I know the pressure reading you see is dependent on a lot of things like bullet diameter, neck tension, brass hardness, neck wall thickness.. etc.. Just wondering what your goal is for an average seating force and acceptable range for long range ammo? Mainly interested in 6mm/243 and .308 cal. Thanks!
K&M press pressure goals
- Thread starter jccinohio
- Start date
RegionRat
Gold $$ Contributor
@jccinohio , You ask a fair question, but think of it the other way around...
Keep good notes and when you find a prep recipe that gives you good groups and makes you happy, then running the K&M data alongside as a QC check will tell you if your prep is drifting out of tolerance or if an individual round is a defect.
There isn't a universal answer for seating force, because there is more than one philosophy for seating.
Will you jam with enough neck tension to hold the bullet, or will you jam with light neck tension and allow the bullet to "self seat"?
Will you jump?
Will the rounds be re-seated after some long distance travel?
Will your rounds need to be sturdy enough for magazine feed, or are they single feed?
Even narrowing the discussion to 243/308 isn't narrow enough unless you put the seating force into the context with all those other questions.
Needless to say, you are about to get answers from very low (say 15 - 20 lbs) to very high (say above 100 lbs).
Some answers represent lube in the neck prep or moly coated bullets, some are squeaky clean brass with plain bullets. Those friction coefficients are equally important to neck prep and have a strong effect on the answer.
Nothing wrong with a discussion on seating forces, but remember to keep perspective on how wide those values can be if not put into context.
Keep good notes and when you find a prep recipe that gives you good groups and makes you happy, then running the K&M data alongside as a QC check will tell you if your prep is drifting out of tolerance or if an individual round is a defect.
There isn't a universal answer for seating force, because there is more than one philosophy for seating.
Will you jam with enough neck tension to hold the bullet, or will you jam with light neck tension and allow the bullet to "self seat"?
Will you jump?
Will the rounds be re-seated after some long distance travel?
Will your rounds need to be sturdy enough for magazine feed, or are they single feed?
Even narrowing the discussion to 243/308 isn't narrow enough unless you put the seating force into the context with all those other questions.
Needless to say, you are about to get answers from very low (say 15 - 20 lbs) to very high (say above 100 lbs).
Some answers represent lube in the neck prep or moly coated bullets, some are squeaky clean brass with plain bullets. Those friction coefficients are equally important to neck prep and have a strong effect on the answer.
Nothing wrong with a discussion on seating forces, but remember to keep perspective on how wide those values can be if not put into context.
Not to be picky but, the K&M force pack indicates force, not pressure. Pressure is lb-force per unit area, usually square inches.
I've taken a close look at how much force it takes to pull a seated .264 bullet, the peak value was about 30 lb-force if memory serves. The seating force was roughly double that at 60 lbs. Using the cross sectional surface area of a .264 diameter bullet, I shade-tree calculated the pressure equivalent; 30 lb-force applied to .055 square inches, that's about 545 PSI needed to push a bullet from the neck.
Using QuickLoad, I tried to find 545 PSI on the predicted pressure curve; my eyes aren't that good, lol. Finding such a tiny amount of pressure, 545 PSI, in a peak 60,000 PSI, instant explosion, is looking for the needle in the proverbial haystack.
My assumptions may be incorrect of course, and I still obsess over consistent seating force
.
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