Determining max. loads

[gravelyctry]

I'm fairly new to reloading, and have read a couple of hte books on it and the Nosler and Hornady reloading manual information. Everywhere I see, it says to use the max. published loads with caution, starting out lower and working your way up. It sounds like somehow the max. load is based on the firearm.
My question is this: how do you determine what the max. load is for a firearm? There's no way (best I can tell) of measuring pressures. I can look at the cartridges to see if there's any of the signs of overpressurization that they show in the reloading manuals. But, I'm not sure I trust myself to make a good judgment on what is acceptable and what's not.
Should I use a chronograph to determine max. load? If so, I'm not sure I understand how that correlates to a safe max. load.
Thanks for your help, Neil

 

[shadowalker]

A chronograph can give you an idea based on your velocity vs published velocity but it is only one of the tools to estimate pressure. Pressure signs may not show up until there is a considerable overpressure.

One of the reasons to start lower is different brands of brass and primers can affect pressure, the same weight and configuration of bullet can affect pressure as well, Speer Gold Dot vs Berry's plated for example.

By starting lower you have a chance to observe pressure signs before it is catastrophic. You also put less wear and tear on the weapon and have less recoil.

It seems like you should probably stay with starting and mid range loads until you are more comfortable. A starting load is far more forgiving of an extra few tenths of a grain of powder than a max load. It also gives you the opportunity to get to know your equipment and pick a few pet powders that you like.

 

[Walkalong]

I you get to max in a load book, stop.

A chrono can help by giving you an idea of when adding more powder is no longer giving meaningfull gains in velocity. Stop there regardless, you are not getting any gain. Useing the chrono to check velocity is a good way to stay safe. There is no free lunch. If you are getting 100 or 200 FPS more than manuals show, you are probably over pressure limits. If the max load does not give you the velocity you think it should or you want, stop, change powders and try again.

 

[The Bushmaster]

Let's see...Over pressure signs:

1..Cratered primers.
2. Ruptured primers.
3. Primers that show signs of flowing into the firing pin hole.
3.a. Flattened primers are NOT an indication of an over pressure load unless
they exibit signs of 1, 2 or 3.
4. Ballooned cases. Particularly if fired in an auto loader other then a Glock.
5. Cases that are hard to extract from a revolver or rifle chamber.
6. Exceedingly loud report or overly heavy recoil.
7. Pieces of the gun scattered over the area...A prime indication of an
over pressure load.

O K...What did I leave out???

 

[ATAShooter]

You will also find that the hotest round sometimes, ain't the most accurate. I have loaded .308 rounds and then after backing off, got better groups.

 

[Walkalong]

By the time you see cratered primers etc. you have gone too far. Work up slow.

Yes, I have cratered primers. Yes, I blew (severely) a primer once trying to use Blue Dot for reduced loads in the .22 Hornet.

Very position sensitive. I found a nice reduced load with 700X.

 

[USSR]

Should I use a chronograph to determine max. load? If so, I'm not sure I understand how that correlates to a safe max. load.

Yes, a chronograph, knowing what are obtainable velocities, as well as reading the pressure signs as outlined by The_Bushmaster.

Don

 

[TooTaxed]

I'm with ATASHOOTER. If you test small batches with slightly increasing powder charges for a given bullet, you'll probably find that wider groups is the tradeoff for higher velocity/pressure. This is readily evident in pistol ammunition, but also works in rifle. The full tilt/boogy loads are also rougher on you, the gun, and the brass...

 

[Clark]

You follow the instructions in the load book.

If you get smarter than the load book, you can write your own.