Thread: Using comparator tool when seating projectiles.

I just lube the bullets with a tiny amount of fine oil. And don't get concerned about contamination. It just get burnt.

[QUOTE=McNotty;1452736..
Pretty amazing the difference sometimes just by moving a projectile 3-5 thou, can quite often shrink from acceptable to tack driver.[/QUOTE]

Demonstrated that on the weekend. A 5 thou shift changed a "good" load in my target rifle into a hammer. 51 of the 60 shots were Xs ( ~1/2min) at 300m. It was only that the group opened up a bit with fouling after 40 shots that there weren't more.

I bought a tub off alibaba. I think it's about a 300year supply

I fiddle with the micrometer seater till the CBTO is what I want then leave it there and load al my rounds. Fortunately I only use one cartridge so can just leave it there. I measure the loaded CBTO with achornady comparator body and bullet insert. A hex nut ith holes the size of bullets was a bit unstable and wobbly.

If I change the micrometer setting say for a different bullet I write it down then can dial it back to where it was and its pretty good. Its a Redding micro seater I use and you can re zero the dial so mine is set to a

I havent been able to accurately measure my distance to lands so am not worried about getting a particular CBTO, get it the same each time. My lands seem to be > 0.100” further out than the max length I can fit in mag and eject through the action if unfired. So I might not be fussy enough for your purposes.

Handy facts Ive found with my system (7mm NBT 140gr):
The OAL to tip is actually very consisyent ie +/ - 0.002” so my bullets are consistent from “ogive” to tip.
Compressed powder loads result in the bullet being pushed back out a few thou so would be hard to get consistent seating
I apply Imperial dry neck lube inside the case neck sing a brush on a stand tool I got from Reloading direct ( for severa years just screwed an old nylon brush into a bit of wood fixed inside a plastic jar to hold all the black lube tidy. I dont use the white silica powder libe as i think silica is very hard but graphite is softe. My fingers get black ue to case lube and neck lube.

If you're interested in doing it, very accurately, look at the Alex Wheeler method.
https://www.wheeleraccuracy.com/videos
Look at his video "Finding your lands".

Anyone else who has published this method stole it from Alex.

It's useful to establish your contact distance with the lands when the barrel is new and then to monitor the wear advancement over a period of time.

With compressed loads my arbor press struggles.
Sometimes you can stop or minimise jack out (not jack off) by keeping the press handle down for an extended period.

The Sinclair Hex nuts are hopeless.

Another method to secured consistent seating depths and neck tension is to run the sized cases through a mandrel before seating. Remove the sizing button from the fl die so it only size the neck with the up stroke. It's another step but does help with consistency.

Originally Posted by DBD

..Remove the sizing button from the fl die so it only size the neck with the up stroke. It's another step but does help with consistency.

ie, down stroke of the handle

I'm hoping a Forster coax will cure my inconsistent seating depth issues

Each bullet is microscopically different and you just have to accept that the comparator tool isn't as consistant as the seating die. Just set up your first couple to make sure you're where you wanna be off the lands and then run all 50 or so to that setting on your comp seater die. I don't faff with the number variation on the hornady tool. No point.

If you're interested in doing it, very accurately, look at the Alex Wheeler method.
https://www.wheeleraccuracy.com/videos
Look at his video "Finding your lands".

Anyone else who has published this method stole it from Alex.

It's useful to establish your contact distance with the lands when the barrel is new and then to monitor the wear advancement over a period of time.

Well that was bloody interesting. Had to remove extractor off bolt, which was a bit of a pain using rod to extract. Dies set up correctly now. I've been using the jam method, Cortana's, to find lands. Bloody miles out, even backed off 20 thou and more still well into the lands. I think someone mentioned a rabbit hole, I need a torch.

Originally Posted by RugerM77

Firstly I've trawled through this forum back to '12 looking for a definitive answer, might be there but couldn't find it. Hence the question.
I load for two rifles, a .308 and a 7x57. Both quite capable of MOA with specific loads, but not always. I have a resonable understanding of the variables involved but at the moment I'm trying to get my projectile seating sorted. making the COAL as a measurement very unreliable.
I understand the comparator doesn't sit on the ogive but it will sit at the same place for every projectile of same type.



Cheers RM77

right so what youve written here...the last line is WHY if you have a load that works well..so you want to duplicate it...set your bullet seater die up using that round...for the same reason..the seater die will set from SIMILAR place on all SIMILAR projectiles and projectiles of same type SHOULD all end up with that certain point of olgive the same depth as all the rest reguardless of projectile overall length.....and if you want to see huge overall length difference,measure some sierra hpbt projectiles and they still shoot good

Originally Posted by RugerM77

Well that was bloody interesting. Had to remove extractor off bolt, which was a bit of a pain using rod to extract. Dies set up correctly now. I've been using the jam method, Cortana's, to find lands. Bloody miles out, even backed off 20 thou and more still well into the lands. I think someone mentioned a rabbit hole, I need a torch.

Cortina’s method doesn’t find the lands, it finds jam. Depending on leade-angle and lands / groove dimensions, jam is anywhere from 20-25 thousandths into the lands (so past touch point). That’s why he says to find jam and then deduct 20 thousandths for your longest seating depth, only going shorter from there.

Wheeler method is to find the touch-point of the lands.

Firstly @Micky Duck been trying to figure out how to put a post I'm replying in a bubble in italics. I'm missing something, can you assist? Secondly I get Cortina's jam method, been using it, what's interesting though is, even with 20 thou backed off, the projectile is still well within the lands. Yeah, I should just be satisfied with minute of angle with a given load, trouble is it doesn't always and I'll be arrogant and say it isn't me. That's why I'm fng around. The bonus is my limited knowledge slowly becomes less limited.

I just quoted you..and deleted the bits not relevant to what I trying to say...

hopefully you got what I meant???