Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Tolerances

  1. #1

    Tolerances

    Hi guys
    New boy on reloading. I was advised to buy another toy - a comparator. I see the OAL using this tool in the calipers gives 8 thou more for factory ammo (Norma 100 gr SP semi pointed) to the ogive than the measurements I took using my Hornady OAL gauge measurements, i.e. 2.204'' vs 1.196'' .
    I am using Nosler partition Spitzer 100 gr in 243.
    I test fired the original measurements and got - 1MOA.
    If factory ammo is meant to have a tolerance of 50 thou and I was working on 20 thou, there seems to be an abnomaly.
    Advice please.
    Last edited by deerpath; 07-04-2014 at 18:53.

  2. #2
    welcome to the world of obsessive measurements!

    The anomoly is that someone recommended you buy a comparator/yet another toy as a "new boy" without making sure you are mastering the basics of case prep, bullet choice, charge choice/measurement and load development

    Most stuff will shoot sub MOA out of the box
    IMO most of the rifle I have fired do not require "land crunching" OAL in order to shoot 1/2-3/4 MOA or below

    I count myself as a "new boy" to this mainly as I refuse to get too excited about micrometers
    loading for 4 cartridges (.222, .243, .270, .300WM) none of the loads I use (53gr, 60gr, 87gr, 100gr, 130gr, 185gr, 200gr, 208gr) are anywhere near the lands and more importantly the distance to or from the lands was not a defining factor in choosing the OAL

  3. #3
    No two measuring devices are going to give you the same answer. If you are going to measure stuff, only measure it with one gauge. Sell the comparator would be my recommendation.

    Regards JCS

  4. #4
    Quote Originally Posted by deerpath View Post
    Hi guys
    New boy on reloading. I was advised to buy another toy - a comparator. I see the OAL using this tool in the calipers gives 8 thou more for factory ammo (Norma 100 gr SP semi pointed) to the ogive than the measurements I took using my Hornady OAL gauge measurements, i.e. 2.204'' vs 1.196'' .
    I am using Nosler partition Spitzer 100 gr in 243.
    I test fired the original measurements and got - 1MOA.
    If factory ammo is meant to have a tolerance of 50 thou and I was working on 20 thou, there seems to be an abnomaly.
    Advice please.
    The combination of comparator (in this case, a thing you attach to your Vernier calipers and which has a nominal bore-diameter hole in it) and Hornady OAL guage can be used to set a particular bullet a specific distance from the lands. The important point is, as i understand it, that you measure the nominal 'distance to the lands' using the OAL guage and the comparator and the specific kind of bullet you're going to use.
    The measurement doesn't translate into anything meaningful with repect to other styles of bullet.

    What do you mean by the word 'tolerance'?

  5. #5
    You are using a "comparator".

    I.e. it is a tool for comparing things. Not an absolutely precise measuring device.

    Used correctly it will let you set up seating depth, jump to lands etc. consistently. But not in any independently measurable manner.

    The Hornady/Stoneypoint tools are just a nominal hole, crudely drilled in a bit of soft aluminium, sold for tuppence h'apenny. They work perfectly well, used within their limitations. They are not necessarily consistent from one to another.

    You also use the fancy word "ogive". As if it is a precisely defined thing. It is not.

    If the point at which your bullet's "ogive" touches the first point in your barrel (maybe throat, or lands, or wherever) at exactly the same point that it touches your comparator, I'd be amazed.

    These crude tools work much better that one would expect, with a sympathetic touch.

    I don't know what you mean when stating "tolerances" of 50/1000" or 20/1000", these are more than ten times worse than what you should be able to achieve consistently.
    Last edited by Sharpie; 07-04-2014 at 21:08. Reason: typo

  6. #6
    You can use the comparator to check seating depths 'round by round' for consistency ensuring the cartridge length measurement taken from a pre-determined position on the bullet ogive to case 'head' is exact to your seating requirement.
    It's better to use this tool measuring from the ogive on a bullet than the very variable length of the 'pointy' bit of bullets to case head.
    However, there's much more to be gained by careful brass preparation well before the bullet seating stage - but as they say, 'every little helps'.

    If only these really were tupenny ha'penny tools Sharpie, in my world they're quite pricey really for what they are. ATB
    Last edited by deeangeo; 07-04-2014 at 21:34.
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Zeiss 8x56, 110gn Nosler Accubond = Game Over!

  7. #7
    Quote Originally Posted by deeangeo View Post
    If only these really were tupenny ha'penny tools Sharpie, in my world they're quite pricey really for what they are. ATB
    So true. They are mis-conceived, an orifice with a slight taper would give a more consistent "kiss" of a typical ogive. And they are crudely made from several pieces of aluminium, which require a certain sensitivity to set up consistently into the calliper jaws. Perhaps hard anodising might improve repeatability/wear. Nevertheless not cheap to buy into the system.

    I now think the hex-nut alternative design is probably rather better. But I have no personal experience with it. I daresay it has it's downsides too.

    In any case, the thing that actually determines seating depth is the seating plug inside the seating die.

    Maybe it will also press on the bullet ogive at exactly the same place as the comparator measurement

    But I doubt it.

    I've done some measurements using a seating plug (the one used in the seating die) instead of a comparator, and unsurprisingly found even more consistent measurements.

    But I doubt that any of this really matters much.
    Last edited by Sharpie; 07-04-2014 at 22:03.

  8. #8
    I pulled the seating plug on my RCBS Comp seating die to check the fit of Nosler 110gn Accubond bullets I use, also Sierra 100gn Prohunters and they seem to fit quite well.
    I agree the Hornady comparator could be rather better than it is, but hey, as long as the same parameter is used each time it'll be good enough for hunting ammunition by a fair margin. I certainly use mine & other tools too.

    I've made my mistakes in the past, but if you have care with sizing die set up for concentricity and headspace, brass prep and seating I reckon it all helps - but the OP looks like he has a way to go before he starts to chase these demons! ATB
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Zeiss 8x56, 110gn Nosler Accubond = Game Over!

  9. #9
    Quote Originally Posted by bewsher500 View Post
    welcome to the world of obsessive measurements!

    The anomoly is that someone recommended you buy a comparator/yet another toy as a "new boy" without making sure you are mastering the basics of case prep, bullet choice, charge choice/measurement and load development

    Most stuff will shoot sub MOA out of the box
    IMO most of the rifle I have fired do not require "land crunching" OAL in order to shoot 1/2-3/4 MOA or below

    I count myself as a "new boy" to this mainly as I refuse to get too excited about micrometers
    loading for 4 cartridges (.222, .243, .270, .300WM) none of the loads I use (53gr, 60gr, 87gr, 100gr, 130gr, 185gr, 200gr, 208gr) are anywhere near the lands and more importantly the distance to or from the lands was not a defining factor in choosing the OAL
    Not an anomaly at all. Shooters are always encouraging newbies to buy 'sophisticated' equipment they don't understand and can't use effectively. ~Muir

  10. #10
    Quote Originally Posted by Muir View Post
    Not an anomaly at all. Shooters are always encouraging newbies to buy 'sophisticated' equipment they don't understand and can't use effectively. ~Muir
    It's all good 'sport' though Muir
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Zeiss 8x56, 110gn Nosler Accubond = Game Over!

Similar Threads

  1. tolerances while reloading?
    By flyingfisherman in forum Ammunition, Reloading & Ballistics
    Replies: 23
    Last Post: 17-05-2011, 19:57

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •