please share your (bad) experience using underpowered loads

[PrestoColumbus]

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

A few months ago I think I may have ruined my bolt with an underpowered load (225gr 300AAC with H110 powder in an AR platform). I think I had what’s called a “flash over/detonation” because the H110 is position sensitive and I didn’t have enough powder in it. I’m still trying to understand it

I’m trying to understand the risk/danger with underpowered loads.

I think I understand why overpowered loads are dangers (too much pressure and no where for it to go…) but I would think the only danger from underpowered loads is just the risk of having a squib

Are there some experiences that can be shared to illustrate what can happen?

I thank you in advance for sharing, I very much want to learn from others so I don’t repeat those mistakes and then I will be free to make all new ones

[BJK]

I have never experienced it but I've heard it referenced as "detonation". I've never used WW296 below the suggested load data.

The only negatives I've experienced are butterfly fart loads in 9mm using other powders. They tested fine but in competition they gave random malfunctions. Annoying but not dangerous or anything that would damage the firearm.

But H110 and WW296 are noted for not being tolerant of low charges. But used as they are supposed to be used they are good powders (they are the same).

[Hick]

fundamentally, slower burning powders need to be loaded in such a way that the flame cannot reach all the powder at once-- like a rocket engine that burns from the base to the nose. If you go too low the powder can spread out in the case and expose too much to the flame of the primer-- bad news. So, if you want to go low you have to go so low that all the powder burning at once will be ok, like a firecracker. This is why low velocity loads often use small amounts of fast burning powder. The danger region is in-between those two. H110 is not a fast powder-- so underloading can be a problem.

[Petander]

I have a weak primer -story:

My friend,a shooting instructor,was test shooting a new factory load from a certain factory. Bad 100 m groups, sooty brass. Sort of weak ammo.

I was shooting a similar Tikka T3 Tactical 300 WM, he gave me some rounds to see how it goes with a suppressor, I had one mounted. After three mild feeling shots, bad accuracy and sooty brass I got a clear "CLICK-BANG!".

Could not open the bolt with any reasonale tool. My friend took my rifle to Sako, they had to remove the barrel to get the bolt and brass out.

Diagnosis: A bad batch of primers. A weak primer can start burning the powder a little, while moving the bullet, then you will have much more space for the powder to burn plus an obstruction-like situation. And all of a sudden it burns at once. Insane pressure.

Underpowered primers can be dangerous. This T3 Tacticsl is the only rifle that Sako has not managed to blow up with pistol powder bomb-charges.

[Gator 45/70]

To low of a charge and you're going to keyhole, Never keyhole!!!

If you're running a can then so much the worse damage you will get !

[JimB..]

There are stories of detonations from low powder charges, but to my knowledge they are not repeatable. I believe that most, if not all, are accidental dbl charges.

[Harter66]

I abandoned H110 for 45 Colts Ruger for these reasons ;
Mag primers , one more thing to stock .
Heavy crimps , that brass gets enough abuse without that .
Minor changes in OAL caused everything from throat jams with gas hiss to 250 fps rises in velocity . Like .05 gross length changes .

I use Unique to get my desired velocity with a standard LRP that is shared with several other cartridges .

Steel dies fixed a lot of the brass abuse but with brass being $35/100 and up I like to save it as long as I can .

At least if I do get a little pull or set back with Unique I don't have to worry about a blooper stuck or barely clearing and the next one going 1400 fps they all go 1000-1050 in the pistol and 1200-1260 in the carbine .

I tried really hard to like H110 ........

[PrestoColumbus]

To low of a charge and you're going to keyhole, Never keyhole!!!

If you're running a can then so much the worse damage you will get !

what is a keyhole?

[memtb]

A few years ago (about 1971 or 2), I was 18ish, and had just bought some yardsale (estate) reloading equipment. One of the items was an Ideal#55 powder dispenser. Never having used anything except the little dippers with a Lee Loader, no training from an adult, and no internet to learn from.....I thought that I had my #55 set-up properly. I was attempting to drop 2.8 grains Bullseye under my homegrown cast 148 WC’s. Yes, a 10 cavity Hensley & Gibbs 148 grain, flat-base WC mold was part of my estate sale purchase! I adjusted the #55, once getting a proper charge....never checking to be certain that it was throwing consistent charges.....it was not!

I loaded up a bunch, very excited about the speed at which I could now reload cartridges. I went to my local shooting spot, and proceeded to send bullets downrange....rapid-fire! Fairly early on, I got a very weak discharge, but being in the rapid fire mode....I touched-off another round! The recoil from that shoot was quite pronounced! I immediately knew something was not right, neither I nor the handgun were “worse for wear”! Thankfully, it was a Model 28 S&W, or the results may have been different. Apparently, I had a “squib” load.....followed-up by a good round! Knowing that something was right with the powder charge, I went home and experimented with the #55. As memory serves me, I didn’t realize/understand that there were 3 different sizes of charge bars and I was using only the largest....resulting in very inconsistent throws!

A lot was learned on that first outing with my new very used) equipment! memtb

[Mal Paso]

There are stories of detonations from low powder charges, but to my knowledge they are not repeatable. I believe that most, if not all, are accidental dbl charges.

Except in many cases there is just enough room for a single charge. In 44 Mag I could fit only 2 or 3 more grains more than max charge. I have never had anything but inconsistent combustion from light 296 loads but I can’t say for sure the SEE events are false.

[Mal Paso]

what is a keyhole?

Boolit doesn’t stabilize and tumbles going through the target sideways.

[Baltimoreed]

A keyhole is when your bullet strikes the target sideways instead of nose first so it leaves a hole in the target the shape of the profile of the bullet. Usually caused by bad rifling, leading, undersized bullet, too fast, too slow etc where the bullet is not getting stabilized so it tumbles instead.

[rockrat]

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!!

[almar]

I abandoned H110 for 45 Colts Ruger for these reasons ;
Mag primers , one more thing to stock .
Heavy crimps , that brass gets enough abuse without that .
Minor changes in OAL caused everything from throat jams with gas hiss to 250 fps rises in velocity . Like .05 gross length changes .

I use Unique to get my desired velocity with a standard LRP that is shared with several other cartridges .

Steel dies fixed a lot of the brass abuse but with brass being $35/100 and up I like to save it as long as I can .

At least if I do get a little pull or set back with Unique I don't have to worry about a blooper stuck or barely clearing and the next one going 1400 fps they all go 1000-1050 in the pistol and 1200-1260 in the carbine .

I tried really hard to like H110 ........

I had a harsh learning experience with that powder as well. Improper crimps and standard primers in a 500 mag, the ignition was so poor that It pushed the bullet into the forcing cone and jammed the cylinder. It was a mess. That powder works well but it needs special care. I would say the same about lil gun. I use h110 in 300 AAC but I'm careful about it now. Its not my favorite powder I can say that much for certain.

[414gates]

Too little fast burning ball powder in a large case causes SEE, secondary explosive effect.

I had it in my 40S&W loads once that my son was shooting at the time, thankfully without a scratch to him.

Don't go below the minimum in the book. Some of the more recent load guides now mention the danger of an undercharge, none of the old books do.

If you need a reduced load in a pistol, use a flake powder, not ball.

For rifle, fill the empty space with dacron. I'm personally allergic to air in my rifle cases, but each to their comfort zone.

[Mal Paso]

AA2 is a ball powder with none of 296s problems. Ball/Sphere is just the process. Started as a way to make WW1 cannon powder usable in small arms. It is a less expensive, more flexible process.

[Polymath]

When I started reloading for 300 Win Mag, I started low on the powder charge. Got 8 hang fires and a couple of duds out the first box. Pulled the bullets on the duds and the powder was stuck, laying flat in the case. Solid and white. Looked like sugar. I scraped some out.
I increased the charge a few grains and used mag primers for the lower charges. That problem went away. Once I found my preferred load, I went with that.
Now, I do not always start with the least powder charge. I used to do that with some Dominion Powders (as per directions)
If it's a new or different powder you have never used before that is a good idea, however after you shoot some for a while you kind of get to know what it's doing.

[JSnover]

I've had three squibs and was able to pop them out easy enough. Luckily I stopped and investigated before anything else went wrong.
I try to keep my 'light' loads above 50% case capacity but when I load really light I double check everything before I seat the bullets.

[JimB..]

Except in many cases there is just enough room for a single charge. In 44 Mag I could fit only 2 or 3 more grains more than max charge. I have never had anything but inconsistent combustion from light 296 loads but I can’t say for sure the SEE events are false.

It is extremely difficult to prove a negative, so I also can’t say that the effect doesn’t exist, only that as far as I know nobody has ever been able to intentionally make it happen.

Rockrat believes that he had one with AA#9, but it was only one of 9 cartridges that he sincerely believes were as close to identical as he could make them. Wonder what the variable was. Could he have had a squib when he thought he missed the target on the second shot? Could he have double charged? Could a bullet have gotten set way back somehow? Could the powder have settled differently in the case that one time? That he went from shooting well to not shooting well makes me think there was something going on rather than just suddenly one bad cartridge. Wonder if the timing got way off somehow and he was spitting lead all over the place. Really hard to tell once the gun comes apart. Not saying that he’s wrong, just that there is no way to prove that it was caused by a light load.

[.429&H110]

FWIW
H110 is great powder for 44 mag in a superredhawk.
240gr keith boolit with mule snot, 1200fps is the ticket, accurate at 100 yards
I don't know why there is very little leading.
I have loaded 4721 44 mag with dozens of different loads
sometimes coating the bore with lead, testing at -40 to 115F
320gr bear loads to 180 gr "high speed" I have only shot one chronograph so far...
Certainly changing crimp changes everything else!

YMMV 20gr H110, no magnum primer, 240 grain keith boolit
will leave unburned powder in the brass. Goes plonk not bang.
IF that powder were to burn later, it would be bad.

H110 needs pressure to burn completely and -10% is not happening here.

Search this site for the difference between magnum primers and normal primers, would take all day to read it all.
18 yo kid showed me how to set up a bench, then showed me this forum.
Thank you!