OAL for 300 Win Mag in Ruger M77? - The HuntingPA.com Outdoor Community
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post #1 of 2 (permalink) Old 01-19-2012, 11:21 AM Thread Starter
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OAL for 300 Win Mag in Ruger M77?

Hey- thanks to all for the suggestions in my earlier post on seating depth.

I bought the Hornady Lock & Load OAL gage. Using Nosler Ballistic tips 180 gr Spitzer. Gun is a Ruger M77 300 Win Mag.

The OAL gage requires you to use a pushrod to feel when the bullet hits the rifling, you tighten a lock ring, remove and measure OAL w/caliper.

I did this 15 times- measurements ranged from 3.429 inches to 3.535 inches, average 3.5 inches.

So... the rule of thumb is usually measure OAL and back off 3 thousandths. My issue appears to be the variance in OAL measurement to the rifling is far larger than 3 thousandths. Which one to use? 3 thousandths off the largest, the smallest or the average measurement?

And more specifically- Does anyone reload for the 300 Win Mag for a Ruger M77 using Nosler Ballistic Tip 180gr? If so, what are your typical OALs?

Thanks for any advice.


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post #2 of 2 (permalink) Old 01-19-2012, 11:47 AM
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Re: OAL for 300 Win Mag in Ruger M77?

You need to be very careful with the measurement. I put a wooden dowel in the barrel until it touches the bullet tip (trapping the bullet between the dowel and aluminum push rod), using the dowel and the tool's aluminum push rod you can gently position the bullet repeatedly on and off the lands until by feeling you are sure you have the exact position. I'll do this and measure until I get the same measurement a few times.

Also when you tighten the push rod thumbscrew you need to be sure the rod doesn't move, the bottom of the screw applies a rotational force against the rod and it can move without you knowing it, you have to keep a slight touch on the rod when you tighten the screw, and don't tighten it much or it will move.

You've probably already had the bullet stick in the lands, the dowel ensures the bullet comes out with the tool after the LnL is tightened and removed. Also don't re-use the same bullet over and over too many times as it will engrave with the lands giving a false measurement.

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