocked/bulged/burst barrel.  

[bradhe]

Sorry, I wasn't planning on continuing.  Got my answer and just ordered 10 cases of S&B.

I do now have 12k rounds of ammo for my LWRC MSG though.....

[DINK]

OK, thanks for sharing the results that you did get.