gixer1 Posted April 21, 2012 Report Share Posted April 21, 2012 (edited) Took my 243 out today to give it a check and have a play with my new target (see other post) an I have a days red stalking coming up so wanted to put some 100gn soft points through the rifle as I've never used them in this rifle as its new. Checked the zero with a 3 shot group with my usual 75gn BT's first , all fine and about an inch above point of aim at 100 yards which is where I set it up to be - Then at the same distance put a 3 shot group in with the 100gn sp's and the below was the result which is absolutely fine for stalking but I'm a bit baffled by the poi move to the right? :blink: and ideas?? I should add I shot another shot group with 75's and another with 100's and the results were pretty much identical... I had intended to buy a decent scope to mount on this rifle while in the states but from the groups I'm getting with the cheap hawke nite-eye I put on it I'm thinking why bother changing it! I should also give my "range master" a mention, first time out with me and the guns an he loved it! Regards Gixer Edited April 21, 2012 by gixer1 Quote Link to comment Share on other sites More sharing options...
matone Posted April 21, 2012 Report Share Posted April 21, 2012 Saw similar results with my own .243 ,ie lateral and vertical change to poi with different ammo. Havn`t an explaination sorry! Quote Link to comment Share on other sites More sharing options...
artschool Posted April 21, 2012 Report Share Posted April 21, 2012 see the same with my 223 moving from target ammo to ballistic tip. Quote Link to comment Share on other sites More sharing options...
gixer1 Posted April 21, 2012 Author Report Share Posted April 21, 2012 Now I'm wondering if I centred the 100's would it move the 75's the same distance left :blink: Quote Link to comment Share on other sites More sharing options...
onslow52 Posted April 21, 2012 Report Share Posted April 21, 2012 A lot of its to do with barrel harmonics.Same thing happens on my 22benchrest rifles, even when using the same ammo turning the barrel tuner, even with only moving the tuner a couple of thou can move the shot up down left or right which is used to get more consistency even from tenex.Same as increasing or decreasing powder amount in fullbore which adjusts harmonics of the barrel and changes point of impact as a tuner is not allowed. Quote Link to comment Share on other sites More sharing options...
soulboy1957 Posted April 21, 2012 Report Share Posted April 21, 2012 What mr onslow52 said,different weights can do different things as the barrel vibrates as its fired,i was told its to do with the length of time the bullet is in the barrel i.e. heavier bullets slower/in the barrel a fraction longer. Ive had heavier 105g bullets shoot 2" higher than 70g in my .243 @100 yards....due to again bullet in the barrel longer whilst the gun is recoiling upwards......or so i was told.... Quote Link to comment Share on other sites More sharing options...
Frenchieboy Posted April 22, 2012 Report Share Posted April 22, 2012 I have the same situation with my .243 if I change ammunition. I normally keep my rifle zeroed up to shoot 1 inch high at 100 yards using 75g "Home Loads" which I use for Foxes, but if I want to change to S&B 100g for Deer I find that the POI shifts to 2.5 inches low and 2 inches left - The situation is almost identical if I try it with PRVI Partizan 100g too. I can understand the POI being lower but I have never understood why it should shift to the left with a heavier bullet. It doesn't worry me as it is quite consistent so zeroing for the different ammunition isn't too expencive or time consuming as I know in advance how many clicks to give it to put me almost straight on before firing the rifle with the different ammunition! Quote Link to comment Share on other sites More sharing options...
bicykillgaz Posted April 22, 2012 Report Share Posted April 22, 2012 I hate to point out the obvious but maybe your truck isn't the best idea for a safe back stop, I'm very surprised your range official didn't point this out, I guess we can put it down to his inexperience though and let him off just this once! I thought it happened with all ammo if I go from eley subs to Winnie subs I get a change of poi. Quote Link to comment Share on other sites More sharing options...
MiLisCer Posted April 22, 2012 Report Share Posted April 22, 2012 Push the target out to 200 yards and you may well find the 100's are not shooting centre of target (But still lower than your 75's) If you plan on taking your Red's within 100 yards then re-zero to the 100s - if longer shots 150-200 are to be taken then zero at that range - it will give you a better idea of how the 100's perform at that range - they may have stabalised better and "settled" Some of my target loads are "loose" out to 400 but tighten at longer distances. Mike Quote Link to comment Share on other sites More sharing options...
gixer1 Posted April 22, 2012 Author Report Share Posted April 22, 2012 Push the target out to 200 yards and you may well find the 100's are not shooting centre of target (But still lower than your 75's) If you plan on taking your Red's within 100 yards then re-zero to the 100s - if longer shots 150-200 are to be taken then zero at that range - it will give you a better idea of how the 100's perform at that range - they may have stabalised better and "settled" Some of my target loads are "loose" out to 400 but tighten at longer distances. Mike Mike, I had Planned to check this at 200 too as I wondered if this may be the case. Fister - that makes perfect sense about where in the harmonics rotational area it is Regards, Gixer Quote Link to comment Share on other sites More sharing options...
Harnser Posted April 22, 2012 Report Share Posted April 22, 2012 You silly old tart Gixer ,you have got the target upside down . Harnser . Quote Link to comment Share on other sites More sharing options...
deershooter Posted April 22, 2012 Report Share Posted April 22, 2012 Bullets travel like a corkscrew with a heavy bullet it impacts in a slightly different place saw this in a mag years ago where they set up rice paper targets at 50 yard intervals from 100 -300 yards Deershooter Quote Link to comment Share on other sites More sharing options...
Redgum Posted April 22, 2012 Report Share Posted April 22, 2012 Im possibly wasting my breath here but the barrel oscillates radially in terms of its harmonic vibration in the opposite diection to to the bullet, think of a helicopter with no tail rotor to stabilise the torque from the main rotor. The release point of the bullet within that radius of oscillation is what causes the zero position to alter and as long as it is consistent is nothing to worry about. At 100 yards i hear people call a bullet zeroing low as being "slower" but this is not correct, it merely exits the barrel within a different spot within the harmonic cycle. Pretty good description of how I understand it, as said the best possible situation is to zero for the ammunitoin and range that you will be firing at. From what I have seen the better the quality the barrel the less oscillation, a sako will(normally) shoot a wider range of ammunition more accuratly than say a Remington. Reason I mention Remington is that my 700 is very ammo fussy but with the correct loading will shoot great groups with both 100gr and 85gr sierras, the 85gr shoot half an inch higher which is no problem. This is the great thing about homeloading, you can adjust many factor's so the bullet jumps the gun at the correct time in relation to the harmonics, a custom rnd for the barrel. That said your groups are very good, is that factory ammo or reloads, both groups will make a deer very dead at that range. Quote Link to comment Share on other sites More sharing options...
gixer1 Posted April 22, 2012 Author Report Share Posted April 22, 2012 Pretty good description of how I understand it, as said the best possible situation is to zero for the ammunitoin and range that you will be firing at. From what I have seen the better the quality the barrel the less oscillation, a sako will(normally) shoot a wider range of ammunition more accuratly than say a Remington. Reason I mention Remington is that my 700 is very ammo fussy but with the correct loading will shoot great groups with both 100gr and 85gr sierras, the 85gr shoot half an inch higher which is no problem. This is the great thing about homeloading, you can adjust many factor's so the bullet jumps the gun at the correct time in relation to the harmonics, a custom rnd for the barrel. That said your groups are very good, is that factory ammo or reloads, both groups will make a deer very dead at that range. Redgum, Thanks, would love to say its me but it's mostly down to a cracking rifle, believe it or not all groups are with factory ammo, the 75gn are Norma and the 100gr are ...wait for it.....prvi! £11/20! This setup will join the dots all day long if I do my bit from what I've seen so far,that's what I meant when I said I loath to change the cheap hawke nite-eye I have sittin on it just now!!! Harsner, You mean to tell me with all those years experience no one has ever shown you how to shoot Aussie style?? Regards, Gixer Quote Link to comment Share on other sites More sharing options...
gixer1 Posted April 22, 2012 Author Report Share Posted April 22, 2012 I hate to point out the obvious but maybe your truck isn't the best idea for a safe back stop, I'm very surprised your range official didn't point this out, I guess we can put it down to his inexperience though and let him off just this once! I thought it happened with all ammo if I go from eley subs to Winnie subs I get a change of poi. Yeah, the insurance company are starting to question the claims! Quote Link to comment Share on other sites More sharing options...
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