Pressure signs

[Clubster]

I loaded some H110 loads using 240xtp bullets, 24.1gr and mag primers. The primer shows a little flat and pin hole is not showing a ring. It’s being shot out of a 629 Smith. Case is fine and shot fine but thoughts if this is acceptable? Would upload pic but it keeps saying failed upload.

[ligonierbill]

Do the spent cases come out easily?

[Clubster]

No issues at all coming out of the cylinder.

[jetinteriorguy]

Originally Posted by Clubster

I loaded some H110 loads using 240xtp bullets, 24.1gr and mag primers. The primer shows a little flat and pin hole is not showing a ring. It’s being shot out of a 629 Smith. Case is fine and shot fine but thoughts if this is acceptable? Would upload pic but it keeps saying failed upload.

I’m assuming when you say pin hole you mean the indentation from the firing pin and not an actual hole, so you should be fine. But if you are actually getting a hole in the primer from the firing pin you have a big problem.

[Unclenick]

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.


24.1 grains should be no issue. Winchester used to publish a flat load (no starting load) of 24 grains under a 240-grain JSWC and said to use no more and no less. Their powder was labeled 296, but H110 is the same St. Marks Western Cannon WC296 in canister grade. A 0.1-grain overload is within the tolerance expected of a powder measure set to throw 24.0 grains.

[Shadow9mm]

Looking at Hornady data it shows a max of 24.8g, and your cases are ejecting smoothly, Id say you in good shape. Good pressure but not over pressure with plenty of wiggle room.

[Jim Watson]

When I was shooting IHMSA a long time ago, a 240 Hornady and 24 gr of H110 was THE .44 magnum load.
I was cheap and shot cast and 4227. (2400 was faster, 4227 was more accurate.)

[Clubster]

Yes, indention from firing pin. No holes.

[Clubster]

Thanks for the info and will keep making more

[44 AMP]

24gr of H110 and a 240gr bullet will put you into the 1400fps range, with enough barrel.

IF the primers are not cratered, not pierced, not flattened enough to have flowed to the edge of the pocket AND the cases extract normally, you have pressure, but NOT EXCESSIVE pressure.

The most important thing is not what the primers look like but whether or not cases extract normally, or stick in the chambers. If the cases stick, the pressure is too high for your gun and load combination. Doesn't matter what the primer looks like, or what the books say should be ok, if the cases stick in your gun, your load is too hot for your gun.

[TX Nimrod]

Primers can be a very poor method of estimating pressures. Speer covers this in detail in their Manuals, see the figure below. Since the OP is not experiencing other signs of excess pressure, his load is likely safe. BTW, just because his load is in the books doesn’t mean his pressures are not excessive. That’s why the manuals say NOT to start with the max load, and why different manuals show different max loads.

[IMG][/IMG]

https://ibb.co/wJTGPMT

[Clubster]

Interesting info and thanks!

[Unclenick]

The problem is that different primer brands have variations in cup thickness and hardness, so they can't respond to the same pressure in the same way. Additionally, different guns have different chamber head clearances, so primers go off with different amounts of room to back themselves out of their pockets (which they do if they are not staked like military loads) after the firing pin strike has pushed the cartridge forward. Building pressure and the start of bullet movement then pushes the case back, reseating the fired primer. When the head clearance is large, the sides of the primer near its bottom can expand more before the case backs up than they would with a small head clearance, making it easier to get a flat appearance or even mushrooming of the head.

The bottom line is that between primer and gun variations, the only thing flattening and mushrooming primers can tell you for sure is that you are approaching a pressure limit for that particular primer in that particular gun, and it may be on the edge of piercing. A different primer may have a worse problem or no problem with the same load, and there is only one way to find out, and that is by switching primers. You can surmise that the primer is in conditions beyond what its maker expected it to see. If it's a magnum primer, I would be wondering about the absolute pressures. If it is a thin, light primer like a Remington 6½ in a high-pressure round, I would expect it to show signs of trouble before the round reaches its rated pressure. In other circumstances, you may reach excessive pressures without the primer, looking troubled in the least. A +P 38 Special load, for example, could go well beyond SAAMI's rated pressure without a primer showing any distress.

There are just too many variables for primers to tell you anything about absolute pressure reliably.

[44 AMP]

Primer pressure signs are reliable indicators that you have enough pressure to create those signs. They are not measuring devices, they are not calibrated, they do not tell you how much pressure there is, or whether or not it is above or below any standard. They just show you something is there, that isn't there when you don't get the signs. What, and how much, you have to figure out from other things.

Kind of like the "idiot lights" on your car's dashboard. They light up when their sensors tell them something is out of range, but not what, or how much.