Velocity vs pressure. Am I gonna kill myself?

[gunpa]

I've previously posted about how anemic A.P.P. powder is, well I did some more tests today using my just received No Excuses 485 grain Conicals. My intention was to use T7. I started with 90 grains behind these tiny bullets. First shot hangfire. Second third and fourth were the same. This is a just opened can of powder. Works fine with roundball.
Anyway, I got mad and decided to see how much APP it would take to match the velocity of T7 at 1350 fps. 130 grains is the answer. Needless to say, the recoil was borderline horrendous! I'm matching T7 but wondering how velocity equates to pressure. I realize the larger powder charge is part of the ejecta which also adds recoil. 50 yard group while adjusting sights. Shot above center was final adjustment. No more hangfires!

 

[64Springer]

As a general rule, higher chamber pressure equates to higher velocity.

More powder. More pressure. More speed.

130 grains sounds way unnecessary.

Unless your goal is to achieve/exceed .45-70 Government ballistics.

 

[#blackpowderbill]

I've shot plenty of app powder. Even before they had to change their name

I was only shooting round ball & my point of impact didn't change.

 

[chorizo]

Are you chronographing the loads to match the velocity or just going on bullet placement? Bullet placement doesn't necessarily exactly correlate to velocity

Complicated question....there is a correlation between pressure (the force that builds to make the bullet gain speed) and Velocity.

Here comes the rub: When is the pressure peak, how sharp is the pressure peak (is it quick or drawn out) and how much is the pressure peak, how long is your barrel and does it allow for complete burn of the powder.

Faster burning powder peaks velocity more rapidly causing a sharper peak. A heavier bullet causes a higher pressure peak as it doesn't accelerate as fast. Slower burning powder typically spreads the peak out as does a lighter bullet and means that the pressure doesn't peak as high.

Warmer powder temps causes higher pressure as the powder will burn more readily than cold powder.

So the answer is complex and you don't really know unless you can have it pressure tested with the particular bullet, powder, and temperature.

the link below will give you some guidelines. I have found (via chronographing well over 50 different loads in 58 cal and 54 cal) T7 velocity numbers are 10% higher than what the calculator shows and by adding 10% it is pretty close to what the calculator says...1% or less difference.

https://www.p-max.uk/cgi-bin/black_powder.cgi

 

[gunpa]

I'm chronographing each shot. Average velocity of T7 was 1360 so I loaded app till I averaged 1330. But T7 hangfires no matter what I do. 90 grs T7 vs 130 of app. Big difference in recoil!

 

[NorthFork]

Why? Why abuse yourself in this manner? Buy some darn black! It's everywhere begging to be bought. No need for the T7 or APP or Pyrodex.

 

[chorizo]

T7 is much cleaner and easier to clean. Additionally Black Powder cannot be had where I live....that's why. Shoot what you want, I shoot what I want.

I use musket caps and do not have hangfires.

 

[64Springer]

I'm chronographing each shot. Average velocity of T7 was 1360 so I loaded app till I averaged 1330. But T7 hangfires no matter what I do. 90 grs T7 vs 130 of app. Big difference in recoil!

I'm wondering if your hang fire is simply 130 grains of T7 powder trying to burn along that long column of powder.

I can't find the caliber you're shooting.

The smaller the caliber, the longer the powder column.

 

[ETipp]

T7 is much cleaner and easier to clean. Additionally Black Powder cannot be had where I live....that's why. Shoot what you want, I shoot what I want.

I use musket caps and do not have hangfires.

Yes, hotter spark. That's why they made those enclosed nipple, hot spark ignition that uses 209 primers.

 

[smoothshooter]

I've previously posted about how anemic A.P.P. powder is, well I did some more tests today using my just received No Excuses 485 grain Conicals. My intention was to use T7. I started with 90 grains behind these tiny bullets. First shot hangfire. Second third and fourth were the same. This is a just opened can of powder. Works fine with roundball.
Anyway, I got mad and decided to see how much APP it would take to match the velocity of T7 at 1350 fps. 130 grains is the answer. Needless to say, the recoil was borderline horrendous! I'm matching T7 but wondering how velocity equates to pressure. I realize the larger powder charge is part of the ejecta which also adds recoil. 50 yard group while adjusting sights. Shot above center was final adjustment. No more hangfires!

Why not use real black powder? It ignites easily and the burning characteristics are more predictable.

 

[chorizo]

Why not use real black powder? It ignites easily and the burning characteristics are more predictable.

Well, in SW Idaho you can't readily find black powder for one. The storage requirements in Ada county are prohibitive for the retailers. All you can find are the subs.

I not sure where Gunpa lives in Idaho, but I suspect he is right here in the same boat as I am.

 

[Steve Wagner]

Are you chronographing the loads to match the velocity or just going on bullet placement? Bullet placement doesn't necessarily exactly correlate to velocity

Complicated question....there is a correlation between pressure (the force that builds to make the bullet gain speed) and Velocity.

Here comes the rub: When is the pressure peak, how sharp is the pressure peak (is it quick or drawn out) and how much is the pressure peak, how long is your barrel and does it allow for complete burn of the powder.

Faster burning powder peaks velocity more rapidly causing a sharper peak. A heavier bullet causes a higher pressure peak as it doesn't accelerate as fast. Slower burning powder typically spreads the peak out as does a lighter bullet and means that the pressure doesn't peak as high.

Warmer powder temps causes higher pressure as the powder will burn more readily than cold powder.

So the answer is complex and you don't really know unless you can have it pressure tested with the particular bullet, powder, and temperature.

the link below will give you some guidelines. I have found (via chronographing well over 50 different loads in 58 cal and 54 cal) T7 velocity numbers are 10% higher than what the calculator shows and by adding 10% it is pretty close to what the calculator says...1% or less difference.

https://www.p-max.uk/cgi-bin/black_powder.cgi

Well said chorizo, especially the part about bullet placement. I haven't done the testing with ML's and the chrony yet, but after thousands of rounds from unmentionable rifles put through my chrony I have noticed that, very frequently, higher velocity rounds from same gun, with same bullet, will show up lower on the target at closer ranges. 100-300 yards w unmentionables. Fouling shots with a clean barrel will be slower with the same load and show up high and left or right. Not always, but more often than not. Lots of harmonics and other variables, like the pressure curves you mention, involved so one should not automatically expect higher velocities to show up higher on a target. Not sure how this pans out with ML's but it seems the principles involved would be the same. BTW, one does not need to have a chrony to figure velocity if the ballistic coefficient of the bullet is known. Shoot a same load group at 50 yards and then do it at 100, both times aiming at the same bull without any sight adjustment. Measure the drop from center to center of each group and go to the charts. It doesn't matter where your groups land in relation to the bull, just measure the drop. I do tons of load development without any sight adjustment as long as I am on paper. I just look for the load that makes the best groups and go with it. [unless I find the velocity unacceptable] Then, I adjust accordingly. SW

 

[necchi]

Well, Ice will help,, those frozen gel packs work. Just wrap it in a towel,,

 

[Tumbledown]

T7 is much cleaner and easier to clean.

Cleaning BP is about as easy as it gets.

Additionally Black Powder cannot be had where I live....that's why.

Mail order is your friend. I bought 4 lbs from Graf's, with shipping it was less than 3 lbs of 777 locally.

 

[French Colonial]

Cleaning BP is about as easy as it gets.

Mail order is your friend. I bought 4 lbs from Graf's, with shipping it was less than 3 lbs of 777 locally.

BP can be shipped by numerous distributors, I have used Graf's and Powder Inc. in the past to buy case quantities and to the best of my recollection have not bought powder locally in 20 years or so.

If you plan on sticking to this hobby of ours, order a few years worth of real BP and spread out the Hazmat and quit fooling around with the fake BP, you will be happier with ignition and every other aspect I would imagine.

 

[chorizo]

Been doing ml for about 55 years of my 68 years.. I guess I would call it sticking to it. I will say again, shoot what you want, I will shoot what I want. But, hey, thanks for the fan boy diatribes . T7 works for me.. Thank you very much.

 

[rich pierce]

Expect high recoil with what you are trying to achieve. Essentially it’s like a high velocity waterfowl load in a shotgun (velocity and weight).

 

[French Colonial]

Been doing ml for about 55 years of my 68 years.. I guess I would call it sticking to it. I will say again, shoot what you want, I will shoot what I want. But, hey, thanks for the fan boy diatribes . T7 works for me.. Thank you very much.

And that is great, bless your heart you get to shoot whatever you want.

My point being to the newbies that if you want to shoot real BP it is available from many sources.

 

[45man]

My Hawken .54 shoots best with Pyrodex and I have worked loads until blue in the face and shoulder with other powders.
T7 is OK but it hates ANY compression at all. All you want to do is touch it with the ball or slug. If you lean on that ramrod you will have all kinds of funny results.

 

[Johnny Tremain]

More powder. More pressure. More speed.

But there is a threshold.

Your barrel can only burn some much powder (Davenport Formula).
Any that is unburnt does not help in speed, its just a waste.

As far as harming your barrel. Get a copy of a Dixie Gun Works catalog
(everyone should have one)
In the back they filled a modern barrel with powder, doubled balled it, and remotely fired it.
Barrel took it all, no damage.