Proper COL / Seating Depth for Berrys HBFN

[ThatsNice]

Welcome to the forum. Please go here to introduce yourself.

The answer to your question is NO! There are many powder numbers available because the characteristics of each one is different from the characteristics of the others, and one of the things that difference means is they do not produce the same velocity from the same peak pressure. When velocity matches, it means the average pressure in the bore was a match, not the peak pressure. In general, slower powder produces the same average with a lower peak pressure value and a higher muzzle pressure value. Fast powder producing the same velocity will have a higher peak pressure and a lower muzzle pressure to get the same average pressure. However, excessive peak pressure is what can damage the gun, so loading for velocity with a powder that has a faster relative burn rate in your chambering and with your bullet choice than the powder the commercial manufacturer used will raise the peak pressure above what his load got.

A fast powder is used instead of a slow powder when a lower velocity load, like a target shooting load, is desired. It is used instead of slow powder because the slow powder loaded to lower velocity and pressure doesn't burn very well, which means it wastes powder and produces a lot of fouling to clean up. Slow powders don't like reduced pressures.

Look for powders with published load data that produce the velocity you want, and obtain one of those powders.

THANK YOU!

 

[ThatsNice]

Thank you!

 

[ThatsNice]

No, do not increase beyond published loads to get to a published velocity. That is flawed, and potentially unsafe, thinking. A shorter barrel will generally achieve lower velocity. There is no such guarantee that you can reach a published velocity out of a shorter barrel.
I suggest that you selected your load for the highest theoretical velocity, considering the barrel length. What you get from that load is what you will get from your pistol.

Thank you as well!

 

[44 AMP]

I skimmed this thread, and one of the things I noticed that didn't get touched on back when the main discussion was going on was "how much of the bullet is in the case"??

Lots of discussion about COAL, what's too long, too short, how different COALs change pressure, etc. None of it looked at the seating depth of the bullet base. And that is what controls available powder space and thereby affects the pressure.

A longer pointed bullet and a short stubby one can have identical seating depth in the case, but very different overall loaded lengths.

The way I see it, for something like a 9mm Luger round overall length matters to keep the bullet off the rifling and let it fit and feed from the magazine. Any length that does that, and keeps the proper amount of bullet inside the case, keeping the powder space correct for the powder charge works just fine. But if meeting an arbitrary over all loaded length changes the powder space volume, you can have issues....

Welcome to TFL and listen to Uncle Nick, his advice is sound and valid.

 

[jetinteriorguy]

I use this method for determining seating depth in semi auto pistols. Start with making a dummy round seating the bullet as long as your mag can handle reliably. Then pull the barrel and start plunking it. Keep seating deeper until it plunks, then seat it .010 deeper to allow for bullet variances. Then make four more and hand cycle them through to make sure they work in your gun. Then work a load up starting from the bottom being careful not to get a compressed load before hitting the maximum recommended load. Then test for accuracy, and after finding the load you like load twenty more and test again. If all this works out then load away. One other step for me is to do this with whichever of my pistols is the most finicky, such as a short throat or any feeding issues particular to that gun.

 

[44 AMP]

Then pull the barrel and start plunking it.

I don't disagree with your methods, only wish to point out that "pulling the barrel" isn't possible with every single semi auto out there.

 

[Unclenick]

But also note that while the plunk test works well with jacketed bullets unless the case becomes too short (firing shortens 45 Auto cases rather than stretching them like rifle cases), with softer bullets like cast or plated, you usually get the best accuracy by jamming the throat with them if the magazine can still accommodate them that long and they still feed at that length. For guns that the barrel comes out of easily for use as a gauge, getting the head flush with the back end will usually feed. This uses the bullet for headspacing rather than the case mouth. I've had this practice cut group size by as much as 40% as compared to plunking soft bullets.