Thread: Using comparator tool when seating projectiles.

Originally Posted by Micky Duck

your looking at it wrong..... the seating die seats all projectiles by the bit of the olgive/curved front half at the same fatness area for want of better term...it will be at same fatness reguardless of projectile shape even a round nose but of course that will be really close to tip...with my 170grn rn in .270 I need to back the die well out to seat projectile as cant lift seater stem high enough.

Nah, he’s looking at it right. Given that the seating stem contacts between ogive and tip, if there is any variance in the ogive profile between the projectiles, you’ll get different CBTO lengths.

understood.....what Im saying is that if you already have a load that shoots well in your rifle..eg in my case factory 130grn old school silver tip in .270

when I set up seating die using that for other spitzer projectiles the difference in olgive shape /how curvey the front bit of projectile is, isnt a huge deal as the ring that contacts..be it 4.5mm or what ever will be same distance from base of case and same distance from start of rifling..so the only difference in rounds over all length or distance to rifling is going to be tiny...that 4.5mm might be at worst 1mm either way on different projectile.... you multi ladder testing types will be reworking load after changing component anyway so point is moot..if your using the SAME projectile that 4.5mm ring will be in the same place....

Originally Posted by 6.5 CRD

Personally i wouldnt worry about trying to measure to the lands with a Hornady OAL tool, I have always just loaded a projectile long in an empty case, tried it in the rifle with a bit of vivid on the ogive and just progressively seated it deeper in the case and kept trying it in the rifle till the bolt finally closes nicely & faint mark of rifling on the vivid. Measured that BTO then knocked it back another 10 thou and started from there. At the end of the day you had a load that was working well in that gun most of the time with the issue being inconsistent seating depth due to measuring COAL rather than BTO. I would load a round at your original powder charge and COAL, use Hornady Item #B234 Comparator set to measure what that ends up being as a BTO measurement. Once you have that measurement, Load up a seating depth ladder close to what that measurement is, for instance if it measures 2.610 BTO, i would load a ladder 3 rounds at each depth from 2.619 down to 2.601 in 3 thou increments & go shoot them, Giving you a 18 thou spread in seating depth around the area that worked for you before. Surely somewhere in there you will find what works.

That makes perfect sense except for the issue of proud primers. Checked yesterday, sure enough, couldn't see with the eye but certainly sufficient at times to cause anomaly.

Originally Posted by RugerM77

That makes perfect sense except for the issue of proud primers. Checked yesterday, sure enough, couldn't see with the eye but certainly sufficient at times to cause anomaly.

Who has a primer in an empty case ?


I'm assuming you mean after with loaded rounds ? This problem is easily rectified with a primer hole uniformer tool or whatever it's called.
As long as you are aware of it. ...that said I've never come accross this issue personally, are some brands of brass more prone than others ?

Originally Posted by Micky Duck

understood.....what Im saying is that if you already have a load that shoots well in your rifle..eg in my case factory 130grn old school silver tip in .270

when I set up seating die using that for other spitzer projectiles the difference in olgive shape /how curvey the front bit of projectile is, isnt a huge deal as the ring that contacts..be it 4.5mm or what ever will be same distance from base of case and same distance from start of rifling..so the only difference in rounds over all length or distance to rifling is going to be tiny...that 4.5mm might be at worst 1mm either way on different projectile.... you multi ladder testing types will be reworking load after changing component anyway so point is moot..if your using the SAME projectile that 4.5mm ring will be in the same place....

I hear what you're saying, but I'm getting up to 15 thou varience with corelocts. I understand that it's a mass produced and cheap projectile. Same, but not quite so bad with Sierra's. Perhaps I'm chasing the grail. I have BT and AB loads that I can measure with COAL and get away with it, easily inside MOA every time, but I don't want to waste them. Case in point, 4 coreloct's, at a given meaured load well under MOA, let's try for a five shot group, " No don't, you know what'l happen" Yep 1 1/2" off centre. It wasn't me and not the rifle. Arrogant, yeah, but I've done enough to know.( mods, can we have spell check?) That's the conundrum and how to solve it?

Originally Posted by RugerM77

That makes perfect sense except for the issue of proud primers. Checked yesterday, sure enough, couldn't see with the eye but certainly sufficient at times to cause anomaly.

Personally ive never had issues with proud primers with any of the rifles i load for, but i have heard of people putting their shellholder on the case before measuring BTO to rule out any issue in measurement that a proud primer could give. If your issue is cheap projectiles that have inconsistent OAL or ogives, Then thats a poor quality projectile problem & i dont believe there is going to be a way to get it shooting consistent. May be able to go through and use the comparator to measure each projectile and sort them into batches & then load accordingly for the seperate batches, But to me it seems like its probably more hassle than its worth chasing accuracy from a projectile that is going to be innacurate by design.

It may be worth selling the corelokts to somebody who can use them for their intended use (shooting game at modest ranges) & spend some money on projectiles that are less fussy with seating depth (i find ELDX/ELDM in my tikka rifles to not be overly fussy with seating depth ie big window between what works and what doesnt). Will certainly cost more per shot but is going to save you time , components (especially important in the current powder/primer climate) & headache trying to make projectiles do something they werent designed to do

Originally Posted by 6.5 CRD

Personally ive never had issues with proud primers with any of the rifles i load for, but i have heard of people putting their shellholder on the case before measuring BTO to rule out any issue in measurement that a proud primer could give. If your issue is cheap projectiles that have inconsistent OAL or ogives, Then thats a poor quality projectile problem & i dont believe there is going to be a way to get it shooting consistent. May be able to go through and use the comparator to measure each projectile and sort them into batches & then load accordingly for the seperate batches, But to me it seems like its probably more hassle than its worth chasing accuracy from a projectile that is going to be innacurate by design.

It may be worth selling the corelokts to somebody who can use them for their intended use (shooting game at modest ranges) & spend some money on projectiles that are less fussy with seating depth (i find ELDX/ELDM in my tikka rifles to not be overly fussy with seating depth ie big window between what works and what doesnt). Will certainly cost more per shot but is going to save you time , components (especially important in the current powder/primer climate) & headache trying to make projectiles do something they werent designed to do

Sadly, I think you're quite right. I'll just have to suck the kumara in that regard.

Originally Posted by Micky Duck

understood.....what Im saying is that if you already have a load that shoots well in your rifle..eg in my case factory 130grn old school silver tip in .270

when I set up seating die using that for other spitzer projectiles the difference in olgive shape /how curvey the front bit of projectile is, isnt a huge deal as the ring that contacts..be it 4.5mm or what ever will be same distance from base of case and same distance from start of rifling..so the only difference in rounds over all length or distance to rifling is going to be tiny...that 4.5mm might be at worst 1mm either way on different projectile.... you multi ladder testing types will be reworking load after changing component anyway so point is moot..if your using the SAME projectile that 4.5mm ring will be in the same place....

It’s quite common for rifles to have a CBTO tune window (node) of 0.006” (1.5mm). So using your example above, the 1mm variance either way equates to 0.008” between shortest and longest CBTO for a given projectile. So while you consider it to be tiny, it’s is enough to put you well out of a previously good performing node.

You really need to understand that the slightest difference in shape or profile of the ogive, will give a massive difference in CBTO measurement.

Originally Posted by gqhoon

It’s quite common for rifles to have a CBTO tune window (node) of 0.006” (1.5mm). So using your example above, the 1mm variance either way equates to 0.008” between shortest and longest CBTO for a given projectile. So while you consider it to be tiny, it’s is enough to put you well out of a previously good performing node.

You really need to understand that the slightest difference in shape or profile of the ogive, will give a massive difference in CBTO measurement.

That’s 6 thou and a lot smaller than 1.5mm. Most people tune in the 3 - 5 thou window. 0.07mm - 0.12mm

Originally Posted by McNotty

That’s 6 thou and a lot smaller than 1.5mm. Most people tune in the 3 - 5 thou window. 0.07mm - 0.12mm

You’re right, my maths sucks. But the point remains, +/- 1mm difference in seating depth makes a massive difference.

Originally Posted by gqhoon

It’s quite common for rifles to have a CBTO tune window (node) of 0.006” (1.5mm). So using your example above, the 1mm variance either way equates to 0.008” between shortest and longest CBTO for a given projectile. So while you consider it to be tiny, it’s is enough to put you well out of a previously good performing node.

You really need to understand that the slightest difference in shape or profile of the ogive, will give a massive difference in CBTO measurement.

if the projectiles are not the same at that given point on curve of tip...they wont be the same at fattest point either..so point is moot.. either they are the same projectiles with same shaped jacket or they are not..agree the cartridge overall length will vary because of tip shape..but he point the seater pushes..for want of better word,should be the same for all your projectiles in that batch,it will be same fatness,so no different than seating from your olgive point.... the fattest part closest to the tip.

Originally Posted by Micky Duck

if the projectiles are not the same at that given point on curve of tip...they wont be the same at fattest point either..so point is moot.. either they are the same projectiles with same shaped jacket or they are not..agree the cartridge overall length will vary because of tip shape..but he point the seater pushes..for want of better word,should be the same for all your projectiles in that batch,it will be same fatness,so no different than seating from your olgive point.... the fattest part closest to the tip.

It’s not a moot point. The tip to ogive variance is exactly what you need to be aware of when seating projectiles, as any variance in ogive shape will absolutely give different case base to ogive dimension and therefore different jump to the lands.

That is one of the reasons that people modify seating stems to better match the ogive shape of their favourite VLD projectile. The point of contact is then over a longer length of the ogive radius, which is likely to be more consistent over the longer length than just a single, thin point of contact of a standard stem.

any varience in olgive shape..is a varience in PROJECTILE shape so will change your inflight characteristics by similar amounts to a change in seating depth..which brings up next point...if your projectiles are slightly different shape and you are seating them so they are all the same via the point on curve etc the depth inside the case will vary..your pressure will vary your velocity will vary so your shooting yourself in the other foot trying to save the first foot from being hit. but below 150 yards it wont matter a monkeys arsehole anyway if your rifle is even half decent.
your focus on jump to lands =not focus on depth inside case no matter what you do if your projectiles arent all the same you will HAVE to end up with a varience somewhere. turned necks should in theory ensure all projectiles are pushed into case the same Vs seater possibly squishing into curvy side a tiny bit so slightly less deeply seated..but most folks dont bother anymore with neck turning....
sure as heck dont for hunting ammunition.
modified stems for VLD came about as many seating stems werent enguaging SIDE of projectile at all as the needle like tip on VLD was bottoming out before it could... the same issue from opposite angle as I strike with 170grn round nose in .270... I need to back the die itself out of press as the seating stem cant lift high enough to work. they hit the inside of seating stem right at blunt tip so something like 1/4" closer to base of projectile to normal.

Its not shooting yourself in the other foot at all. Its being aware of the factors which affect harmonics and ballistics and then managing their effects for nett benefit.

And I don't focus on jump at all. I focus on consistency of jump (ergo, seating depth), irrespective of how much jump it is. I'll happily run anywhere from 0.050 - 0.080" of jump in my match rifle, because I know they're all within 0.001" of each other and that is what matters. And loading 100 rounds to within 0.001" doesn't require me to seat long, to measure and then incrementally seat deeper until they're all the same either. I can achieve that outcome by understanding what the important variables are and managing them through my loading process.

And that doesn't mean internal case capacity and pressure is being ignored. It is simply understood what affect it can have on ballistics.

Your understanding of neck-turning is woeful. No-one turns necks in order to manage seating depths, or concentricity.

VLD stems came about because the tip of VLD projectiles touch the inside top of a standard seating stem. But people modify VLD seating stems to 'match' their VLD projectile to give a longer contact surface. Go and drill out the inside of a standard seating stem so the tip doesn't touch and you'll see that it has no improvement on contact area with the projectile and so still have variance in seating depths.

your reading skills are woeful.....
you cant have it both ways...yo usay you have consistant jump to lands..... measured from the first fattest point on projectile??? correct so far????
so ALL your projectiles have eggzachary the same amount of distance from that fattest part of projectile to the start of rifling....with me so far???
but then yo usay yo ucant achieve that by seating all your projectiles from a certain fatness of projectile a certain point down the curve of projectile eg the ring the seating die contacts..... and yo usay thats inconsistant as projectiles are all slightly different..SO IF projectiles are all slightly different and you are seating them to make that fattest point..for want of better term the exact same distance from the start of rifling you are IGNORING the distance from bum of projectile to the primer..you cant have both,physically impossible....and you missed my point on neck turning so will say it again..if you have a fat tight neck and a skinny not so tight neck,your pushing ring wont dent the projectile as much with less tension..it will be a micro millimetre difference but a difference it will be..some of the reload photos shown on this forum have some serious dents around that ring.

I wont be drilling out anything..or using VLD projectiles either..for my kind of hunting shooting its pointless..as indeed are my projectiles,pointless that is.