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Reloading Forum >
Keyholes w/ 70gr Sierras
Keyholes w/ 70gr Sierras
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JB in MN
1 post
Sep 06, 2004
1:26 PM
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Hiya folks!
Great board here! Been hoping for something like this for a long time.
Here's my problem, if anyone can offer any insight: getting erratic shots resulting in keyholes at 100 yards. Using a rebarrelled and trued Savage single shot action w/ 24" Douglas 1-12 twist barrel. Load is 29gr Benchmark behind a 70 grain Sierra HPBT loaded to 2.1 inches COL, and Lapua brass. I used CCI SR Mag primers in this bunch, btw.
I'm still kinda new-ish to reloading, so maybe I'm doing something wrong. Cases were all prepped, weighed, etc.. Any advice?
Thanks,
JB
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Old Bob
1 post
Sep 06, 2004
5:57 PM
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The velocity may be too fast for that bullet and that twist.
I have similar problem with 20BR, 32 gr. bullets, 10" twist, and lowered the velocity 250 fps and no more tippers.
Old Bob
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JB in MN
2 posts
Sep 06, 2004
7:09 PM
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Thanks Bob, I'll give that a try. You might be right, 29 gr is probably a bit faster than I need anyway.
JB
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ReedG
4 posts
Sep 06, 2004
7:22 PM
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Hi JB:
I've had some excellent groups with 70-gr. Sierra HPBTs in my Savage 12 with 1:14 Shilen barrel. I find that Benchmark is too fast for bullets as heavy as 70-gr. though and have my best groups with Varget. I'm sure the 1:12 will shoot different than my 1:14 but, if you can, try 33.5-gr. Varget with that Sierra. Not sure what length to give you because I seat mine .010" off the lands which is 1.805" to the ogive. If you don't have a Stoney Point gauge or similar, just barely start a bullet into a sized case (no primer) and fully close the bolt on it in your chamber. This is the "jam" length. If you cannot measure off the ogive, carefully measure the OAL. Then load 5 rounds each with the OAL set .005", .010", and .015" shorter than the measurement you got above. I'll bet you will find one of those lengths that will outshoot all the others. Then you can tinker with a couple tenths more and less of powder to see if you can still tighten 'em up a bit. Rule of thumb is that if your groups are spaced horizontal, try a little less powder; if spaced vertical, try a little more. Usually .2 of a grain will show a difference.
Good luck and, above all, enjoy ...
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ReedG
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