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7MM Rem Mag Seating Depth Question

tatasta
Hello All,

I have a Mod 70 Classic S/S 7MM Rem Mag with a BOSS. I really love the gun and have used it for my primary hunting rifle for around 18 years.
I started reloading for it around 5 years ago.

Up til now. I loaded my 7MM rounds to the published COL with very good results. So, no complaints on anything.

Recently, I bought a Hornady Lock and Load Overall Gauge to optimize my seating depth. COL for 7MM is 3.29". I used my Hornady gauge and get a COL of 3.75". Seems like alot of freebore doesn't it? I'm not really sure if that is too much or if it is a problem. Can it be result of troat erosion?

Anyway I loaded some rounds yesterday. I seated them 0.015" off the lands and they fit in my magazine. Should be ok to shoot, correct?

Thank you
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Comments

5 comments

Date Votes
  • 5mmgunguy
    Did you back off the load a few grains? You should and then work up to a new safe level.
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  • sandwarrior
    tatasta,

    The published COL is pretty much a SAAMI standard to "start out with". What you have could be erosion or made slightly longer than Saami. As long as it's not tighter and therefore capable of causing too high of pressure with a standard load. (As in the being too short and the bullets starting out too deep into the lands).

    SAAMI gives a set of measurements for each cartridge. Tolerances by each manufacturer can vary. As long as they don't vary the wrong way and cause standard loads to be high pressure.
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  • tsr1965
    Tatasta,

    Your load should be fine, as long as you are seated off the lands. I would see how it groups, to see if you gained anything, but more space to add more powder.

    I would be suspicious of throat errosion, with that much freebore, but have been experiencing some of the same with a couple Browning A-Bolts. One chambered in 284 Winchester, and one in 300 RUM.

    Good luck and Happy shooting.

    Best
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  • tatasta
    Thanks to all.

    I feel more confident. I will post up accuracy and velocity after the weekend.

    Thanks again!!
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  • skyfish
    Great they fit in your mag. It is a lot but sadly I've seen more. My 270 WSM likes the bullet I use .005" from the lands. We'll see if you get more accuracy.

    One note, reduce slightly on powder and work up. You may find higher pressure with less free bore(I doubt it). Or you may need more powder for more case volume(as I do in my 204 Ruger).
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