H110 is weird

I tried Hodgdon H110 for 500 S&W for the first time a few weeks ago. I started with a load slightly above minimum in the Hornady book. I got flattened primers. Worse than I have had on any other load. Made me a little nervous so I went to the minimum load. Primers were severely flattened with a little cratering around the firing pin. Also some black around the mouth of the case. Fired cases just dropped right out. That did not make any sense. Primers get flatter with lighter loads. Makes even less sense with black around the case mouth. So I loaded up a batch at maximum load. Everything goes perfect. Edge of the used primers were just as round as the new ones. No signs of high pressure at all. Same primers both times. So how can increasing the load stop flattening the primers?

H110 is one of the powders that will increase in pressure if the load is too light. Didn't make any sense to me either but someone explained it to me here a few years ago. They even have a warning about it regarding the 296 which is pretty much the same thing as H110. They say that reducing loads can lead to dangerous pressure increases.

+1 on what he said

Sent from my ME301T using Tapatalk

Sounds like cartridge set-back. The pressure with your light loads isn't great enough to cause the brass to expand and seal the chamber. The fired case "sets back" against the recoil shield and flattens the primer, which is pretty soft to begin with. This also explains the "sooty" look of the light loads. Flattened primers are certainly to be considered in determining relative chamber pressure, but it isn't the most reliable indicator. If you were experiencing hard extraction of fired cases, that would be more of an indication of high pressures.

I posted a pic of the warning. Look on the right hand side in the middle and you'll see it. Like I said 296 and H110 are the same powder.

Nothing weird about H110. H110 is for near maximum or maximum loads. And ALWAYS use magnum primers. I've been using it in all my magnums & my .30 Herrett & .30-30 when I was shooting in IHMSA. I have forgot when I first used it but never have had any problems with it.

I always use Hodgdon load data for 296 and 110 as everyone else seems to start much lower than they do.

W296 and H110 are not like 2400 where you can more than slightly reduce loads...

JackM said:

Sounds like cartridge set-back. The pressure with your light loads isn't great enough to cause the brass to expand and seal the chamber. The fired case "sets back" against the recoil shield and flattens the primer, which is pretty soft to begin with. This also explains the "sooty" look of the light loads. Flattened primers are certainly to be considered in determining relative chamber pressure, but it isn't the most reliable indicator. If you were experiencing hard extraction of fired cases, that would be more of an indication of high pressures.

Click to expand...

This. Very common phenomenon with light loads, and a poor indicator of high pressure. It becomes more alarming if the primers are not only flattened but "mushroomed" to fill the whole primer hole. If it's flattened but the shoulders of the primer are still visible, that is more likely from low pressure.

I see flat primers in a lot of my magnum pistol loads but I do mostly use federal primers which are known for softer cups.

Hornady book loads can start out a little conservative. I picked a middle of the road load at 38 gr H110 under a 350 gr XTP mag for my brothers 500. When you look at Hodgdon's data however their starting load is 39 grs for the same bullet.

JackM said:

Sounds like cartridge set-back. The pressure with your light loads isn't great enough to cause the brass to expand and seal the chamber. The fired case "sets back" against the recoil shield and flattens the primer, which is pretty soft to begin with. This also explains the "sooty" look of the light loads. Flattened primers are certainly to be considered in determining relative chamber pressure, but it isn't the most reliable indicator. If you were experiencing hard extraction of fired cases, that would be more of an indication of high pressures.

Click to expand...

Pisgah said:

This. Very common phenomenon with light loads, and a poor indicator of high pressure. It becomes more alarming if the primers are not only flattened but "mushroomed" to fill the whole primer hole. If it's flattened but the shoulders of the primer are still visible, that is more likely from low pressure.

Click to expand...

We have two Bingo winners.

Sierra Rifle FAQs
FAQ - Sierra Bullets - The Bulletsmiths

Are flattened primers always an indication of high pressure?

Not necessarily. Follow along for a moment. At the cartridge's ignition, a light load won't always fully expand the case within the chamber. It does, however, develop enough pressure to force the primer out of the pocket and against the bolt face, at least as much as headspace will allow. An instant after the primer has been forced back out of the pocket, the pressure will begin to drive the case backwards towards the bolt face. As the case moves back, it reseats the primer, often flattening it in the process. When the case is extracted and examined, the primer will appear to have been used in an extremely high pressure load. In some instances, primers can be a good indication of pressure. In others, they can be extremely misleading and utterly worthless as pressure indicators.

The information above is listed under Sierra's RIFLE FAQ's. Hence the reference to the bolt face. The soot around the case mouth and easy extraction can indeed be indicators of a reduced load. However, this doesn't change the fact that the people who actually make the powder warn NOT to use too light of a load or it can cause dangerous pressures. I don't know what powder charge he's using but if there's enough of a spread between starting and max I would bump up a little from the original light charge. Not to say that absolutely it is over pressure but rather to err on the side of caution.

I've used 296 in the .357 magnum & .44 magnum cartridges, almost exclusively with cast bullets. Accuracy has been good, but 296 has an objectionable muzzle blast / flash regardless of barrel length in comparison with #2400. Accuracy with #2400 equals that of 296, though with some loads, one might give up a little velocity using #2400.

Can't really see why anyone would use 296/H110 when #2400 is available, unless the former provides better accuracy. Possible, I suppose, but I've never seen it in my guns with cast loads. Perhaps jacketed bullets are different.

Even though Hodgdon tells us not to reduce the max load by more than 3% much of the available data does. In some data the publisher stops at a charge that generates a velocity they decided was best with no rearguard for the pressure being too low.

Like said, W296/H110 performs best at the upper end of the pressure range and using a magnum primer shrinks the ES and SD numbers by a lot.

I too learned that H110 is best near the upper recommended ranges. It is my go to powder for .300 Blackout and I load it near max. Very accurate with Speer TNT bullets, generates impressive velocity with short barrels, and shoots flat. No over pressure signs in my cases at all and seems like a cleaner powder than most.

FWIW the primer always unseats from its pocket upon ignition and reseats when the case is slammed rearward from the pressure of the round.

When the firing pin hits the case it moves the round as forward as it will go in the chamber. Once the primer ignites it will unseat and move rearward against he bolt, recoil shield, or slide. Once the powder ignites and pressure is at its maximum the case will be slammed rearward with the same amount of force as is being applied to the bullet. If the pressure is too high the metal of the bolt, cylinder wall, or chamber will also slightly expand and contract. If this happens the steel grabs the brass and this causes sticky extraction. Sticky extraction is a definite sign something is amiss. A flattened primer isn't necessarily a high pressure event. Too light a load can result in primer that doesn't reseat and can bind-up the cylinder of a revolver.

Additionally, the way I read Hogdons warning implies that reducing the load causes poor ignition and possibly squids - not high pressure spikes. The warning says failure to follow the listed procedures or changing components can result in dangerous pressures. The dangerous pressure from too light a load is poor ignition and a squib.

H110 is one of the powders that will increase in pressure if the load is too light.

Click to expand...

This is patently false!

Additionally, the way I read Hogdons warning implies that reducing the load causes poor ignition and possibly squids - not high pressure spikes. The warning says failure to follow the listed procedures or changing components can result in dangerous pressures. The dangerous pressure from too light a load is poor ignition and a squib.

Click to expand...

^^^^THIS^^^^

Can't really see why anyone would use 296/H110 when #2400 is available,

Click to expand...

The reasons are that H110/W296 generally provides better velocity & accuracy at lower pressures and less PERCEIVED recoil. It also doesn't leave all those nasty hard kernels of unburnt powder all over everything including under the extractor star. Other than the previously mentioned, I can't think of any reasons either and I've been using it with both cast & jacketed bullets since 1977 when H110 was a surplus powder and W296 was newly manufactured by Olin. At that time, the two powders even smelled different.

I've used plenty of 2400 going back to when Hercules manufactured it. You can build powerful and accurate ammo with it. That said, once to get past .357 magnum ammo to .41 magnum ammo, H110 has the edge in my experience. YEMV.

Bruce

I guess it's all in how you read the warning. To me when I read that "A reduction in powder charge can cause dangerous pressures " I understand that to mean that a reduction in powder charge can cause dangerous pressures. Certainly everyone here is free to interpret that warning any way the want and my own may not be correct. But if I'm wrong, no harm...

1sailor said:

.....the 296 which is pretty much the same thing as H110.

Click to expand...

H110 & Win 296 are exactly the same powder. The only difference is packaging.


I've posted this picture before.

A while back I bought a couple 1lb. cans each of H110 & Win 296.
Not only do they have the same lot numbers, but the ink stamps even have the same blemish on the number 2 and number 4.

The top one is the 296, the bottom is the H110:

I guess it's all in how you read the warning. To me when I read that "A reduction in powder charge can cause dangerous pressures " I understand that to mean that a reduction in powder charge can cause dangerous pressures. Certainly everyone here is free to interpret that warning any way the want and my own may not be correct. But if I'm wrong, no harm...

Click to expand...

The problem is that you're interpreting the phrase "dangerous pressures" as being exclusively "high pressures". This is obviously not the case as incomplete burning produces presssures low enough to result in a squib load. In view of the fact that a squib can result is a bulged or burst barrel and those types of events are potentially very dangerous indeed; there is more than one type of "danger" to consider!

Bruce