working up new loads, what determines safe?

[Deavis]

I've been reloading for two years and have always followed the tables from manufacturers. Now I want to try to build up some loads of my own. I want to use the bullet of my choosing and not the manual's choice! I'm curious as to how people judge "safe" or "unsafe" with their loads since my experience there is lacking.

Obviously, without a pressure guage I have no idea what the real pressure is and thus can't *really* know if it is safe. So how does one determine what is safe? Obviously some members like Clark (no offense, your name came up in all my searches on hot load, high pressure, or heavy load), have a very different idea of safe from others. I'm not interested in going too far over the top with any loads and want to avoid that for most of my loads (practice loads).

What I have gathered from my reading is basically is to look for excessive case wear, stretching, or abnormal markings. Then look at the primer for deformation, marking, and pocket for leakage. That just doesn't seem like enough and most importantly, I see those after I fire the round!

Is there some sort of relationship for getting a relative idea of pressure from the velocity (ordered a chrono!), power factor, bullet size, or powder type? Is it, "well the manual is at 1400fps and so am I so... I guess I'm okay," or "I'll seet it a bit deeper, see how fast it goes, and watch for the primer to fall out."

I would really appreciate any advice so I can proceed safely with a little more confidence than has been inspired by reading my Lyman's manual.

 

[uglymofo]

I check for pressure just like you suggest, " excessive case wear, stretching, or abnormal markings. Then look at the primer for deformation, marking, and pocket for leakage."

I don't chrony my pistol loads anymore, and even though I do that for my rifles, I still wouldn't trust MV as an indicator of pressure. It's been my experience that some reloads are too hot for the firearm it's fired in even if it's within published norms, and MV is within expected values. I use the chrony just to give me a number so I can guesstimate ballistic performance over long distances. Dependance on a chronograph to indicate pressures could be false security if your chrony is off; also, a powder's temperature sensitivity isn't factored into a cold day's chrony data. In some parts of the country, we could be talking about at least a 70F temperature swing from winter to summer.

If I were loading for pistol competition power factors, I'd use a load that chrony'd at the minimum standard, and maybe load some that would chrony ~50fps faster, in case my (or their) chrony is off. Both these loads should be well within the powder OEM's specs, as I never saw a competition that encouraged loading max loads to achieve minimum power standards.

I've swapped out bullet shapes, using Sierra bullets (of the same general weight, say +- 2-3gr) with Hornady reloading manuals (or other OEM bullet changes vs. other OEM reloading manuals), but I start about 15% under max and work my way from there.

 

[45crittergitter]

1. Observing brass "pressure signs," particularly for a shot or two, rather than for the same load fired numerous times in the same case, is notoriously unreliable as far as staying safe. If you are getting brass or primer problems, the pressure is probably WAY too high.

2. Observe the difficulty of bolt lift and extraction.

3. Use a chronograph. If your load is faster than what the book said it should be, then your pressure is very likely higher than the book allowed, and probably too high. Helps to have numerous manuals, where more combinations of components are used. You can also get caliber specific data compiled from several manufacturers in a loadbook.

4. Most importantly, don't exceed the manual's printed data.

 

[Clark]

If you are working with a flimsy gun, like a CZ52, brass pressure signs will not be found in an incremental work up. The chamber bottom wall will have a salient response first.

If OTOH, you are working with a '98 Mauser and shooting 8mm, then there may be some advantage to reading brass.

Personally, I like to read the extractor groove with dial calipers. If it grows any measurable amount, I like to back off at least 6% to insure that I never get a stuck bolt in any hunting condition, or any combination of component variables, and my handloading consistency. This is the 1958 Vernon Speer system, and it has served me well.

Guns that I know are too flimsy for reading brass:
1) black powder antique Iver Johnson break top revolvers
2) CZ52s

Gun that are often too flimsy for reading brass:
1) 38 Specials

Guns that are tough:
1) 98 Mausers shooting rimless cartridges with .470" base


Here is a picture of three cases in a row I pulled from my '38 Turk I rebarrelled to .243

That rifle suffered no ill effects and I suffered no ill effects.
These are not the pressure signs to look for, but the picture does communicate something of the rifle's strength and gas leak routing.
The pressure signs to look for in a Mauser are sticky bolt, case head expansion, and primer top hatting, cratering, or piercing.

--
A society that teaches evolution as fact will breed a generation of atheists that will destroy the society. It is Darwinian.

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

 

[Paul "Fitz" Jones]

What is Safe

The powder and bullet companies determine what is safe from the factors mentioned here and from complaints from users of their previous recommendations that resulted in damage and injuries. The complaints probably arised from customers using the more cheaply or weaker designed weapons and all customers of currently made and advertised weapons have to be taken into consideration when publishing data with their powders or bullets.

For example when 44-40 ammo is made for rifles and pistols it has to be safe in the pistol but hotter loads could be worked up for the rifle as long as they are never used in the pistol. I have some 2,000fps loads for my .357 mag 1892 Winchesters but I paint the casings red to keep them from my revolvers.

So the manuals are a guideline for the lowest denominator and depending on your faith in the quality of your weapon and its reputation for quality then experimention in reading all the signs mentioned in this thread can be safely accomplished.

Fitz

 

[Deavis]

Thanks for the advice guys, I appreciate it. I'll get a few more manuals so I can do some cross-referencing and then get started carefully.

Question...
It seems to me, and correct me if I'm wrong, but if I use a smaller bullet than a manual uses, say in length, that if I used the same OAL I would most likely be producing lower pressures than the larger bullet load?

Also, when working with powders not specifically outlined by a manufacturer, I could probably get a good idea of where to start by finding a powder with a similiar burning rate that has been documented and working around that data area?

 

[Clark]

There can be problems with imagining a load and trying it:
1) Some cast bullets give high pressures for thier wieght.
2) Powder burn rates vary with pressure: Power Pistol may be faster than AA#5 on the burn rate chart, but at really high pressures in experimental loads, AA#5 is the much faster of the two.
3) So you imagine a load and start much lower and work up. But if that gun is weaker than the brass, like CZ52s and most revolvers, the chamber bursts before the brass shows definative pressure sign.


What does it all mean?
If the gun is not stronger than the brass, you are stuck following what the manuals say.

 

[Deavis]

I want to develop my loads for my handguns first and was going to use my HK USP on the .40 side and a Springfield XD on the 9mm side. I would hope that the barrels on those guns exceed the SAAMI specification but then again, nobody is going to say so from either of the manufacturers. Maybe I should look into custom barrels for them and go from there...

 

[Clark]

Deavis,
I have experimented with 9mms and 40sws to find the threshold of "what is NOT safe", but none of the pistols were HK or Springfield.

I sent you a private message.