Home Forums Reloading Big Game Rifles Chronograph re MAX LOADS...

I've had that issue and if I wanted the 200 fps or more in velocity, I made a dummy round with the bullet seated out further
and took the rifle over to the gunsmith and had him ream the throat out to fit the dummy round and then
worked up my load once again...

also changing powders can change that if velocity is short of your expectations...

some of my varmint rifles I ratchet up in velocity due to desiring an increase in range with them...

hunting rifles, not really, as I hunt at woods ranges usually.

but I chase accuracy first, velocity second...

also learned which powders are most accurate when redlined and which ones are most accurate at more sedate
velocity....

Guess we all have our own ways we have learned to live with... I know what works for me...
and I won't deny that came about from "learning experiences" along the way...

Load manuals are a guide, not a bible.... and that can be for finding velocity, up or down... along with accuracy.

there are no concrete truths... I just don't try to turn a 308 into a 300 Win Mag.. and life is pretty non eventful...

I work up to book velocities minus the factor for barrel length, assuming pressure signs aren’t showing up. Like others have said, if velocities plateau or even decrease I back off.

A chronograph will tell you a lot about an individual rifle.The throat has a lot to do with how much powder it will handle and different bullets do too.Some rifles you can load over book max and some you cannot.It will also show you how just changing seating depth can really change your velocity too.It's a useful tool for sure.

I'm not sure I completely agree with that. I believe powders are designed to work within certain pressure parameters and when one goes above or below those parameters is when trouble rears it's ugly head.

A prime example would be working with something like one of the 4350's or other slower powders. Go too low and you get a problem with S.E.E., P.E.P, or DDT, pick whichever one you want, that all mean the same. KABOOM! As you increase the powder charge velocity also increases generally in a linear fashion. The mean might be 50 FPS with a plus or minus 10 FPO variance. As one reaches the max load for that individual rifle velocity might make a big jump in speed, no change from the previous load and even have a drop in speed. Checks with pressure ring expansion, case head expansion and even the primer which is usually considered useless as a pressure indicator unless it flat falls out will help determine if max has been reached. Probably have some sign of sticky bolt lift as well.

The point is, while the system isn't perfect, it is at least one way to help keep out of trouble. I've been using it a lot lately while playing with a couple of 7x57s. Loads that are no problem in a Ruger #1 and M70 FWT are way too high for a custom Mauser I have. Depending on the powder used, charges just one or two grains over the minimum load will lock up the bolt or show weird velocity changes. Still trying to figure that one out.
Paul B.
PS: I didn't say the system was perfect, just a help.

I use my chronograph through the whole process from the starting load to the max load. I shoot through the chrony every time I change the weight of the charge. To me speed is one of the pressure signs. I usually get to where I want that way without any other pressure signs. I once got max velocity with the starting load.

I believe the safest way to reload is to regard Velocity, Powder charge, and even unreliable "pressure signs" as stop signs to back away from.

Chronograph loads as you work your way up and if you start exceeding normal velocities for a given caliber/bullet weight/powder combination you are likely to be exceeding normal pressures.

If you start going past maximum loads in reliable pressure tested manuals you are likely also most likely exceeding their pressures.

Lastly if your rifle is showing obvious flattened primers, sticky bolt lift, loose primers or over expanded case heads obviously something is wrong! You usually will run into the one of the first two first.

I also like to look at several manuals. If one manual has a powder charge or velocity way different than the others I look at it very skeptically. Some manuals AREN'T pressure tested and are less reliable than ones that are.

I have a round I load for in 3 different rifles. In ALL three rifles a load 2.5grs UNDER their maximum listed load I get over 200fps ABOVE their listed max velocity! Obviously I'm not going to try and load anywhere near their max load. It also makes me VERY skeptical about some of their other loads since they are by far the highest on several powders and I know that they don't actually pressure test their loads.

I really think they are too many reloaders that think as long as they aren't popping primers and don't have to use a lead hammer to open their bolt they are within safe pressure limits. I talked to too many that think they are somehow magically able to load the same components 200-300fps faster than everybody else without exceeding pressures they should. They are wrong. :-/

Hey stranger, welcome back.

Thanks!

I have always valued Seafire's contributions and respected his opinions. But in this case, I disagree.

The absolute best and most dependable "pressure indication" is a dependable chronograph. No, make that second best. The best is a Pressure Trace device. But they are still a bit spendy and complicated for any but the most serious of hobby reloaders.

Pressure times time does equal velocity. For example: You can not hit 60,000 psi in a 30-06 using H4831 with a 150 gr bullet without getting well past 3000 fps.

On the other hand if you have hit 2900 fps with a 180 gr bullet in the 30-06, you are at or over max pressure no matter which powder you have used.

We have been discussing traditional pressure indicators on this forum for many years. We have compared pressure ring expansion, case head expansion, primer flattening, primer cratering, The closest thing to a consensus is that none of these indicators can be depended upon to appear before your load has already passed Into the danger zone.

I measured and recorded case head expansion for several years. When measuring 20 identical loads in virgin brass gives CHE reading from .0005 to .0025 in cartridge after cartridge and caliber after caliber, one begins to understand what Denton means when he tells us the practice produces too much noise to be of any real value.

My reloading practices evolved to this:
I pick my cartridge and bullet, then with the assistance of the loading manuals I choose a powder which will produce maximum velocity for the bullet chosen and load to 95% to 105% load density. I love compressed loads! One of my favorites for the 30-06 was 63 gr H4831 in Lake City 67 brass with a 165 gr ballistic tip.

After selecting cartridge, bullet, and powder, I set up the chronograph and grab a tablet of graph paper. Starting at book minimum, I graph velocity vs charge weight. You are looking for a nice straight line "curve" with dots not straying too far from the curve. When dots start departing from the curve at the top end, whether above or below the line, the load is at maximum pressure.

Of course, one will watch velocity. One knows what velocity to expect at SAAMI max pressure, from his load manuals. There is no free lunch. If your velocity is above max speed shown in the manual with your powder,then your pressure is also above max.

With my rifles, the rule has been with very few exceptions, they are slower than the book suggests. I often load several grains above book maximums. But as long as my MV is in line with book maximum, adjusted for barrel length, I know my pressure is okay.

The one traditional pressure sign I depend on is tight primer pockets. If the primer still seats with good resistance using my Lee Auto Prime after ten reloads, it is definitely a safe load. If the primer starts falling out after six or seven loads, it is too hot.

Excellent advice Idaho_Shooter!