Thread: A couple of new toys comp seating die and Comparator for Measuring sholder bump etc

Hay guys picked up a couple of bits of kit for my new rifle
And haven’t got any experience with how to use them
The 1st is a redding competition seating die
The instructions are a little vague I have got it set correctly in the press that was easy but im haveing troubble
With seating depth adjustments from reading the instructions you get it close with the alan key adjustment in the top while holding the micro Meter on zero? Then do fine adjustment will have the Micrometer ?
But when usesing the micrometer im getting anywhere from 1-5 thou of adjustment per 1 thou mark🧐
So im doing something wrong??

Second is the hornady Comparator set when useing to messure Cartridge bass to ojive
It’s giving me strange measurements like 3 or 4 different measurements for the same cartridge

If i messure coal they are the same within reson

Can anyone in lighten me where ive fucked up 😂

Digital verniers with a battery going flat?

It's a feel thing. Neck tention can vary. And the way you work the press, if your too fast especially on a case with not so much neck tention you can over shoot the mark.
Pretty much the same with the headspace gauge. Also your calipers take a bit of feel to be consistent. The set up when your zero takes the same feel. From memory the attachment is suppose to be on the fixed side of the calipers I think, there is a reason. I haven't used mine for a while.
Also if your not already.... Before you take a final reading turn the case a bit in the gauge/calipers to basicly settle it square. Another possibility of a fired case is the head or shoulder isn't square reflecting the chamber or some condition of the case being fired.
But really this is all just the nature of the beast, you just find ways to get better or deal with it.

Could this be just the variation in the ogive of the bullets - specifically in the distances between the tips and where the seating stem makes contact? Easily checked I suppose by seating the same bullet progressively deeper by some increment - maybe 0.005" each time - and checking that the CoL does reduce by this amount?

[QUOTE=the hornady Comparator set when useing to messure Cartridge bass to ojive
It’s giving me strange measurements like 3 or 4 different measurements for the same cartridge

If i messure coal they are the same within reson

Can anyone in lighten me where ive fucked up 😂[/QUOTE]

A couple of things I've found along the way.

Close the jaws down to your zero point and hold up to a light source to see if they a clamping down square onto the comparator e.g. no light between top jaw and comp head.

when assembling on to the calipers have all locking screws loose and tighten down while holding the jaws lightly closed at the zero point.

The other thing to check is that your primers are not sticking up proud of the cartridge base.

Hi Rambo, I use the same two pieces of kit and I get the CBTO reading within .002" . The micrometer seater seems good but I'm moving in jumps of .005" at a time. M
Remeasurung the same case several times gives readings within .001". Measuring case base to bullets tip does vary a but up to .005" sometimes due to the plastic tips varying a bit I guess.

Looking at opportunities for improvement: try rememeasuring something several times like a case length . Should be the same each time to + or - 0.001" . If not theres a problem with your feel or the micrometer or dirt/ grit somewhere.
I gently rotate the case in the caliper when using either bullet ogive or shoulder gauges. It often settles in. Usually the case base isn't sitting completely flat and square on the caliper when I first put it in place.
I use a little red "anvil" attachment that the case base sits on on the caliper. Stupidly expensive for what it is.
A final problem I've had is with compressed powder loads where the press springs a little and the bullet isn't seated to the same depth as when there's less powder in the case and it's not obstructing the bullet being seated right in. This can be up to. 020" in my limited experience
could be a press problem out of line springy or something.
Some people size their brass then rotate it in the sizing die and resize. This is in case the base isn't square due to crooked chamber or perhaps die. That could give crazy different measurements each time you do it.
I use a forster coax press which has the die mobile so it can center itself on the case which some people say is better for concentricity and stuff.

I think they are both good pieces of equipment and highly recommend.

That hornady body thing can take either an insert to measure to the bullet ogive ( better than a multi hole nut thing I used before ) . The hole is the same nominal diameter as you bulletcalibre.




or else you can put in an insert to measure where the shoulder is which has a hole about .350" or .400" depending on the case you're using.

Originally Posted by Bagheera

That hornady body thing can take either an insert to measure to the bullet ogive ( better than a multi hole nut thing I used before ) . The hole is the same nominal diameter as you bulletcalibre.



or else you can put in an insert to measure where the shoulder is which has a hole about .350" or .400" depending on the case you're using.

Yep have both and will be sholder bumping rather than fls for this rifle (6.5 creedmoor)

It could well just be shit Calipers there only a $20set
Never had problem before but might be time for an upgrade and buy a nice/expensive set

Have you got something of a known length that you can measure 10 times with your calipers?

I wondered if my calipers were throwing an error but before I checked them out I got an engineer mate to turn a 8mm rod to an exact length (2.800") which was checked on his fancy machine. My calipers were measuring exactly 2.800". So that saved me however many dollars and I went elsewhere to look for the problem.

However maybe you just want a new pair of calipers anyway!

If I can find that piece of rod I can mail it to you if you like. Should probably try and find it first before I offer stuff...

I have a $30 set of dial calipers from EbayUK. I have compared them against multiple $300+ digital sets at work and mine are spot on (if the amount of pressure/feel applied is consistent and correct).

I have got a pretty good feel for them and I can now get consistent accurate results (within 0.0005”) on the same cartridge for ojive and headspace measurements. From case to case all my cases seem to come out within +\-0.001” of my target measurement just using standard RCBS dies. The comparator set for both headspace and ojive bushings seems to have 0.003-0.004” of flex that I have to take up before getting my true measurement. However, once I got that feel for the flex right, I’m pretty happy and really consistent.

I can’t speak of micrometer seating dies as I have never used them, but that does seem weird to jump 0.005” with a 0.001” adjustment, as it’s merely a linear thread. The standard RCBS seating stem is 0.032” per turn so I just work out how much adjustment I need (e.g approx 1/2 for 0.015”).

So ive replaced the batteries which made a difference
Had a play with it all
Best I can get it within 0.004 of each other useing the same round measurements from the ojive with the hornady thingy

5 measurements
2.270
2.274
2.274
2.273
2.270
Probably close enough I Geuss

I have the same gear and I definitely get variation between rounds even after the seating depth is all locked off. I can’t remember off the top of my head but I think the variation would be similar to yours above. I have always just figured that with such tiny measurements there must be so many minute variations such as bullet ogive position, spring back when seating, friction between projectile and case neck, that some variation in measurement is inevitable. The next thing to do is shoot them I guess and see how accurate they are!

The comparator... gotta use it without primers, once the cartridge is in the device tighten down with the calipers and give the brass a little spin to help seat it square, eyeball it too to be sure it looks square. And that's the best you can do. That error range is not unlike what I'd get. Some of it is due to inadequacy in the measuring system and some of it will be variation in the brass. If you resize the 2.274s again you might get a little closer to 2.270.

With all the advice given ^^^^, I might just go back and check a few CBTO measurements.
As an aside, I usually neck size with a Lee collet die, 308W, and rotate the case to at least 3 positions, before going on.
Also do the same when seating the bullet (Hornady Micrometer seater - not VLD though), and find that the CBTO measurement stabilized to within 0.001" - more than sufficient for my feeble attempts at LR range efforts.
Haven't checked case/bullet runout on a jig, but no visible movement by eye, when rolling along a bench.