Using Ballistics Tables For a Garand


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pccraig
December 24, 2007, 11:12 AM
I understand the concept of trial & error when it comes to establishing repeatable performance with a specific load on a specific rifle. Assuming of course all reloading components and conditions are consistent.

Iíve been told that many shooters develop one load for 200 / 300 and another for 600. My goal (if itís possible) is to develop a load for my Garand that I can use ďacross the courseĒ making elevation adjustments only.

So, if Iím using the Remington centerfire ballistics table for example, and Iím able to match the muzzle velocity with the bullet weight and type listed on the chart, can I expect to be in the ballpark with respect to the trajectory figures published on the table ? And therefore, know my required elevation adjustment ahead of time ?

Iím also concerned with the load tolerances associated with the M1 Garand, specifically with respect to damaging the op rod with the incorrect load.

Any feedback would be appreciated.

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Ol` Joe
December 24, 2007, 12:11 PM
Use H4895 as a powder, I have been told it was developed for the military to use in the Garand, and download a ballistic program to find your bullets trajectory. Keep in mind the computer drop tables will only be a estimate and you will have to shoot the load at the various ranges to verify they are correct.
Here are a bunch of free shooting related programs. I personally like "Point Blank" but the others likely will do.
http://stevespages.com/page8b.htm

ocabj
December 24, 2007, 01:59 PM
The different 200/300 and 600 loads usually apply to AR shooters, since the 600 loads for the AR more often than not use bullets that cannot be seated to magazine length.

M1 and M14 shooters usually use the same ammo at all lines.

As far as using a ballistic table such as JBM (http://www.eskimo.com/~jbm/calculations/traj/traj.html), it can be very close, assuming you get all the data correct (bullet weight, BC, MV, elevation with respect to sea level, sight height, etc).

But this also assumes you'll be using center hold (POA = POI) and that your sight picture will be exactly the same at all lines. More often than not, the trajectory table that you calculate won't correspond to the actual elevation adjustments you'll make in real life. This has a lot to do not only with your sight picture differential at the various distances, but also with your sight picture and head/cheek positioning in the various positions (standing, sitting, prone).

Are you asking this because you don't have zeros and are going to shoot in a match? If so, just use the 2-3-11 rule and go shoot. 2MOA from your 100 yard zero to 200, 3 MOA from your 300 yard zero, and 11 MOA from your 300 yard zero to 600. That will get you on paper. Assuming you're shooting in an NRA HP match with sighters, then you'll be able to iron out a zero fairly quickly. If anything, use the match to develop your zeros.

pccraig
December 24, 2007, 02:09 PM
ocabj

OK, just so I understand this, for my Garand, after I have my 100yd zero:

Move 2 clicks up at the 200

Then 3 more clicks at the 300

Then 11 more clicks at the 600

So 16 clicks from my 100yd zero to my 600yd dope, correct ?

Cowboy2
December 24, 2007, 02:09 PM
H4895 and IMR4895 will both work fine. The Hornady manual has a specific section on loading for the M1. Some people develope different loads for different ranges, but I think its usually one for under 500yds, and one for over. 168 and 175SMKs seem to run well in most garands.

Here is a free online ballistic calculator. Its numbers aren't gospel, but they'll be reasonably close.
http://www.eskimo.com/~jbm/calculations/calculations.html

If you want a few websites where garand loads and concerns are discussed in-depth, drop me a PM.

ocabj
December 24, 2007, 05:00 PM
pccraig:

Assuming your sight is 1 MOA per click, then you will use 2 clicks from 100 yard zero to 200. This will get you in the black and you can adjust if necessary.

When you move from 200 to 300, then just come up 3 MOA from your established 200 yard zero. This should get you pretty close and definitely in the black.

When you move from 300 to 600, then just come up 11 MOA from your established 300 yard zero. Again, this should get you pretty close and definitely in the black.

Note: This isn't necessarily the same as coming up 16 MOA from your 100 yard zero to 600. Since if you follow the steps above, you'll actually be doing minor corrections as you move back from line to line.

Also, the 2-3-11 rule applies to all cartridges in Across the Course, .223, .308, .30-06, 6XTC, 6mmBR, .243, etc. The 2-3-11 rule is a method by which you can sight in a rifle quickly during an Across the Course match.

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