Today i was loading up rounds for load development for mr AR. I was getting a wide range of OAL from 2.239 to 2.257 loading 77gr otm. I was aming for 2.25. My equipment is a lyman turret press and using a hornady micro adj setting die. The turret is on tight as it can get. Is the difference from the bullets not being all uniform or is it tension when seating. I do anneal my brass as well. Even though its just AR loads I wanna learn as much as i can before i step into the bolt action world and waste potential money. Thanks again for any info.
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Need some guidance and advice for seating
- Thread starter Kangbeef
- Start date
Some of it is undoubtedly difference in ogive-to-tip length from bullet to bullet. Get yourself a bullet comparator so you can measure from cartridge base to ogive (CBTO) instead of OAL and your numbers should improve (it won’t mean your ammo is better, only that you can measure it better).
First, it's common to have bullet OAL variances, like anywhere from .004 to .010 depending on the quality of the bullets you're using. Unless you shooting ELR, bullet OAL is not really much of a big deal. But, seating depth consistency is a big deal and that's often measured by the CBTO (Cartridge Base To Ogive). I've found the best way to get consistent seating depth, is to sort my bullets by BTO (Base To Ogive) using a comparator that has the same diameter (or contact point) as the seating stem in the seating die. There are variances between where the typical comparator contacts the ogive and where the seating stem makes contact with the ogive. Sorting this way assures very little variance in seating if your press is capable of seating consistently.
Turret presses are not the best tool for getting consistent seating. So, I think this can be adding to issue you're having with your COAL's. And yes, there could be an additional issue with tension that's adding to that. Even the seating die itself that you have could be adding to the issue. Yep, a chain of things can all be adding up to that one issue and each needs to be addressed.
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Suggesting sorting bullets by BTO for mag length AR ammo is fairly ludicrous, frankly.
For the OP: it might be worth checking where the seating stem is actually touching the bullet. You can either color the ogive with a sharpie and see if the die leaves some marks on the bullet towards the tip (see the pic above for where). Alternatively, you can disassemble the die, take the seating stem and see how it fits the bullet. If the bullet sits down in the stem evenly, the problem isn't there (probably). If it wobbles and is only touching at the point, not back along the ogive... then you need to either modify or replace the stem with one more appropriate for the bullet being used.
Large variations in neck 'tension' (due to things like mixed head stamps) or the surface condition of the neck ID (clean, dirty, maybe some have lube, some don't) or even the case mouth (trimmed, not trimmed, varying amounts of chamfer) can all affect how the bullet seats. You don't need an AMP press to be able to feel most of this - if you can feel some bullets seating harder than others, stop and figure out *why*.
For the OP: it might be worth checking where the seating stem is actually touching the bullet. You can either color the ogive with a sharpie and see if the die leaves some marks on the bullet towards the tip (see the pic above for where). Alternatively, you can disassemble the die, take the seating stem and see how it fits the bullet. If the bullet sits down in the stem evenly, the problem isn't there (probably). If it wobbles and is only touching at the point, not back along the ogive... then you need to either modify or replace the stem with one more appropriate for the bullet being used.
Large variations in neck 'tension' (due to things like mixed head stamps) or the surface condition of the neck ID (clean, dirty, maybe some have lube, some don't) or even the case mouth (trimmed, not trimmed, varying amounts of chamfer) can all affect how the bullet seats. You don't need an AMP press to be able to feel most of this - if you can feel some bullets seating harder than others, stop and figure out *why*.
Hmmm??? Pretty hard to feel some differences in seating pressure when using a turret press. But if you can, then the difference in what is felt tends to be significant.
IMHO...77 smks need to be sorted by coal, they are vary inconsistent.
Next, load cases from batches of sorted bullets.
Aim for 2.26, but pick your longest case out of like 5x sample size to set your seating die (the other 4 will be shorter, ie 2.25 etc).
this is usally pretty reliable method byt ymmv
Next, load cases from batches of sorted bullets.
Aim for 2.26, but pick your longest case out of like 5x sample size to set your seating die (the other 4 will be shorter, ie 2.25 etc).
this is usally pretty reliable method byt ymmv
I have a rcbs single press i will try that on the next round of loading. I will also grab a comparator and sort some bullets in the next week. I can take apart my seater tomorrow and give it a good look over. Thanks again to all for your info.First, it's common to have bullet OAL variances, like anywhere from .004 to .010 depending on the quality of the bullets you're using. Unless you shooting ELR, bullet OAL is not really much of a big deal. But, seating depth consistency is a big deal and that's often measured by the CBTO (Cartridge Base To Ogive). I've found the best way to get consistent seating depth, is to sort my bullets by BTO (Base To Ogive) using a comparator that has the same diameter (or contact point) as the seating stem in the seating die. There are variances between where the typical comparator contacts the ogive and where the seating stem makes contact with the ogive. Sorting this way assures very little variance in seating if your press is capable of seating consistently.
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Turret presses are not the best tool for getting consistent seating. So, I think this can be adding to issue you're having with your COAL's. And yes, there could be an additional issue with tension that's adding to that. Even the seating die itself that you have could be adding to the issue. Yep, a chain of things can all be adding up to that one issue and each needs to be addressed.
Ran a batch of brass from resizing to seating on the rcbs press and i belive I had better results. Resizing seamed more uniform when i went to trim, chamfer them check with case gauge. Then seating didnt have crazy swings in seating depth still some. Bullet comparator is on the way thanks again
