7mm rem mag question
- Thread starter Sheephuntr
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Herringbone
Active Member
I don't see anything concerning from the pics??? I run 68.5g of RL26 with 168 VLDs and have no problems with pressure.
Sheephuntr
Well-Known Member
I was at 68 an had two heads separated. I backed it down to the lower node I found an it's still making the funny marks. I did change brass to from Hornady to winchester
Like Herringbone, I run 68.5 grains of RL 26 with168 Bergers 215 match primers and Norma brass. No problems and 3085 fps velocity. I have only had one case head separation in 45 years of reloading and it was a Winchester case.( 375 H&H and hot load of WW760 30 yr ago and I probably over-bumped the neck of the reload not knowing any better). I always try to use Lapua or Norma brass. Peterson and ADG seem to get great reviews but I don't have any experience with them. Your photos don't show anything out of the ordinary except maybe your chamber isn't highly polished.
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Herringbone
Active Member
If you are blowing case heads at 68gr I would double check the headspace before I shot anymore.
Sheephuntr
Well-Known Member
How do I go about checking headspace? What I am seeing on the cases in the picture is exactly what I'm seeing on the 68grain load
Keith1
Well-Known Member
If you are having case head separations with a belted case you are probably sizing the brass to much. Back off a little on your sizing die. Case head separation is NOT a to much powder indication.
Bob Wright
Well-Known Member
If your not up to speed on headspace, don't shoot any reloads in this lot you may currently have.
Go borrow or buy a headspace comparator. Hornady makes one, there are others.
Attach this to your caliper and measure fully fire-formed brass according to
directions. Then measure brass you have full length sized.
Ideally, you should only bump the shoulders back in your brass by .002-.003. Make sure you use the correct number bushing for the 7mm Remington mag chamber you have.
Ton of info online for this.
All your other empty brass you have full length sized, or if loaded, should probably be unloaded.
Use a straightened paper clip to feel for a groove forming near the head where they are separating on the others.
You don't have a pressure issue if case heads are separating due to over bumping the shoulders.
When you have case head separation its because the case has stretched in the same place too many times. This is almost always because the shoulder is sized way to far back leaving more head space then when you fire it again, it stretches again in the same place(it doesn't stretch at the shoulder).... eventually you have case head separation. Sometimes it doesn't take but just a few firings for it to happen.
MOOSE39465
Well-Known Member
Take the plunger out of your bolt and keep sizing it in very small increments until your bolt closes with very little resistance at the end of bolt cycle.
Your still guessing doing it this way takes a very small amount of screwing the die down to make .002-.003.
Take the advice above buy a comparator.
Creedmoor shooter
Well-Known Member
Your oversizing your cases. Case head separation is not a over pressure sign. Do yourself a favor and get a comparator to measure your shoulder bump.
codyadams
Well-Known Member
You can have case head separations running 20,000 psi, has very very little to do with pressure. It's sizing, as others have said. Get a good reloading manual and read up on setting your die for proper head space, it will make a world of difference, especially with a belted case.
bigbull
Well-Known Member
+1
Deffinetly not a case problem, method of loading issue.
Adjust sizing to suit chamber dimensions, do not over work the cases.
bb
