7mm RM loading frustration

[Reidus]

I see. That makes more sense. Seems like a pretty safe way to go.

[DaveMonti]

Thanks all for the chronograph explanation!

[huntnphool]

Bobcat,
I realize the chronograph will tell you the velocity, but how does it indicate the max load?  Do the velocities from shot to shot become inconsistent as you go beyond the "max" load?
Just curious, I never heard of using the chrono to determine max load.

You could graph velocity vs. powder charge and it should look like a fairly linear increase.  Then as you reach max powder, you will see the graph flatten out.    There does come a point where more powder does not result in much of a velocity increase.  (There may even be a point where increasing powder results in less velocity.)

This doesn't make sense to me. With certain powder/bullet combos it may work but in some cases I think you will see flattened primers and a sticky bolt before you see a decrease in velocity gain.

You should stop increasing your powder charge once you reach the maximum expected velocity. If you're getting more velocity than the book shows you're most likely also over pressure. If you're seeing over pressure signs with your brass and/or your bolt being hard to open, then you're probably WAY over pressure. Better to stop before you reach that point. This is why a chronograph is very useful.

Good points.

 I'll add that I have been predominately shooting a 7RM for a long time, have more than a couple decent trophies, have never needed more than one shot out to 500 yards and do not run maximum load.

 One of the advantages to the 7mm round is its flat trajectory, without having to go max load.

 Is there a reason why you feel you need to go as hot as you can?

[BULLBLASTER]

If you can safely work up added velocity and not lose accuracy why wouldn't you make it faster? Get all you can.
No reason to shoot lower loads of a hotter load is just as accurate and not over pressure for your particular load and rifle. 
But I agree to keep it conservative so that different conditions won't create unwanted pressure spikes.

[high country]

If you can safely work up added velocity and not lose accuracy why wouldn't you make it faster? Get all you can.
No reason to shoot lower loads of a hotter load is just as accurate and not over pressure for your particular load and rifle. 
But I agree to keep it conservative so that different conditions won't create unwanted pressure spikes.

if he is new to reloading he may want to consider atmospheric conditional changes that affect the velocity and pressures. A book that was published shooting in cool and high density air will not be the same as those shot in hot conditions. The temperature of the powder plays a big role too, some powders are fairly temperature sensitive.

I stick to suggesting the velocity range that is a known for the cartridge and not pushing it until the shooter knows how to measure the brass for strain.....its not worth it, just hold a quarter inch higher.

[bearpaw]

IMPORTANT: Watch for pressure!

If you get too much pressure you can damage a gun and possibly yourself. Always start with a low load and work up. Every time you shoot a load with a little more powder or a change of primer or change of bullet you need to inspect your spent case.

One of the first signs of pressure is flat primers. One of the next signs is a dimple from the firing pin, if you rub you finger nail across the primer and feel an edge where the primer struck that is caused by pressure. Check for case length stretching and for splits in the case too. If you see any of these signs it's time to stop and probably back off the powder.

[BULLBLASTER]

If you can safely work up added velocity and not lose accuracy why wouldn't you make it faster? Get all you can.
No reason to shoot lower loads of a hotter load is just as accurate and not over pressure for your particular load and rifle. 
But I agree to keep it conservative so that different conditions won't create unwanted pressure spikes.

if he is new to reloading he may want to consider atmospheric conditional changes that affect the velocity and pressures. A book that was published shooting in cool and high density air will not be the same as those shot in hot conditions. The temperature of the powder plays a big role too, some powders are fairly temperature sensitive.

I stick to suggesting the velocity range that is a known for the cartridge and not pushing it until the shooter knows how to measure the brass for strain.....its not worth it, just hold a quarter inch higher.

Good info. One test I like to use for pressure is to get a round all wet and load and fire it. The water will take up some chamber space and cause higher pressure. Which may show symptoms if the load is on the edge.

I don't mean to say everyone needs to hot rod their loads but at the same time don't see the reason to leave velocity on the table. But at the same time 50 or even 75 fps isnt a real big deal. Even at longer range. I try and be near the max published velocity. Corrected for barrel length if different. I figure 30-40 fps per inch is a good rough idea

[bobcat]

I try to at least match the velocity of factory loaded rounds. I feel like if I'm taking the extra time to handload there's no reason I shouldn't be able to match the speed of the stuff I buy at Walmart. I normally only exceed those velocities by 50 to 100 fps.

[jamesjett]

I've been loading for my 7mm for over 20 years and bullet seating depth seems to be the biggest factor in accuracy.  Measure the lands to ogive for each differerent bullet you want to experiment with. Some like it .020 off and Barnes love them about .060 - .080 off the lands. 

[rudysts]

I've been loading for my 7mm for over 20 years and bullet seating depth seems to be the biggest factor in accuracy.  Measure the lands to ogive for each differerent bullet you want to experiment with. Some like it .020 off and Barnes love them about .060 - .080 off the lands. 

I agree seating depth matters in any rifle and bullet powder combination it can also change your pressures higher or lower.
In the past year I have been using Quickload software for reloading and it is saving me money on components, I am able to identify a powder bullet combination with predicted pressures and velocity with this program.

[Piscatory_5]

If you want to see how recommended maximum loads are all over the place, find some of the old books from the 60's and 70's and see what those maximum loads were.

You'll find out maximum load recommendations are way more cautious these days.

Indeed, I have a Lyman book from that era, given to me by my father with the words,  "be careful of max loads in that book they are hot". Be sure and check what firearm they tested the loads in and barrel length as well. Universal receiver and 26" barrel will not be the same as Remington 700 mountain rifle with 22" barrel.

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