mikee Posted September 28, 2009 Report Share Posted September 28, 2009 when changing between ammo brands, bullet weights and bullet types, eg BT and SP, would the point of impact only change in the vertical plane or would they also change horizontally assuming a dead still day and a steady rifle hold, or could i change between bullet types without altering the scope and still hit what i was aiming at, at sensible-ish distances, say out to 250yds, fox size target not a 1" target sorry if this is a daft question mikee Quote Link to comment Share on other sites More sharing options...
AndyCM Posted September 28, 2009 Report Share Posted September 28, 2009 You'll have to test - if you get lucky...great. They can go horizontal - harmonics & nodes you know ! Quote Link to comment Share on other sites More sharing options...
mikee Posted September 28, 2009 Author Report Share Posted September 28, 2009 You'll have to test - if you get lucky...great.They can go horizontal - harmonics & nodes you know ! could you explain please andy mikee Quote Link to comment Share on other sites More sharing options...
Baldrick Posted September 28, 2009 Report Share Posted September 28, 2009 (edited) Andy is right, Mike - you will inherently get variation in both horizontal and vertical planes (barrels don't just vibrate in an up and down direction). There's too many variables, some almost imperceptible, that you have to account for. In lay terms, all barrels will have what's best defined as a 'sweet spot' (think resonance), where the barrel's vibration is optimised. It's not something that can be measured, so you just have to experiment. Some rifles will shoot better with a massive moderator dampening vibration, and some won't. Furthermore some calibres have a reputation for relatively minimal variation in POI when altering bullet weight, such as the .270 Win. Sadly the .243 appears not to be one of those calibres. Like I said, you can't predict POI shift unless you've put in plenty of time behind the trigger of that specific rifle. The best advice I can give you is just to apply trial and error, whilst being mindful of your rifle's twist rate and your intended quarry. I imagine your Ruger has a 1:10 twist and therefore you should stick to the 87-100gr weight for starters. And once you've found a load that suits your rifle, stick to it like glue (either make up a large quantity on your reloading press, or buy as much as you can from the same factory batch off your dealer). Don't muck about with trying to remember and adapt multiple zero points. A good deer-specific bullet will demolish a fox etc, negating the need for a foxing round in most scenarios. Edited September 28, 2009 by Baldrick Quote Link to comment Share on other sites More sharing options...
mikee Posted September 29, 2009 Author Report Share Posted September 29, 2009 cheers Baldrick ive just spent a while trawling the net but cant find it now, i previously found some tech data and from memory the twist rate quoted was 1:9 1/8 i'll just stick to the 100gn Hornady SP's for everything, like you say, they are gonna mess up a fox and it will avoid ever loading the wrong bullet for what i'm going to shoot mikee Quote Link to comment Share on other sites More sharing options...
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