Seating die

[horsepower]

I want to seat my bullets close to the ogive/bearing surface junction. My .308 RCBS die stem fits my .277 bullets well, but the 308 stem will not fit into the 270 die. Same with Redding.

Does anyone have a solution they use to accomplish this?

Thanks

[Dean2]

Originally Posted by horsepower

I want to seat my bullets close to the ogive/bearing surface junction. My .308 RCBS die stem fits my .277 bullets well, but the 308 stem will not fit into the 270 die. Same with Redding.

Does anyone have a solution they use to accomplish this?

Thanks

In general, the whole seating stem can be swapped from one die to another easily. You will need to explain better what isn't fitting. If I am reading this right the .277 seating plug fits your current bullet better and pushes down on the ogive rather than the tip and this is why you want to swap stems.. You can also order custom seat plugs for different bullets, The seating plug can also be swapped out of the die from one stem to another.

[Pathfinder76]

RCBS stems may not swap. Redding stems swap easily.

[Faststeel]

Originally Posted by horsepower

I want to seat my bullets close to the ogive/bearing surface junction. My .308 RCBS die stem fits my .277 bullets well, but the 308 stem will not fit into the 270 die. Same with Redding.

Does anyone have a solution they use to accomplish this?

Thanks

Crank you threads up as high as they'll go and seat with your 308 die.....

[horsepower]

Chuck:
I was mistaken when I added Redding, I was thinking something else. I will try the Redding stem swap when I get back home.

Dean:
You are correct. I want to push down on the bullet at the same place where I measure my bullets from.

I think a 338 seating stem would push down on a .30 cal bullet closer to where I measure. I may have to drill out the stem to accommodate bullet nose changes but that is ok.

[260 Rem]

Interested in why you want the seater stem to contact the bullet ogive so far from the tip?

[obsessed1]

Originally Posted by 260 Rem

Interested in why you want the seater stem to contact the bullet ogive so far from the tip?

/\ /\ wondering the same. Why does it matter??

[Pathfinder76]

It offers more depth consistency and concentricity.

[260 Rem]

Originally Posted by chuck

It offers more depth consistency and concentricity.

Never heard that theory before. Wonder why die makers haven’t improved their seating stems accordingly? The only factory modification to seater stems that I am familiar with are the VLD stems available with the Wilson In-line...and they do not seem to contact any deeper on the ogive. Personally, I would not try to open up a seater stem without precision equipment for obvious reasons.

[horsepower]

Originally Posted by chuck

It offers more depth consistency and concentricity.

Correct. This is the new to me theory I want to work on. I have found the "bullet bearing surface to tip" transition to be inconsistent. This makes for inconsistent measurements.

If I use a comparator and measure base to ogive, it then makes sense to seat my bullets from that same location. This should result in consistent length

If my bullet seater seats on the bullet closer to the tip (which they do) then my original measurement has little meaning. It is not uncommon to seat 5 bullets and have 5 different COAL's. My tools have not moved, the noses of the bullet have slightly different shape. I believe this to be inherent inaccuracies during manufacturing process.

Not important for hunting, but I'm playing on an idea.

[Pathfinder76]

https://youtu.be/ECUcIeak7CM

[horsepower]

Thank you Chuck. I started to think about this last hunting season and have since found out that people have been discussing this for many years. Hence, "new to me". David Tubb illustrates the inconsistencies well in the video.

I spoke with a gentleman today who uses a Lyman or RCBS decapping die and "builds" a seater that specifically works for each cartridge and bullet. I have to put some thought into this.

I would like both my bullet measuring tool and bullet seater touch the bullet at the same place. I would like that place to be at the same ID as my bore (not lands), or close to it.

[260 Rem]

I could have missed something, but it seems Tubb is suggesting bullet jackets become more “consistent” from tip to “back” ... and on that basis, he is promoting his “modified” seater stem?

[catnthehat]

Three of the things I was taught when I first started hand loading as a kid were
A: the condition and consistency of the the base of the bullet is far more important to accuracy than the point .

B: overall length from the ogive to the base of the cartridge is far more important to accuracy than the overall length from the point of the bullet to the base of the case .

C: even match bullets often vary a bit in overall length when measuring from ogive to base
Several die manufacturers sell different seating stems for a particular caliber and I make a point of checking to make sure the stem I am using for a particular bullet contacts the ogive and does not bear on the point itself and often change things up when using different stems
Cat

[6.5 shooter]

Originally Posted by 260 Rem

I could have missed something, but it seems Tubb is suggesting bullet jackets become more “consistent” from tip to “back” ... and on that basis, he is promoting his “modified” seater stem?

yes

I am not sure the average shooter would notice the difference...but like archery consistency is key.

[catnthehat]

Originally Posted by 6.5 shooter

yes

I am not sure the average shooter would notice the difference...but like archery consistency is key.

Most shooters and hunters will not notice the difference for sure and especially under hunting conditions .
Under benchrest conditions, yes .
I don't actually worry about it except for my long range match rifles .
I was taught however , that those are basic facts , not that they are mandatory to be able to shoot say, 1/2MOA at 100 yards !
Cat

[obsessed1]

Great now I have another rabbit hole to jump down....thanks guys does anyone make true caliber sized seaters? Or would one need to find the closest and machine it open a bit to get perfect? Would be looking for 30 cal to start with

[catnthehat]

Originally Posted by obsessed1

Great now I have another rabbit hole to jump down....thanks guys does anyone make true caliber sized seaters? Or would one need to find the closest and machine it open a bit to get perfect? Would be looking for 30 cal to start with

Not so much caliber sizes but bullet types in a particular caliber .
For example I know Hornady sell different stems for 6.5 caliber .

Bullets pointing is another aspect of this as well to uniform bullets so they are the same length .
Cat

[Wrongside]

Originally Posted by horsepower

I want to seat my bullets close to the ogive/bearing surface junction. My .308 RCBS die stem fits my .277 bullets well, but the 308 stem will not fit into the 270 die. Same with Redding.

Does anyone have a solution they use to accomplish this?

Thanks

One of the reasons I've gone to Forster Benchrest Seaters for almost every caliber I load.

[obsessed1]

I use lee dies for seating generally. I measure with rcbs precision Mic. And check run out with the hornady run out tool or the rcbs case measure tool. With the lee dies for my precision LR rounds my habit is seat in short strokes rotating the round 1/4 turn each stroke until seated. My tests have proven less than .001 run out / batch and less than 10% have that much. My seating depth measured with the precision Mic is less than +-.001 in the 100 rounds I just measured. Would changing out the seating die make much difference?
Rounds measured are 300 wm . Winchester cases. 208 gr hornady eldm bullets. This gun groups under 1/2 moa with these hand loads.

[260 Rem]

Originally Posted by obsessed1

I use lee dies for seating generally. I measure with rcbs precision Mic. And check run out with the hornady run out tool or the rcbs case measure tool. With the lee dies for my precision LR rounds my habit is seat in short strokes rotating the round 1/4 turn each stroke until seated. My tests have proven less than .001 run out / batch and less than 10% have that much. My seating depth measured with the precision Mic is less than +-.001 in the 100 rounds I just measured. Would changing out the seating die make much difference?
Rounds measured are 300 wm . Winchester cases. 208 gr hornady eldm bullets. This gun groups under 1/2 moa with these hand loads.

And that is the reason I’m not following anybody into the hole. Same concept as “over stabilizing” a bullet ... once stable, it just can’t get any more stable ...nor can a cartridge with virtually “0” runout get any more concentric.

[catnthehat]

Originally Posted by 260 Rem

And that is the reason I’m not following anybody into the hole. Same concept as “over stabilizing” a bullet ... once stable, it just can’t get any more stable ...nor can a cartridge with virtually “0” runout get any more concentric.

Yup, one of those rabbit holes not worth going down in most cases, but nice to know anyway.
Cat

[obsessed1]

Originally Posted by 260 Rem

And that is the reason I’m not following anybody into the hole. Same concept as “over stabilizing” a bullet ... once stable, it just can’t get any more stable ...nor can a cartridge with virtually “0” runout get any more concentric.

Seems like it's not a rabbit hole I should be jumping down with this rifle/ ammo either. Just wondering if anyone has actual data on accuracy/ precision increase going this route

[catnthehat]

Originally Posted by obsessed1

Seems like it's not a rabbit hole I should be jumping down with this rifle/ ammo either. Just wondering if anyone has actual data on accuracy/ precision increase going this route

Three of us some tests years ago with some match rifles and inside 500 meters found it wasn't really worth worrying about , those records were with Okd Badger who has gone to quieter ranges however .
I also read some articles about it in Precision shooting years ago before the Internet was big .
The person who taught me how to hand load worked in cartridge investigations and the R&D department of C.I.L., and I don't have any of that data either .
Cat

[Dean2]

If you think about it logically getting to zero Ogive Length variation in seating depth can only have one result, effect on velocity variation. Decreased variance in the jump to the lands and making internal volume just ever so slightly more consistent are the results. The only place this will show up, if it makes any difference at all, is in velocity variation, which should be reflected in ES and SD. So the easy test is to see if the zero variance results in lower SD and ES than the exact same load with the typical .002-.004 variability in this dimension induced by most seating stems. One could intentionally induce even larger variation to further test the effect. Even if it does reduce ES and SD you probably aren't going to see any difference in vertical till you get to 800 and beyond, unless the SD reduction is truly large and I doubt seating depth consistency within the normal range is capable of that big a change.

[6.5 shooter]

Originally Posted by Dean2

If you think about it logically getting to zero Ogive Length variation in seating depth can only have one result, effect on velocity variation. Decreased variance in the jump to the lands and making internal volume just ever so slightly more consistent are the results. The only place this will show up, if it makes any difference at all, is in velocity variation, which should be reflected in ES and SD. So the easy test is to see if the zero variance results in lower SD and ES than the exact same load with the typical .002-.004 variability in this dimension induced by most seating stems. One could intentionally induce even larger variation to further test the effect. Even if it does reduce ES and SD you probably aren't going to see any difference in vertical till you get to 800 and beyond, unless the SD reduction is truly large and I doubt seating depth consistency within the normal range is capable of that big a change.

I agree... but then the next"issue" is the chasing of the lands as they slowly move away from the bullet....yes It may take many rounds for this to happen but when we finally decide we have the perfect solution..another variable raises its nasty head...

Mostly the loose nut behind the gun is the biggest factor in whether accuracy is ..good enough.