Loading Barnes LRX for the first time

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RichardSlinger

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Good morning all,
I'm looking for some guidance from those that have experience loading monolithic bullets I'm loading them for the first time.

I've always been under the impression that the deeper you seat bullets the more pressure increases because you now have less case capacity.
Barnes recommends that you seat them with a min of 0.05" of jump or you may have dangerous pressure levels.
This seems counter-intuitive to me because by seating them deeper you'd have less case capacity.

Am I wrong in my assumption?
The load I have now is pretty accurate but there's no jump at all, it's seated to touch the lands.
I wonder if that's such a good idea, it's a pretty hot load.
 
You should use a big jump. Barnes is correct. I’ve loaded for the 270 and the 6.5x65 and pressure is too high with small jump. Blown primers, excessive case head expansion were my symptoms.
Accuracy improved as jump increased.
 
Mono bullets are made of a harder material that standard bullets so need that jump to gain enough speed to cut into the rifling. If not the pressure builds trying to force it into the lands. Mono are also made from lighter material so are typically longer for weight as well so you also lose capacity there.

Good luck.

SCG
 
For the same load of powder, The pressure is max when a bullet touches the rifling as the gas has no place to expand in the throat. Seating the bullet deeper, 30-60 thousands, while decreasing the pressure compared with when jamming the bullet, will give usually the best accuracy and good but lower pressure than in the former case as the gas will expand in the throat also. Seating much deeper will increase the pressure in the case more than the expansion in the throat can compensate for, therefore you might obtain higher pressures again. Briefly the relationship between seating depth and pressure in not linear. It is a parabola (without being pedantic).
 
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mimile said:
For the same load of powder, The pressure is max when a bullet touches the rifling at the gas has no place to expand in the throat. Seating the bullet deeper, 30-60 thousands, while decreasing the pressure compared with when jamming the bullet, will give usually the beast accuracy and good but lower pressure than in the former case as the gas will expand in the throat also. Seating much deeper will increase the pressure in the case more than the expansion in the throat can compensate for, therefore you might obtain higher pressures again. Briefly the relationship between seating depth and pressure in not linear. It is a parabola (without being pedantic).
Click to expand...

This makes sense thanks for that, I worked on a load all summer for my upcoming moose hunt, shot great but I was uncomfortable with the velocity I was getting.
I then dropped the powder charge 0.5gr it shot so-so and I'd see wild flyers every now and then.
Next, I loaded the same powder charge (0.5gr less than my original load) seated 0.05 deeper.
What I saw then was out of a 5 shot group, three bullets would cluster within an inch of one another and two others would shoot 2.5 sometimes 3" higher.
I saw this pattern over the 3 x5 shot groups I shot, this with a 5min cooldown period between every shot.

Those shots that went high set alarm bells off in my mind, perhaps erratic pressure spikes are causing it who knows.
I think the best thing to do is to put this on hold until after hunting season. then start over with enough jump and a much lower powder charge and go from there.
 
You could chronograph your seating depths to see if you get more pressure (higher speed) or not. I would guess your getting inconsistent speeds (pressures) as you rifle, load and seating depth are not in the sweet spot that works. Or that amount of jump is inconsistent in your setup.

Or I am wrong. Lol

SCG
 
iron cat said:
With the mono metals I usually end up between o.060 and .090 off the lands. One rifle is a full.125
The majority of them are shooting better than 1MOA at 200 yards.
Cat
Click to expand...

I'll keep this in mind, I think I'll start building a new load this winter seat .060 off the lands and use a modest powder charge.
 
iron cat said:
I use about 1 grain less than max as a rule and never had an issue. I see I made a mistake in my previous post - it should read 1INCH not 1MOA!!:p
Cat
Click to expand...

One grain under max, is that with monometal bullets only or is that a general rule of thumb Cat?
I saw somewhere that you typically play with seating depth rather than charge weight.
 
RichardSlinger said:
One grain under max, is that with monometal bullets only or is that a general rule of thumb Cat?
I saw somewhere that you typically play with seating depth rather than charge weight.
Click to expand...
Yup that is with any bullet. And yes you are correct, I adjust my seating depth before my max charge .
With the larger cases I generally do not go quite so high, but with 308 sized cases I rarely have issues with 1grain under the average max load. I day average because I look at several
books and Quickload as well , to figure out that charge.
Cat
 
iron cat said:
Yup that is with any bullet. And yes you are correct, I adjust my seating depth before my max charge .
With the larger cases I generally do not go quite so high, but with 308 sized cases I rarely have issues with 1grain under the average max load. I day average because I look at several
books and Quickload as well , to figure out that charge.
Cat
Click to expand...
Very helpful thanks, I’ve always gone powder charge first then seating, but I rarely needed to mess with seating before. I’d get decent accuracy before I had to fiddle with seating and called it good.

The rifle I have now is quite picky it seems, got to load it just so.
I think I may just switch to your way of doing things with this rifle.
 
RichardSlinger said:
Very helpful thanks, I’ve always gone powder charge first then seating, but I rarely needed to mess with seating before. I’d get decent accuracy before I had to fiddle with seating and called it good.

The rifle I have now is quite picky it seems, got to load it just so.
I think I may just switch to your way of doing things with this rifle.
Click to expand...
I think you will be pleasantly surprised!
Cat
 
Seating deeper reduces case capacity which will boost pressures with a given charge weight. But it also increases freebore, which reduces pressure. It's more or less a wash

I go .050" with monometals, or as close to this as I can get and still fit in the mag box of the rifle.
 
todbartell said:
Seating deeper reduces case capacity which will boost pressures with a given charge weight. But it also increases freebore, which reduces pressure. It's more or less a wash

I go .050" with monometals, or as close to this as I can get and still fit in the mag box of the rifle.
Click to expand...

Yes,I seen a test where they went from 0.02 to 0.14 off lands. Pressure changes wasnt worth noting.

YMMV

SCG
 
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