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Joined: Jun 2001
Posts: 10,790 Likes: 1
Campfire Outfitter
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OP
Campfire Outfitter
Joined: Jun 2001
Posts: 10,790 Likes: 1 |
I wanted to try seating a 155 lapua scenar to 2.890 and see if it will help accuracy. I originally tested them at 2.755 and got a decent group but wondered if touching the lands would improve it in a tikka ctr? Not sure if it is too far out of case to be safe?
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Joined: Dec 2004
Posts: 14,488
Campfire Outfitter
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Campfire Outfitter
Joined: Dec 2004
Posts: 14,488 |
The only way to know if it will improve accuracy is to try it.
As far as increased pressures go, based on observing velocities in my own experimentation it is my belief that pressures begin to increase when you get to within about 0.010" of the lands. You're pretty far off the lands at this point if you know that 2.890" will be touching lands. Maybe a few rounds at a lowered powder charge would be the smart thing to do.
JMO.
Don't be the darkness.
America will perish while those who should be standing guard are satisfying their lusts.
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Joined: Jun 2001
Posts: 10,790 Likes: 1
Campfire Outfitter
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OP
Campfire Outfitter
Joined: Jun 2001
Posts: 10,790 Likes: 1 |
Thanks sound wisdom, my concern besides pressure is the bullet in the case far enough? Qill it cause an issue since it is not deeper in case?
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Joined: Sep 2010
Posts: 4,004
Campfire Tracker
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Campfire Tracker
Joined: Sep 2010
Posts: 4,004 |
Why are you changing .135 in one jump? Why not try .010, .020, etc. off the lands first. Also you should have enough bullet in the neck to give adequate neck tension and maintain straightness. Will a 2.890 OAL cycle through your action OK?
I am continually astounded at how quickly people make up their minds on little evidence or none at all. Jack O'Connor
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Joined: Jun 2001
Posts: 10,790 Likes: 1
Campfire Outfitter
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OP
Campfire Outfitter
Joined: Jun 2001
Posts: 10,790 Likes: 1 |
I started with the recommended coal of 2.775, referenced hodgon. I did a typo on the 2.755. I decided to then use the powder charge that worked, which was max and compressed. I will download and work up again at the 2.890 then move back in .30 increments to see which is best?
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Joined: Dec 2004
Posts: 14,488
Campfire Outfitter
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Campfire Outfitter
Joined: Dec 2004
Posts: 14,488 |
As long as enough shank is in the neck to keep the bullet from wobbling and wandering, there should be no problem with shallower seating. Either your throat dimensions or magazine box will determine maximum COAL otherwise.
FWIW, I always try to start about 0.020" or so off the lands. I have found that with bullets I use, about 0.020" to 0.030" off the lands seems to work. Some bullets might like longer jump, some less.
Don't be the darkness.
America will perish while those who should be standing guard are satisfying their lusts.
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Joined: Dec 2004
Posts: 14,488
Campfire Outfitter
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Campfire Outfitter
Joined: Dec 2004
Posts: 14,488 |
I started with the recommended coal of 2.775, referenced hodgon. I did a typo on the 2.755. I decided to then use the powder charge that worked, which was max and compressed. I will download and work up again at the 2.890 then move back in .30 increments to see which is best? Many will tell you that large increments is the way to go, and they're speaking from their own experience. I sometimes vary by about 0.003" increments or decrements, but have resorted to 0.020" or 0.030" increments a time or two. If it can be predicted, it's beyond my talents and expertise.
Don't be the darkness.
America will perish while those who should be standing guard are satisfying their lusts.
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Joined: Aug 2005
Posts: 28,259 Likes: 6
Campfire Ranger
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Campfire Ranger
Joined: Aug 2005
Posts: 28,259 Likes: 6 |
Like RiverRider, I always start at max mag length, or .020 off the lands, work up to pressure, then tweak seating depths. When seating deeper I also proceed in .02 increments. 2.890 is about max in my 6.5 CTR.
It is irrelevant what you think. What matters is the TRUTH.
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Joined: Oct 2008
Posts: 7,263
Campfire Tracker
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Campfire Tracker
Joined: Oct 2008
Posts: 7,263 |
Seating a VLD type bullet into the lands may produce the best accuracy, this especially in a target chamber. It is not desirable for a hunting load. I chased the lands in one 243 and when I use it in another the bullets want to stay in the barrel. I had assumed a longer seating was good for the single shot but it turns out to have a shorter throat than my Rem. short action. I start long just short of magazine length and work backwards. If best accuracy occurs when you are back to the original seating depth then it could be worthwhile to try smaller increments. Frequently there will be more than one optimal seating depth.
Oops I just reiterated JGRaider and RiverRider.
"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli
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Joined: Jun 2001
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Campfire Outfitter
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OP
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Thank you for all for the input. This is great place to get knowledge and help from
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