I'm loading some 175 smks in some mil brass. I think i'm on the 4th or 5th loading in these cases. I've neck sized them twice and full length sized them twice. the bolt was getting a little tight on the last loads so I full length resized on this go around. Since full length resizing i'm getting .015 swings in seating depth on a comparator which seems odd. Seems to me the last time i neck sized they were dead on. seems to me this isn't normal. What am I missing?
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Wide swings in seating depth
- Thread starter Norseman1950
- Start date
In my bolt guns I set my shoulders back .001-002. Setting your shoulders back as much as .009 will run the risk of case head separation..What measuring tools are you using to determine how far you are pushing the shoulders back..Ray
Larry Willis comparator. I have hornady full length dies. Tried just bumping the shoulder a couple thousandths but it made the neck bulge. Guess I could have tried running them through the neck sizer after but didn't think if that until just now.
Regardless of the case length. The comparator is nothing more than the measurement between the base of the case and the ogive of the bullet correct? Case length shouldn't effect this measurement correct?
0.015 difference in seating depth is a huge amount. Are you sure the comparator is picking up the same spot on all the bullets? Try measuring coal. That should vary by a similar amount probably not exact but you'd know if it was 10-15 thou off vs 1-3 thou off.
If the bullets are truly seating to a different depth, I would look at the die and press. If the press is traveling the same amount and the die/stem is stopping the bullet at the same place then the seating depth should not vary by .015.
The only other thing that could potentially stop and or move the bullet would be the powder. But even then I can't imagine light enough neck tension to allow the bullet to be pushed back out .015 or a so completely compressed load that the mechanical advantage of the press wouldn't crush it and seat fully each time...but you could dump the powder from a couple rounds and seat them to eliminate that possibility.
If the bullets are truly seating to a different depth, I would look at the die and press. If the press is traveling the same amount and the die/stem is stopping the bullet at the same place then the seating depth should not vary by .015.
The only other thing that could potentially stop and or move the bullet would be the powder. But even then I can't imagine light enough neck tension to allow the bullet to be pushed back out .015 or a so completely compressed load that the mechanical advantage of the press wouldn't crush it and seat fully each time...but you could dump the powder from a couple rounds and seat them to eliminate that possibility.
Yes, with the bullet comparator bushing in. They also make bushings for the case shoulders which are the head space comparators. You'll want those that measure off the shoulder and adjust the die down so that the fired to sized measurements are .002 difference. As stated before moving it .009 will lead to much accelerated brass life. Like 4.5x as much wear.
Its mil brass. Are we sure that it's all the same sort of brass and that you don't have all sorts of different pieces leading to all sorts of different lengths sizes thicknesses pressures etc? I could see that leading to the issue but I figure you would have seen that in your earlier measurements as well.
Just guessing here, but I once had some inconsistency in seating depth between lots of SMKs. I don't use a meplat trimmer. I got some bullets that were just a bit longer and the point bottomed out in my seating die. Any change in bullet length was reflected in OAL. Drilled the seated a bit deeper and problem solved. Just a thought.
Sizing too much and lack of annealing. Two huge points there.
forgot to add neck tension differences from annealing so a double whammy there
forgot to add neck tension differences from annealing so a double whammy there
