Increase velocity of H110 in a 357 rifle using standard primers?

[shinyroks]

Quick question if anybody has experimented specifically with a rifle using standard primers behind H110 to run a slower burn rate for the longer barrel.

I have experienced (and read) unburned H110 powder out of a Smith 66 4" using standard primers, and was wondering if a full 24" barrel (Puma 92) without the flash gap might leave time for the powder to burn more slowly, or if that is a dead horse and the powder would still not ignite properly...

Not looking for ridiculous power or anything, just thinking projects...

Current load is 15.9 under a 158 Nosler HP (Nosler data) and WSPM primer.

 

[Macchina]

That's not really how gunpowder works and especially not a pressure sensitive powder like H110.
I'm not an expert at internal ballistics but get some of the basics:

When burned in open air you'll notice that black powder flashes very quickly and smokeless powder burns very slowly (a few seconds to burn a pile of rifle powder).
When contained black powder burns at the same rate (regardless of response pressure) and smokeless powder burns faster as pressure builds.

The goal for any powder is to burn (which creates gas which creates pressure) at an increasing rate as the bullet travels down the barrel. Coated grains, different shapes, etc all come together to control the burn rate of powder to get the pressure curve just right for the intended cartridge and barrel length. Note that the volume of space in the barrel behind the bullet gets larger as the bullet travels down the barrel. The bullet is also accelerating. The gas generated from the burning powder must increase in volume to not only account for this volume increase behind the bullet but also at an increasing rate to counter the increasing velocity of the bullet and still build pressure behind it. A perfect powder would maintain a constant pressure (45k psi or so) behind the bullet the entire length of the bullet. This doesn't happen and is near impossible but would create a very fast bullet and VERY loud muzzle blast.

Powder does not burn instantaneously, this would cause a pressure spike of millions of pounds of pressure and explode a gun. The burn rate of powder is the short period of time the powder CONTINUES to burn after ignition. A perfect primer would ignite every grain of powder evenly and instantly so they could all complete their burn event starting at the same time.

Any powder not ignited in the initial event can actually not ignite at all. Going back to the beginning of my post: as pressure decreases the smokeless power is less likely to ever ignite. This is why you get unburnt H110 with a standard primer or with an uncrimped case that never correctly came to peak pressure.

Any unburnt H110 in a barrel isn’t going to spontaneously ignite with the bullet ¾ of the way out of the barrel. Even if it did, the best you could hope for is complete ignition of all the powder: and then you just have the exact same amount of gas that would have been created initially if you had a good clean burn of all of your powder at the ignition event.

 

[shinyroks]

That's not really how gunpowder works and especially not a pressure sensitive powder like H110.
I'm not an expert at internal ballistics but get some of the basics:

When burned in open air you'll notice that black powder flashes very quickly and smokeless powder burns very slowly (a few seconds to burn a pile of rifle powder).
When contained black powder burns at the same rate (regardless of response pressure) and smokeless powder burns faster as pressure builds.

The goal for any powder is to burn (which creates gas which creates pressure) at an increasing rate as the bullet travels down the barrel. Coated grains, different shapes, etc all come together to control the burn rate of powder to get the pressure curve just right for the intended cartridge and barrel length. Note that the volume of space in the barrel behind the bullet gets larger as the bullet travels down the barrel. The barrel is also accelerating. The gas generated from the burning powder must increase in volume to not only account for this volume increase behind the bullet but also at an increasing rate to counter the increasing velocity of the bullet and still build pressure behind it. A perfect powder would maintain a constant pressure (45k psi or so) behind the bullet the entire length of the bullet. This doesn't happen and is near impossible but would create a very fast bullet and VERY loud muzzle blast.

Powder does not burn instantaneously, this would cause a pressure spike of millions of pounds of pressure and explode a gun. The burn rate of powder is the short period of time the powder CONTINUES to burn after ignition. A perfect primer would ignite every grain of powder evenly and instantly so they could all complete their burn event starting at the same time.

Any powder not ignited in the initial event can actually not ignite at all. Going back to the beginning of my post: as pressure decreases the smokeless power is less likely to ever ignite. This is why you get unburnt H110 with a standard primer or with an uncrimped case that never correctly came to peak pressure.

Any unburnt H110 in a barrel isn’t going to spontaneously ignite with the bullet ¾ of the way out of the barrel. Even if it did, the best you could hope for is complete ignition of all the powder: and then you just have the exact same amount of gas that would have been created initially if you had a good clean burn of all of your powder at the ignition event.

I was pretty sure that was going to be the answer. Thanks for the explanation of the burning process, that helps a lot.

 

[Whiterook808]

I am pretty sure you will get more reliable ignition using magnum primers with H110.

 

[slickracer]

H110 should have magnum primers, period.

 

[CraigC]

Yep, the primer affects what happens inside the case, not down the barrel. Magnum only.

 

[buck460XVR]

I am pretty sure you will get more reliable ignition using magnum primers with H110.

Kinda the reason most load manuals tell us to use 'em with H110/W296. Especially with .357. With larger capacity cases that work with higher chamber pressure, they are not as critical.

What makes H110/W296 a magnum powder is it's slow burn rate. To get this slow burn rate they coat the powder with deterrents to slow it's burn. Thus it can be hard to ignite under certain conditions. Low case fill, little or no crimp and extreme cold temperatures. If one always used a max or near max load and a heavy crimp, magnum primers would not be needed. But, add together a less than minimum load, a loose crimp and cold temps, odds are you will get a fizzle instead of a bang without the use of magnum primers.

 

[Blue68f100]

I don't know if this has been mentioned but normally with W296/H110 you only reduce the charge by 3% from max listed. This powder requires a heavy crimp for it ignite the powder efficiently. Get too low on charge and light crimp you will get erratic velocity and unburned powder. The reason this powder is best for full tilt Mag loads. It's also a good powder for the 458 SOCOM.

 

[Whiterook808]

It is also the only powder I use for .30 Carbine.

 

[murf]

.004" neck tension is much more important than most anything else with that h110/357 magnum combo. you need to hold the bullet back as long as possible to burn that slow powder well. a magnum primer is also a must with that combo.

luck,

murf

 

[Rule3]

I don't know if this has been mentioned but normally with W296/H110 you only reduce the charge by 3% from max listed. This powder requires a heavy crimp for it ignite the powder efficiently. Get too low on charge and light crimp you will get erratic velocity and unburned powder. The reason this powder is best for full tilt Mag loads. It's also a good powder for the 458 SOCOM.

That is what "they" and the internet have been saying for years, but looking even at Hodgdon data the reduction from Max to Min is MORE than 3%. Most any manual data show more than a 3% reduction. it is more like the old 10%
I am not saying it should be reduced much if any. Pretty much all or nothing powder. But there is no logic to their"3% rule"
357 mag, 158 gr A significant increase in pressure for just 1.7 grains!

15.0
1,418

28,600 CUP

16.7

1,591

40,700 CUP

http://www.hodgdonreloading.com/data/pistol

 

[Blue68f100]

When I 1st started using it back in the 70's they (win) had a note "DO NOT REDUCE". Then a couple of years later they said it could be done by 3%. But all this was for Handgun's. It was not used in any rifle loads except the 30 carbine. Which was treated as a pistol load.