please share your (bad) experience using underpowered loads

[Larry Gibson]

Had a Silhouette S&W 29 44 mag I had just purchased. Won a pound of AA#9 at the silhouette matches. Decided to try it in the 44mag with 295gr SWC boolits.
Had 13 pieces of new brass, so loaded what I thought would be a good starting load, weighed each charge and once done , inspected cases/powder in the loading block for uniformity, then proceeded to seat boolits.
Went PD hunting with friend. Took 6 shots to check for grouping, which did very well. Got our rifles out and shot a bit, took a break for some Gatorade and saw a few PD's about 100yds. Loaded gun with three rounds. First shot missed, second shot the same, third shot there was a pinkish flash, mild recoil, and I couldn't see the PD due to the top strap sticking up at about an 80 degree angle. Top 3 chambers of cylinder gone, but empty cases still in the gun, one split others bent. Friend heard something whizzing by him(probably cylinder piece) and the sight elevation piece that fits in the frame was down my t-shirt. Never found the sight.
Double charge?? Not a chance!!!
Load was way too light!!

Classic SEE; fired the first 6 shots ok. That fouled the throats/forcing cone. Then the fouling probably hardened in the warmer weather while you shot PDs with the rifle. Then on the third round the powder was probably at the base of the bullet from the recoil of the first 2 shots. The primer flash pushed the bullet into the forcing cone where it stuck sealing off the barrel/cylinder gap also. Because the powder was also pushed forward into the cylinder throat it didn't ignite properly but smoldered but when the bullet stuck it started to burn. Before the bullet could get moving again the pressure reached a catastrophic level which the cylinder could no longer contain.

It does happen......

[PrestoColumbus]

What you had or were close to having was an SEE (Secondary Explosive Effect). Some refer to it as a "Pressure Excursion".

Smokeless powders do not "detonate" in cartridges, they burn. How and when they burn is the problem.

The cause of SEE is well understood since the advent of piezo-transducer and strain gauge pressure measuring since the '80s. There is an excellent explanation that was published in a Handloader article which I have posted here numerous times. An SEE can easily be reproduced pretty much "on demand". Being able to measure the pressure, observe the Rise to peak pressure and the time pressure curve/trace has allowed me and others to observe the potential SEE before it occurs.

All of the old theories (which are/were not reproduceable) may have sounded good but they were not the actual cause of an SEE.

What actually occurs is a series of conditions (not all the conditions need be present) lead up to the root cause of an SEE....a bore obstruction. Seldon does an SEE occur with just one or two shots. It usually will occur with shots three through 10 +/-. In the case of your AR with that reduced load of H110 the force of the primer pushed the bullet into the probably already fouled throat/leade/bore where it stuck because the powder had not yet begun to burn. Then the powder began to burn and it reached excessive pressure before the bullet began moving fast enough to lower the pressure from the expansion ratio as the bullet moved down the bore. SEE's do occur with cast bullets but usually the bullets begin moving because cast are softer than jacketed. Fortunately for you, the cast bullet began moving before the pressure really got high.

All this occurs very quickly, in milliseconds, and is usually not noticed. However, sometimes a "click/bang" effect is noticed. That is an omen of potential SEE and any time a click/bang occurs you should stop using that load.

Over the last 50+ years I have been directly involved with a couple SEE's that actually did destroy the firearm. I also have been involved in several probable SEE's and have investigated others that were found to be probable SEEs. I also have on several occasions while pressure testing loads observed the buildup of pressure that leads to SEEs. I stopped testing before the SEE occurred.

You are absolutely correct sir.

Going back thru my records…. this was July 2021

I had several rounds loaded with 6.7gr H110 (looking back that was kind of stupid but at the time i didn’t know all this) and 225 gr Berry’s Spirepoint .308 in a 300AAC cartridge with small rifle (not magnum) primer

6 rounds fired over chrono (~800-850 fps)
afterwards I did observe some strange scratches on the hulls (debris in chamber?)
none cycled the rifle (DPMS rifle with 16” barrel)

round #7 was the problem
- i felt a sharp recoil
- BCG did not cycle into the buffer
- smoke/soot coming out of every place it could find, even found soot shoved down into the magazine
- myself and several others tried in vain to pull the bolt back but could not extract the spent case
- we did record a reading on the chrono for the boolit in the 700 range (was lower than expected)
- gunsmith had to remove barrel to get the case out, found bolt face was disintegrated and had to replace that
- i still have not attempted to fire this weapon again as i think the chamber is damaged and i want another gunsmith to look at it

bottom line: i’ve learned a value lesson that i’ll never forget. i’m lucky i didn’t end up seriously injured. and much better/cheaper to ruin my rifle and buy new one than to end up in the hospital

thank you for sharing your opinion from the technical viewpoint. it very much lines up with my experience

There’s a saying we have, “sometimes you see something so stupid you know a Marine has to be involved…” I’ll take the hit on this one! (well, i already have)

[KCSO]

Not mine but... My ex son in law borrowed my smith 5906 and went plinking with a friend who whipped up some ammo for him. The third round was a squib lodged in the barrel and number four fired quickly bulged the barrel about midway and ruined the barrel and was absolute heck to remove without damaging the slide. Then he took my daughters Charter snubbie and fired some more of the defective rounds and blew out the side of the cylinder. Then he got drunk and gambled away all their money, but that is another story.

[megasupermagnum]

"I have heard underpowered (not enough powder) loads can be as dangerous as overpowered loads'

No, underpower loads are WAY more dangerous than overpower loads. Obviously if you do something extremely dumb, you can over charge a cartridge to failure. You could probably load enough Unique in a 44 magnum to blow up the gun, but I still wouldn't bet money on it. Using sane powders like Bluedot, 2400, H100, etc. you would have to try your absolute best to blow up a 44 magnum. This carries over to most any cartridge's, at least for modern guns.

On the other hand, look at the plethora of ways in this thread underpower loads can ruin guns, even with experienced loaders have. My only issue was using very light charges, ended up double charging one. Thankfully a double charge was still well under a max load. Light loads are one thing, but the super light poof loads are not something to dink around with. They are serious business, way more dangerous than over charges of regular powder.

[Woodcarver]

I watched a gent blow up a beautiful nickel plated Colt 45 SAA with an undercharged round at a SASS match in the late 90s. IIRC, his "standard" load was 4gr of either Titegroup or Trail Boss under a 250gr cast FP. As we were counting hits, and he was a decent shot, we know the first round went down range. Then his second shot sounded "funny". The RO heard it and immediately called cease fire.
The top strap was severely bowed. The top of the cylinder on either side of the chamber fired was gone. The other live round was squeezed by the cylinder distortion and the bullet was wedged against the frame. The fired chamber had wedged the bullet partially into the forcing cone and blew the sides into the adjacent chambers. We think that is what blew the tops off those chambers.
He pulled about 10 bullets from his ammo supply and found several that only had about 3-3.5gr of powder. He used a progressive. At 4gr, he was below the recommended charge; at 3-3.5, he was way below. Trying to cut recoil down to improve times cost him a $1600 Colt.
Smokeless powder does burn, but when all of it burns virtually instantaneously, that is a detonation.

[pmer]

It seems to me that a lot times when this happens we're working on the edges of what a cartridge is designed for. I was doing this with a 458 Lott and 45-70. I started thinking why am I trying to turn a 458 Lott into a 45-70 and why am I trying to turn a 45-70 into a 45 Colt by using reduced loads.

I got rid of the Lott and switched powders in the 45-70 to medium speed extruded like IMR 3031 and got rid of the snappy recoil from 2400 and #7. And when I think I want "reduced" big bore performance I use Blue Dot in a 44 Mag. carbine.

I never looked back.

[Finster101]

You are absolutely correct sir.

Going back thru my records…. this was July 2021

I had several rounds loaded with 6.7gr H110 (looking back that was kind of stupid but at the time i didn’t know all this) and 225 gr Berry’s Spirepoint .308 in a 300AAC cartridge with small rifle (not magnum) primer

6 rounds fired over chrono (~800-850 fps)
afterwards I did observe some strange scratches on the hulls (debris in chamber?)
none cycled the rifle (DPMS rifle with 16” barrel)

round #7 was the problem
- i felt a sharp recoil
- BCG did not cycle into the buffer
- smoke/soot coming out of every place it could find, even found soot shoved down into the magazine
- myself and several others tried in vain to pull the bolt back but could not extract the spent case
- we did record a reading on the chrono for the boolit in the 700 range (was lower than expected)
- gunsmith had to remove barrel to get the case out, found bolt face was disintegrated and had to replace that
- i still have not attempted to fire this weapon again as i think the chamber is damaged and i want another gunsmith to look at it

bottom line: i’ve learned a value lesson that i’ll never forget. i’m lucky i didn’t end up seriously injured. and much better/cheaper to ruin my rifle and buy new one than to end up in the hospital

thank you for sharing your opinion from the technical viewpoint. it very much lines up with my experience

There’s a saying we have, “sometimes you see something so stupid you know a Marine has to be involved…” I’ll take the hit on this one! (well, i already have)

That load is way under Hogdon's starting load. I have loaded and shot many subs using the published data.