Author Topic: Help finding my OAL  (Read 299 times)

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Offline schnellschnell

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Help finding my OAL
« on: January 14, 2018, 07:31:07 PM »
OK, I'm new to reloading but have read / watched / reread / played around and am feeling ready to start making some actual rounds. I read the pinned posts a few times, and am asking about my Shadow2's OAL. I tested with my Campro plated 124gr RN bullets in my WIN brass and recorded a MAX of 1.148" and MIN of 1.144" as my OAL, with an average of 1.146".

First question. Initially I averaged it out, but then wondered if using the min number is a better place to start? What should I start with? (I used a few different bullets from the box to come up with my measurements). Or for the difference being 0.002 do I just round to the nearest 0.005"?

Secondly. Published data from Campro has an OAL of 1.120" so even after subtracting .015" from my measurements I should be well within safety using their published data. Would I then stick with -0.015" shorter than my OAL if I can keep it close in my press?

INFO:
Shadow2
WIN brass, once fired by me
CCI Primers
550C press
Dillon dies
Campro bullets - http://campro.ca/images/9MM124.pdf
Power Pistol powder (Campro sent me data for it)


Thanks,

J

Offline pewpew4life

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Re: Help finding my OAL
« Reply #1 on: January 14, 2018, 07:36:57 PM »
If you want to know the OAL you should be loading to you need to do a plunk test. Have you done a plunk test yet?

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Offline schnellschnell

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Re: Help finding my OAL
« Reply #2 on: January 14, 2018, 07:39:26 PM »
pewpewlife, I am measuring OAL from Wobbly's post: http://www.czfirearms.us/index.php?topic=34225.0

Is there another way? Once I make the first few at that OAL I will of course plunk it and see. Am I missing something?


j

Offline Wobbly

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Re: Help finding my OAL
« Reply #3 on: January 14, 2018, 08:08:44 PM »
OK, I'm new to reloading but have read / watched / reread / played around and am feeling ready to start making some actual rounds. I read the pinned posts a few times, and am asking about my Shadow2's OAL. I tested with my Campro plated 124gr RN bullets in my WIN brass and recorded a MAX of 1.148" and MIN of 1.144" as my OAL, with an average of 1.146".

First question. Initially I averaged it out, but then wondered if using the min number is a better place to start? What should I start with? (I used a few different bullets from the box to come up with my measurements). Or for the difference being 0.002 do I just round to the nearest 0.005"?

Secondly. Published data from Campro has an OAL of 1.120" so even after subtracting .015" from my measurements I should be well within safety using their published data. Would I then stick with -0.015" shorter than my OAL if I can keep it close in my press?

INFO:
Shadow2
WIN brass, once fired by me
CCI Primers
550C press
Dillon dies
Campro bullets - http://campro.ca/images/9MM124.pdf
Power Pistol powder (Campro sent me data for it)


► First of all... Welcome Aboard !

► You're doing just great, and you've asked some great questions. On your pushed OAL findings.... 0.002" is smaller than a human hair so we really can't get too carried away. First of all it's small. Secondly, your production OAL will vary by 0.005 to 0.008" for the first few hundred rounds. Novice reloaders just do. Thirdly, the 0.015" we're going to subtract will cover a host of errors, this being one of them. So we'll work with ~1.145" becasue it makes the math really easy ! So your Max OAL becomes 1.145 - 0.015, or 1.130" with THAT bullet in THAT barrel.

► Secondly, realize that the published data is NOT a recommendation; it's merely a lab report. And the report says, this is what we did and no one got killed. If you stay close to this you won't die either. But realize we can only stay "close" becasue we'll never have an exactly matching list of components. But luckily close is good enough, becasue we're going to begin our loads at the "Starting Load".

Here's a cartoon to explain the next part...


You can load at any OAL you want between what the barrel allows (the Max OAL found by the "push test") and the Load Data, which becomes the Min OAL. So in your case you're allowed to load anywhere between 1.130 (max) and 1.120 (min). Often times this range may be a whopping 0.100", but today with this bullet/barrel combo it's only 0.010".

► At this point another situation comes up, which is seating depth, or the amount of bullet pushed into the case. We've found that there needs to be at least 0.200" inserted, and hopefully something closer to 0.250" in order to get good accuracy. However, some cases won't let you go much past 0.250", so don't get carried away. More is NOT better.

To make this calculation you need to know the length of the bullet, a number we don't have, but you're a smart guy and can work that out. But which OAL gets you closer to 0.250" insertion, becasue that's highly desirable.


Other Tidbits
• Your 550 is going to produce OALs with lower variation when used with all the shellholder slots full.
• A little case lube (like Hornady One Shot) is really going to help you maintain OALs too.
• Your Dillon dies have an internal seating anvil that can be flipped around or changed. Choose the anvil that fits the bullet the best. You really want zero side-to-side movement so that the bullet is centered up during seating. It's REALLY important the axis of the bullet be on the axis of the cartridge.


Hope this helps.  ;)
« Last Edit: January 17, 2018, 02:00:50 PM by Wobbly »
In God we trust; On 'starting load' we rely.

Immature reloaders ask: What's wrong with this gun?
Mature reloaders ask: What did I do wrong ?

Offline pewpew4life

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Re: Help finding my OAL
« Reply #4 on: January 14, 2018, 08:40:45 PM »
pewpewlife, I am measuring OAL from Wobbly's post: http://www.czfirearms.us/index.php?topic=34225.0

Is there another way? Once I make the first few at that OAL I will of course plunk it and see. Am I missing something?


j
Sorry, I was just waking up when I read your post. I wrote plunk test, but meant push test. My bad.

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Offline schnellschnell

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Re: Help finding my OAL
« Reply #5 on: January 14, 2018, 11:05:34 PM »
Thanks everyone. Wobbly, the bullets are .570" so with a resized case of 0.750", if I do OAL of 1.120" I'll only have 0.200" inserted.

Bullet (0.570) - [OAL (1.120) - Case (0.750)] = 0.200   :right?

So I'm living with that I guess then. Should I be looking for different dimension bullets? I have 1000 of these!


j

Online IDescribe

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Re: Help finding my OAL
« Reply #6 on: January 15, 2018, 02:36:14 PM »
Bullet (0.570) - [OAL (1.120) - Case (0.750)] = 0.200   :right?

Or Bullet [(0.570) + Case (0.750)] - OAL (1.120) = 0.200  ;)   Either way.  ;)


.200 is fine.  You're fine.

Offline Wobbly

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Re: Help finding my OAL
« Reply #7 on: January 16, 2018, 11:53:32 PM »
You're fine.


+1.
Agreed. Always use these bullets at OAL 1.120".

 ;)
In God we trust; On 'starting load' we rely.

Immature reloaders ask: What's wrong with this gun?
Mature reloaders ask: What did I do wrong ?

 

anything