I think the bearing surface could be a major factor.

I hadn't thought about the water, and I didn't know about the suppressor. I assume the rifle wasn't wearing a can?

Yes, he was running suppressed with a Silencerco Omega.

Guilty. I have ONE rifle, the rest are carbines. Included is a 16" 6.5CM that I wouldn't trade for anything.

Up to a point, it is called being innovative. Plow some virgin ground and you never know what it'll grow. I've safely made some cartridges do what I was told they wouldn't do, via experimentation. Of course, there are plenty of instances where you get a warning that you're getting into a danger zone. Heed the warning and stop.

Example: August 2019, 95°F I safely got a 28 Nosler to shoot a 195 gr at 3040 fps out of a 26" barrel. Why? A new powder I tried out that had zero published data for my combination. Well, go learn on the rifle range is what I do.

Wouldn't matter IMO/IME. Closer to the lands would mean increased pressure. You cannot, cannot achieve inordinarily high velocities without high pressure.

Reloading is my main hobby so I like to experiment...a lot. Back when they couldn't give Reloder 26 away because it was new and some folks deemed it sensitive to temp changes I was loading it in several cartridges with no load data and I am sure... actually in one case I KNOW over pressure with never any signs whatsoever from my rifle.
We later pressure tested loads and I was running near 70,000PSI and never had a problem except short brass life.
Right now I am running the new Staball 6.5 in a cartridge with no data to go by and getting great results and it's working good for one ammo maker so I may get to see if I overdid it again

And my sig line was actually directed at these type posts. I actually have reloading data on mimeograph paper(old timers will know what that is) that has data from Jack O'Connor dated 1954 where is is using WWII powders from 20mm that I believe was processed by Hodgdon and they sold it paper bags according to the guy who gave me the data. Point being back in the day people flew by the seat a lot. Nobody died.

The highest pressure is a peak. If you can maintain a higher average pressure for longer that doesn't have a higher peak you can achieve more velocity, from my understanding, I could very well be wrong.

My 7mm08 load is 1/2 a grain under max published data charge weight for my powder and 150 fps faster than what they say I should be getting at the max charge. Every gun, chamber, barrel, piece of brass etc is different.

You could very well have a tight chamber and be running over pressure if you’re 150 faster. Or not. Aftermarket barrel and home head-spacing can yield different pressures than factory rifles. Again, or not.

Could be, but once again, uber velocity = higher pressure, no matter what the cause is.

I get it kinda like "why do you climb that mountain"?

Speed=pressure

There are some slight exceptions with certain powders but there's no free lunch. In the case of the OP h4350 is well known and documented.

Sort of.

Not unlike "how much horsepower can I get this engine to make?" MURICA!

Part of it is that most people want a reliable load. Run at the limit of your capability and then change one thing and you can get a bolt stuck shut in your gun in the middle of a stage, or if you need to take a follow up shot on a hunt. Shoot at pressures too high for too long and you can blow the whole rifle up. Metals don't like repeatedly high pressure cycles. Fatigue failure is exponential/logarithmic, meaning that increasing the load by 10% can reduce your effective life of the gun by half or more.

I don't know what caliber your first story was referencing, but if you take a 70k load and fire it a couple thousand times in a rifle designed for 55k psi, you may be pushing up against that gun's failure point. Maybe not, but you're certainly rendering all of the engineering used to design the gun irrelevant and playing russian roulette. And folks have definitely hurt themselves badly trying to push the limits of handloading too far. You also significantly hurt your brass life and barrel life. Just makes sense to me that if you want to get more power, you would have bought a different cartridge that could handle it without being on (or past) the ragged edge of the engineering design parameters.

^^^This is it.

That's not necessarily true. You can have higher average pressure throughout the entire combustion event without having higher peak pressure. In the combustion chamber of an automotive engine that is known as brake mean effective pressure.

Yeah, well I don't know about automotive engine pressure, but I'd tell you to seat a bullet at the lands or with a slight jam, and seat the same load/bullet .050 off and see what your velocity looks like, which is a sure indication of pressure.

Not casting stones here because I have been there but proceed with caution. There are no magic loads that produce unexplained velocity well above maximum without corresponding pressure. Pressure signs on your brass is an indicator but they do not always manifest. I honestly think that tipping the powder jug used to be a lot more common before the new age, exposed turret scopes made dialing elevation commonplace. It has not been that long since sighting in for point blank range was the standard and a faster flatter load bought you more than it does today.
Hell, when I was young and crazy and thought I was bulletproof, I pushed the limits on a lot of things. I got away with MOST of it too.

I'm an engineer with a background in automotive engineering specifically directed at combustion. This is tough to get your mind wrapped around but I'll try to explain it. Gunpowder in a chamber and gasoline in a cylinder does not explode, it expands. What you're describing about a bullet being seated short or long effects something called dwell and that is very similar to how the rod length to crankshaft stroke ratio works in a Otto cycle engine. You'll notice something about the load tables for heavy vs. light bullets. Lighter bullets typically use more powder than a heavy bullet. This is because heavier bullets spend more time in the barrel then a lighter bullet does. This increase in dwell time gives the powder more time to expand and to push the bullet. Bore diameter plays a critical role in the pressure curve that is seen when you fire a gun. Everything works on a ratio. When the powder is first ignited by the primer you only have the volume of the cartridge that gas is being produced in. As the bullet travels down the bore the effective volume of the chamber gets larger and because of that the pressure starts dropping. If you are able to slow down the drop in pressure as the volume that the gas has to operate in increases you will get an increase in velocity without having the peak chamber pressure any higher. There is a staggering amount of techniques used in automotive applications to get more work out of a given volume of fuel and I'm pretty surprised that some of that combustion science has not spilled over into the gun world.

Ive read current diesel fuel injectors are capable of injecting 10 separate events per combustion stroke. Other than adding more fuel how are they achieving the extended burn/higher pressure?

Just because they're capable of injecting 10 times per combustion event doesn't mean that they're doing so in all circumstances. Diesel engines function significantly differently than a spark ignition engine. If they are actually adding fuel multiple times throughout a single combustion event I suspect they're doing so to keep the peak pressures down in an effort to prevent formation of oxides of nitrogen. Diesel engines are somewhat unique in that when the fuel is injected into the cylinder dictates how much work you're going to get out of that fuel. The entry-level performance tunes for diesel engines add the same amount of fuel but at a different point in degrees of crankshaft rotation. This change in injector timing frequently adds 70 to 90 horsepower with no other modifications but it changes the tailpipe emissions significantly.

You need to shoot more and post less and you'll likely learn something about what has been discussed in this thread. Here's another idea for you to try..........figure out what the max load is in your rifle for a specific bullet, with the bullet seated to .050 off the lands. Once the max is established, load the same exact load, but seat the bullet out to where it is jammed .010 into the lands and see what happens.

You should play nice.

There is middle ground between 50 tho jump and jammed 10. Since you know it all please give us a detailed pressure curve with peaks on all of them.

Im waiting.

Good grief man, have you considered less caffeine in the morning? I've been handloading for 34 years and I shoot nearly every weekend with rifles and every other day with handguns. I know exactly what you're talkin about and why it affects pressure. I also was not disagreeing with you. I was trying to explain why it has an effect on pressure.

[/quote]

I'm an engineer with a background in automotive engineering specifically directed at combustion. This is tough to get your mind wrapped around but I'll try to explain it. Gunpowder in a chamber and gasoline in a cylinder does not explode, it expands. What you're describing about a bullet being seated short or long effects something called dwell and that is very similar to how the rod length to crankshaft stroke ratio works in a Otto cycle engine. You'll notice something about the load tables for heavy vs. light bullets. Lighter bullets typically use more powder than a heavy bullet. This is because heavier bullets spend more time in the barrel then a lighter bullet does. This increase in dwell time gives the powder more time to expand and to push the bullet. Bore diameter plays a critical role in the pressure curve that is seen when you fire a gun. Everything works on a ratio. When the powder is first ignited by the primer you only have the volume of the cartridge that gas is being produced in. As the bullet travels down the bore the effective volume of the chamber gets larger and because of that the pressure starts dropping. If you are able to slow down the drop in pressure as the volume that the gas has to operate in increases you will get an increase in velocity without having the peak chamber pressure any higher. There is a staggering amount of techniques used in automotive applications to get more work out of a given volume of fuel and I'm pretty surprised that some of that combustion science has not spilled over into the gun world.[/quote]

Simplified, Internal combustion engines aside: same rifle, same brass, same powder, a heavier bullet creates more pressure and that is reflected in published data. Further as JGraider stated: a bullet that has a running start at the lands produces less velocity and pressure than one that is jammed, since we are dwelling on it.

That would assume that the bullet had the same bearing surface or more being a heavier/longer bullet.