Thread: 300 WIN MAG once fired brass chambers no issue

Is this usual?

I have loaded 7RM a bunch, and this never happened, so was wondering if it was particular to 300 WIN MAG, or maybe just this rifle?

What is happening is when I have gone to F/L resize, I check the case against the bolt drop to size as little as possible.

Once fired cases (NOT out of this rifle, so it may just be a larger chamber) have no hesitation dropping the bolt.

A 308 projectile at this point will slide in and out of the case no issue.

Size them and run it, or am I missing something?

Loading Hornady 150grain RN at 3.115" as per the book value, this also seems to be way way off the lands as measured with a lead slug OAL hitting the lands was 3.55ish".

Having not come across this before I thought I had better ask

Maybe excessive head space causing the fired brass to be loose in your rifle what’s the rifle don’t worry about where the lands are

Size them the absolute minimum and run it. If you are full length sizing, set your die so that it only sizes the neck and lad em up.

Next time you laid these cases you may need to adjust the die so that it doesn't over size.

Could have come from a tight chamber.
Check head space by doing the remove primer and putting tape over case base and seeing if bolt will close. You tube will show you how to do it. If all good then do as above and lightly resize. I wouldn't push the shoulder back this time around.

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The brass was probably shot in a tighter chamber than your rifle has. If it chambers so easily with no bolt closing resistance in your rifle now it could be the case that there already is excessive headspace. Yes, size the necks only, as suggested, to get good seating of your projectile but I suggest for a first loading to NOT make full power loads. This may cause case splitting. Better to first shoot the brass with somewhat reduced loads getting them fireformed to your chamber after which you can set a FL die for correct shoulder bump and load em up to full potential if that's your intention.

Thanks everyone

Will they be fully fire formed with a light load? Genuine question

Originally Posted by charliehorse

Will they be fully fire formed with a light load? Genuine question

No, the shoulder often retains a softer radius and the neck and body taper spring back can be nearly 2 thou in places - rather than the usual 1.3 thou

Well, I pulled the necks in, will see how they go tomorrow

The other rifle they came out of was a Tikka, the barrel I have is also a Tikka. I have before measurements and will get after measurements, just for interest.

Unless you're shooting competitively, just load them as above and enjoy shooting them.

Originally Posted by charliehorse

Will they be fully fire formed with a light load? Genuine question

Yes, or very close to, if the reduced load is not too light. At least, that works for me. In regard to new brass I think 7mmsaum is right about springback. I have never actually measured just sometimes found with new brass if takes a couple or three firings to reach the point of getting consistent shoulder bump and a FL die adjusted for the final time. Other times have found new brass perfectly fire formed after one firing so I guess, to me, nothing is set in concrete.