Bullet seating depths

Mikecr

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It can change MV with a significant step as you near touching of lands.
It can greatly affect POI, and grouping.
You should do Berger's recommended full seating testing.
 

Hard rock

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Some bullets are mor fi
Yes, but it’s greatest effect seems to be group diameter.
Some bullets are more finiky too seating depths than others I usually find my max overall with what ever bullet of choice move away from lands around . 20 and work from there that way there's only one way too move unless your loading touching lands if touching lands back off powder charge and work back up safely
 

Longtine88

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If you develop a load with a certain powder charge and a certain COAL and you are wanting to seat the bullets deeper and deeper trying to find a sweet spot your powder charge will get more compacted and hence a higher velocity and pressure. I generally back off just slightly as I go down with the seating depth to get back to my initial powder velocity. If will do the same pressure building when you get into the lands. It shouldn't do it so much before your length is approaching the lands though. It may actually decrease some until lands are touching and you start running the bullet into the lands.
 

Okanogan

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Especially when I'm trying to load subsonic, I find it makes a huge difference. Some powders like 300 BLK really like a compact charge and are hard to get consistent MV without being compact. While it isn't mentioned too much on this long range focused forum, seating depth can also greatly affect the ability of a semi-automatic to feed properly.
 

DWier

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Berger Hybrid and Hammers are the easiest to load. Give at least .020 + and they don't care. I've heard of 0.500 jump on Hammer Hunters shooting well. But not personal experience.
I'm sure ButterBean will jump in on this.
 

MW204

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Berger Test

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event that must be avoided)


1. .010 off the lands (jump) 6 rounds
2. .050 off the lands (jump) 6 rounds
3. .090 off the lands (jump) 6 rounds
4. .130 off the lands (jump) 6 rounds


Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005. Taking the time to set this test up will pay off when you find that your rifle is capable of shooting very well.
 

Hard rock

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Dec 20, 2020
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710
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Tomball Texas 77377
Berger Test

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event that must be avoided)


1. .010 off the lands (jump) 6 rounds
2. .050 off the lands (jump) 6 rounds
3. .090 off the lands (jump) 6 rounds
4. .130 off the lands (jump) 6 rounds


Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005. Taking the time to set this test up will pay off when you find that your rifle is capable of shooting very well.
Touching the lands used to be the best way too go for your best accuracy when I started loading 50 yrs ago thats what I allways did but today things are a little different with monos etc so now in the lands or off the lands may work best you just have to play with seating depth and find out the hammer bullets seem too be real versatile with a lot of jump or closer to the lands that really helps with these mag lenght restrictions
 

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