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Old March 29, 2013, 07:52 PM   #1
trobin
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COAL

I purchased a Hornady OAL Gauge. I used it in a Remington 700 .270 Win. I repeatedly got readings of 2.953" using a 140 Accubond and a Hornady Comparator. I loaded some rounds using those measurement minus .04". The loaded rounds COAL is 3.508".

Any opinions?
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Old March 29, 2013, 08:09 PM   #2
Brian Pfleuger
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The gage is actually measuring the distance from the case shoulder to the bullet ogive. You need to compare the shoulders of your own cases to the shoulder of the modified case.

If your case shoulders are .005 longer than the modified case, you would add that .005 to the measured length to get the length that would touch the rifling in your gun.

THEN subtract the .040 or whatever length you choose.

3.508 seems awfully long considering that it would be .168 longer than SAAMI max but only you can know what you gun measures. If it fits and functions, start at starting loads and work up.
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Old March 29, 2013, 08:15 PM   #3
trobin
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Shouldn't the modified case be the same as a full length resized case?

I've cycled a few rounds through and they cycle fine. No sticking or feed issues.

Last edited by trobin; March 29, 2013 at 08:17 PM. Reason: Add
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Old March 29, 2013, 08:20 PM   #4
Brian Pfleuger
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Quote:
Shouldn't the modified case be the same as a full length resized case?
That depends on how you size your cases. Properly sized cases should be .001-.002 shorter than your chamber.

The modified case is sized by Hornady to SAAMI minimum length.

My sized cases are all slightly longer from base to shoulder than the modified cases.

Take a permanent marker and color the bullet on one of your rounds. Chamber it carefully and extract it. Check if the rifling has scratched off the marker. Even if it does, if you start at minimum and work up, you'll be safe but pressures will be higher than if the bullet wasn't seated in the rifling.
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Old March 29, 2013, 08:27 PM   #5
trobin
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I resized the cases to rcbs instructions.
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Old March 29, 2013, 08:46 PM   #6
Brian Pfleuger
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COAL

Die setup instructions are starting points. You should be sizing the brass so that the shoulder is moved 1-2 thousandths and no more. Otherwise, you risk excessive working of the brass, the cases stretching too much and eventually head separations.
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Old March 30, 2013, 06:15 PM   #7
PA-Joe
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Are you talking about using the bullet comparator with the OAL Gauge?

As noted you are measuring the distance from the case head to the bullet ogive. Did you using the same bullet that you are now reloading? If you got 2.953 and then subtracted 0.04 then your reloads should measure 2.913. If not then your reloads are too long. Key is you have to take the measurements using the same bullet you are using to reload. The bullets may be going into the chamber but are touching the lands or may be getting pushed back by the lands. Chamber one of the reloads and then re-measure it.

Resizing has nothing to do with seating the bullet in the final step. You need to screw the seater stem down until you get the 2.913.

Now if you are talking about the headspace gauge that is a different story.
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Old March 30, 2013, 07:56 PM   #8
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Getting the correct comparison between your finished rounds and the comparator has everything to do with sizing.

The OAL gage is NOT measuring from the head to the ogive. The modified case is pushed into the chamber until its SHOULDER contacts the chamber shoulder.

You then push the bullet forward until it touches the rifling. There are only two fixed points, the case shoulder and the ogive. Unless your cases measure the same distance from the head to the shoulder as the modified case, they will not exactly match the gage reading. Since the gage is sized to SAAMI minimum, your properly sized cases will almost never match the modified case, unless your gun has a SAAMI minimum chamber.

In reference to the OALs mentioned in the OP, he is talking about the ogive reading being 2.953, resulting in a final OAL of 3.508.
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Old March 31, 2013, 03:56 AM   #9
trobin
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Yes. I used the same bullets for the 2. Ill check the head to datum line on the modified case as well as resized case and see if there's any difference before firing. This gun was inherited and from what I understand its a 1960's model. I don't know how true that is. Anyway the rounds I loaded are 140 accubond over IMR 4831.
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Old March 31, 2013, 09:40 AM   #10
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Trobin, measuring OAL, and COAL are different. Brian told you exactly how to determine you oal and with that you can get your COAL.
Here's what I do:
1. Make sure weapon is clear, and then remove bolt.
2. Screw the modified case down on the LNL tool, and insert bullet of preference into case mouth.
3. Carefully extend the LNL tool rod into chamber and slowly push the bullet in until it stops,( if this rifle was properly cleaned then this is the rifling stopping the bullet.) carefully screw set screw down on the LNL rod.
4. Carefully remove tool and bullet from rifle chamber.( sometimes necessary to push cleaning rod down muzzle to push bullet out of rifling)
5. This is your chambered round with bullet touching riflings, so measure with a set of calipers, without Comparator installed and write this measurement down.
6. Install comparator and proper caliber bushing to caliper, and then zeroe the caliper, with the comparator installed, and write this measurement down.
7. These two measurements will be recorded and you can easily compare the numbers with the book, ( as far as COAL) but for these purposes, use the zeroed comparator number.
8. Deduct, (just to start with, adjustments can be made during load developement) .010 from your comparator measurement, this number is where I start my data and build my loads. REMEMBER EVERY BULLET STYLE OR WEIGHT IS DIFFERENT AND STEPS 1 THROUGH 8 MUST BE USED.
9. Now with the bullet seated in modified case, remove Comparator and zero calipers, and measure COAL, (to make sure the bullet never got pushed back into case), and deduct .010 from this reading and see how it measures against book COAL's.
Hope this simpilfies the procedure you take to measure bulet seating measurements, adjust your seating dies accordingly. and relax and have fun.
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Old March 31, 2013, 02:57 PM   #11
trobin
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Hooligan1, that's exactly what I did. I thoroughly read the instructions and watched numerous instructional videos on YouTube. I was surprised with such a long cartridge. I did the same with my 25-06 and ended up with 3.22" COAL using a 110 accubond.
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Old March 31, 2013, 04:14 PM   #12
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That might be the COAL for that 25-06, and that bullet, look at the manual and see what their COAL is for that listed load.
The important thing here is also to make sure there is enough of the bullet seated into the case, start with the dimension of the bullet,(minimum) and move out til you like the repeatability and precision.
don't get discouraged it's fairly easy to get it wrong, and it's easy to correct.
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Old March 31, 2013, 06:32 PM   #13
trobin
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According to my math I have .334 seated into the case mouth. Case was trimmed to 2.532 and oal on bullet is 1.310.
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