Any opinions or theory’s welcome

[smithp18]

Hi
Loaded up 130gr -150 gr (Nosler) for my .270 with the cases fully re-sized and trimmed to exactly the same length. (Federal)
When seating the bullets using a comparator on verniers I was getting a difference on the OAL.
The target OAL was 2.8100, I was finding that I was getting most of them bang on but every now and again I would get a OAL 2.8050 or 2.8150.
I know this might seem a little anal but it annoys me.
I use RCBS shell holder, Press and Dies, I have checked the press for ware on the leverage system but seems ok the shell holder seems fine to
The only thing I was wondering has anybody found issues with inconsistent ogive diameters or profile re Nosler heads, it’s the only thing I can think of at the moment but it’s difficult to measure.

Any opinions or theory’s welcome

Smithy

 

[finnbear270]

Sounds like a vernier slippage!, for such a small amount.

 

[csl]

I've only been reloading a year or so but here are my thoughts...

Is the resolution of your calipers 5 thou? it might seem like you have odd ones at 5 thou either side but you'll find that the ones you believe were bang on at 2.8100 could have been anywhere between 2.8051 and 2.8149 so you probably have a +/- 5 thou variation across them all with the majority in a +/- 2 thou bracket. I don't think that's too bad. For reference I probably get a +/- 2 thou variation using .30 cal speer soft points (my calipers go to half a thou)

As for why that's happening...

Bullet variation, as you say
Bullet not quite seating right in die - e.g. does bullet always comes to rest on the ogive and not slightly on the tip?
Slight variation in neck tension on the cases, causing a minute amount of spring back?

those are the only logical things I can think of at the moment.

Alex

 

[Weather Witch]

Thanks very much Alex & Finnbear270, interesting stuff this reloading.
Just out of interest what type of calliper do you use?

ATB

Smithy on other halfs login!

 

[csl]

Edit: oops I misread -thought you said which calibre!

My calipers are Mitutoyo

Alex

 

[smithp18]

That's a relief Alex, am on same as you!

Cheers

 

[nell]

Smithp, i use the same set up as you are and have done for many years, have you tried rotating the bullet in the comparator?

If so i'm sure that if your measuring to .5 of a thou you will find quite a variation on one rotation (i use mainly Honady in several calibre's)

AS mentioned that A word crops up regularly when reloading...


Nell

 

[jcampbellsmith]

I've only been reloading a year or so but here are my thoughts...

Is the resolution of your calipers 5 thou? it might seem like you have odd ones at 5 thou either side but you'll find that the ones you believe were bang on at 2.8100 could have been anywhere between 2.8051 and 2.8149 so you probably have a +/- 5 thou variation across them all with the majority in a +/- 2 thou bracket. I don't think that's too bad. For reference I probably get a +/- 2 thou variation using .30 cal speer soft points (my calipers go to half a thou)

As for why that's happening...

Bullet variation, as you say
Bullet not quite seating right in die - e.g. does bullet always comes to rest on the ogive and not slightly on the tip?
************Slight variation in neck tension on the cases, causing a minute amount of spring back? ************

those are the only logical things I can think of at the moment.

Alex

Alex's point 3 is well worth exploring with a http://www.sinclairintl.com/product/6801/Case-Gauges-Headspace-Tools Try and find someone local who has one.
I get the heads moving +/- 2 thou wrt to my datum OAL. As I have focussed on the necks I have reduced this variation.

Secondly and not very scientifically, I find sometimes seating the bullet is harder and upon measuring the resulting round, find a longer OAL.

 

[Muir]

Smithy,
This is normal with bench mounted equipment and non match bullets. I published a test using a Lee Loader VS the RCBS bench mounted gear and found that the "inline" seater using a mallet to drive the bullet in had closer tolerances in OAL, by half. Don't sweat it.~Muir

 

[jcampbellsmith]

Smithy

A couple of articles worth having a look at:
http://blog.sinclairintl.com/2009/03/26/determining-bullet-seating-depth/
http://search.freefind.com/find.htm...ullet+seating&Find=Search&mode=ALL&search=all
Have fun.

 

[smithp18]

Thanks for the replies, all-learning, what I meant to say Alex was I to use Mitutoyo (absolute) verniers.


smithy

 

[JAYB]

Phil,

I would guess that it is an accumulation of different things, not the least of which would be the variation in the non-machine component involved, with the biggest scope for variation - you . I should imagine that the slight variation in each stage of the process contributes to the difference, and as Muir rightly points out the "bench" method as opposed to the mallet whacking "in line" method does present just such opportunities, as would the variations in mass produced bullets. Having said that +/- 2 thou on the odd round is a very good achievement, so relax your sphincter and go shoot something.

Just one more thing, when you use Michelle's account do you wear her clothes .

John

 

[User00014]

ive found the same thing with my 6.5 again with nosler partition 140gn , i use RCBS calipers and my dies and press ate LEE !
no matter what i try , ive given up worring about it .

they shoot straight with a sub inch group so my theroy is if it works it dont need fixing , my OAL is 3.100" , and some are .oo5" either way , im putting it down to the lead soft points being slightly out !

cheers lee

 

[smithp18]

Thanks John,Lee
Oh John I sometimes try Michelles clothes by request,
But she wears mine all the time!!!

Phil