Lower POI by upping velocity?


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BsChoy
July 26, 2007, 06:16 PM
I have a 6.5x55 swede that shoots about 8-10 inches high at 100 with 140 grain bullest. I know they were battle sighted for 300 yds and I can replace the front sight blade with a taller one but, is it feasible to use a 129 grain and speed it up to bring POI down? Just wondering.

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R.W.Dale
July 26, 2007, 06:33 PM
I have a 6.5x55 swede that shoots about 8-10 inches high at 100 with 140 grain bullest. I know they were battle sighted for 300 yds and I can replace the front sight blade with a taller one but, is it feasible to use a 129 grain and speed it up to bring POI down? Just wondering.

I found that when shooting my AG42B in that caliber The groups would print almost exactly as you describe with anything weaker than full throttle loads with 140g bullets.

2300 FPS would print almost a foot high 2450 FPS would be dead on. Yes you read that right the more powerfull load would print LOWER than the weaker loads.

wcwhitey
July 26, 2007, 07:05 PM
You are correct in assuming that the lighter bullets will lower you POI. The reason behind this is that velocity will increase because of the lighter bullet. As
Krochus mentioned increasing velocity without changing bullet will do the same. LOL Bill

USSR
July 26, 2007, 07:06 PM
2300 FPS would print almost a foot high 2450 FPS would be dead on. Yes you read that right the more powerfull load would print LOWER than the weaker loads.

Exactly as it is supposed to be. High velocity loads will have a lower POI than lower velocity loads at close range.

Don

BsChoy
July 26, 2007, 10:33 PM
In your opinions would the poi move enough to make it close to poa (within 3 inches or so)?

Fatelvis
July 27, 2007, 02:26 PM
Bumping up the velocity will lower the group, but not 8-10 inches. I would say about half of that. If you are planning on doing alot of shooting at that distance, I would install a higher front sight.

R.W.Dale
July 27, 2007, 06:38 PM
In your opinions would the poi move enough to make it close to poa (within 3 inches or so)?

It did with my swede. Only i just pumped up the load and stayed with the same 140grn bullets

BsChoy
August 18, 2007, 10:07 AM
Update to the thread....

I broke down and called Samco for a tall +3.5 sight. Well after a small amount of file,shoot,file,shoot I have it zero'd with 47.0 grains of RL22. I reblued the sight and it now works with the Mojo rear and all is well. It goes to show....if you throw money at most problems they go away lol

Ol` Joe
August 18, 2007, 10:24 AM
I find in my 6.5x55 a 129 gr bullet at around 150 fps faster velocity then a 140 gr will hit within 2-3" of the heavier bullet. The POI is not always lower and almost never in a totally verical line, there is always some left/right change too due to altered barrel vibration.
This is a rebarreled commercial rifle with a scope sight, not a iron sighted milatary rifle. The velocities of both loads are a bit above commerial ammo also.

peterotte
August 18, 2007, 08:01 PM
BsChoy another possibility (if you can do or know someone who will do it for you) is to make a muzzle blast deflector that sits in front of the foresight and overhangs the muzzle about 1/2 inch or less, secured with low temp 'loctite' (so it can be removed with a candle flame). All that does is slow the barrel vibration a tad and can have the same effect as higher velocity. It costs nothing and reduces muzzle blast levels for the shooter. (The guy at the muzzle end gets more but then he's in the wrong place anyway:uhoh:).

Regards
Peter

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