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what size groups

 
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  #8  
Old 04-30-2006, 05:36 AM
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Join Date: Feb 2006
Location: Nottingham, UK
Posts: 261
Re: what size groups

[ QUOTE ]
Well those groups arn't bad but I'm sure that with some work they can be closed up some.
You diden't mention what barrel your shooting as far as brand , lenght , twist rate.
What is your load data like , what powder , primers ,brass what dies are you using. Are you shooting fire formed brass or is this the forming loads?

Granted you have a great action but the action is a samll part of the puzzel accuracy wise , I have put together Savages that will shoot that well but they were wearing good barrels and their was alot put into the loading.
Another question is who did the building?

[/ QUOTE ]

its a Krieger #7 25" 1 in 10 twist.
i am using VV n165 (49.6g) federal gold medal match 210 primers.lapua fire formed brass (once fired)
redding competition seating die,redding competition bush neck die.

it is a 270 tight neck,brass neck lathed to .267 with a .265 bush

rifle built by nesika.

i have done the primer pockets,deber, Wilson case trimmer,(trimmed to the shortest case) rcbs rockchucker press.

but i only shoot of a by pod and rear rest.
thanks for your help
Colin
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  #9  
Old 04-30-2006, 05:37 AM
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Join Date: Dec 2005
Posts: 2,114
Re: what size groups

[ QUOTE ]
How can a get a 2" group at 500yds and a 1" group at 100yds in theory you should have a 5" group at 500yds if the gun shoots to 1 moa at 100yds correct?

[/ QUOTE ] In theory, longer range groups will be larger than shorter range ones because bullets leaving at a slower speed drop more from gravity and drift more from non-still air movement than faster ones. And bullet drop and drift is not proportional to range. Check some ballistic tables and see what the drop and drift difference is at 100 yards for the same bullet 30 fps apart around 3000 fps, then check their drop and drift at 500 and 1000 yards; it ainít 5 and 10 times as much.

[ QUOTE ]
but how can a gun group to a tighter moa at a longer range than at a short range.

[/ QUOTE ] Easy. Shoot one group at one range, then hold and shoot better one at another range. The longer range one will usually be smaller in moa. Shoot through screens at both ranges and this wonít happen unless the bullets are so poorly balanced they donít spin stabilize in their first few dozen yards of flight; but these aren't very accurate anyway.

An exception is when positive compensation causes slower bullets to leave when the muzzle axis is elevated a bit more than when faster ones are fired with the muzzle axis a bit less of an angle. Their two trajectories cross at some down range point which was common for ammo with large muzzle velocity spreads. British SMLE .303's are notorious for this with their ammo loaded with Cordite and their rear-locking bolt and receiver design. Never happened with Mauser style bolt actionís front locking lugs shooting the same ammo.

[ QUOTE ]
As for the bullets having to leave the muzzle at the same velocity that to is false , I have owned guns that have had extreme spreads of as much as 30fps and would shoot under Ĺ moa out to 400yds.

[/ QUOTE ] With a Sierra 30 cal. 190-gr. HPMK having a 30 fps spread around 3050 fps, that will not cause vertical shot stringing more than about .04inch at 100 yards; thatís .04 moa. At 400 yards, itís gonna have about a .72-inch vertical spread or .18 moa. Way down at 1000 yards vertical stringing is about 6.7 inches or .67 moa. Horizontal spread also gets non-uniformly bigger even when the air's moving in all directions only one-half mph. For each hundred yards of range the bullet goes through, the more it moves sideways from the same slight air movements because it takes longer to traverse each hundred-yard segment. Wind drift curves look much the same a bullet drop curves; they're horizontal and the drop's vertical. So groups open up in their subtended minutes of angles in all directions.

[ QUOTE ]
sometimes things happen and nobody knows why when in theory it should never be close to possible

[/ QUOTE ] When the realities of bullet flight are learned, itís all understood.
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  #10  
Old 04-30-2006, 05:55 AM
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Re: what size groups

Well, as JD says, the barrel is important The Berger 95 VLD is much better with a 1-9 twist barrel. It is possible that you only have the bullet marginally stabilized and things will get worse with distance as velocity decreases and spin de-stabilizes.

Try the Sierra 70 gr MK. It doesn't have a high BC but it shot great for me in a 1-10 twist.
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  #11  
Old 04-30-2006, 01:33 PM
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Join Date: Oct 2004
Location: Northamptonshire England
Posts: 676
Re: what size groups

Col,
Your stock pattern is very effective camouflage against your carpet, i can hardly see it [img]/ubbthreads/images/graemlins/laugh.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img]

Seriously though,I think your combo should be giving you 1/2 moa for all the ranges you stated, a lighter bullet may be beneficial.
I have been having excellent results with 90grn Scenars out of my 243AI. I am currently refining loads with H4831 behind these bullets, this powder is showing the most promise out of the powders i have tried so far (H4350ext, H414 and Re22).
Cases, primers and prep are the same as you use.

Ian
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  #12  
Old 04-30-2006, 01:54 PM
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Join Date: Feb 2006
Location: Nottingham, UK
Posts: 261
Re: what size groups

[ QUOTE ]
Col,
Your stock pattern is very effective camouflage against your carpet, i can hardly see it [img]/ubbthreads/images/graemlins/laugh.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img]

Seriously though,I think your combo should be giving you 1/2 moa for all the ranges you stated, a lighter bullet may be beneficial.
I have been having excellent results with 90grn Scenars out of my 243AI. I am currently refining loads with H4831 behind these bullets, this powder is showing the most promise out of the powders i have tried so far (H4350ext, H414 and Re22).
Cases, primers and prep are the same as you use.

Ian

[/ QUOTE ]

hi m8
i have some h4831 sc what is your max load for that weight bullet.i am beginning to think that the 95 VLD is just a tad to much for my gun.re tried the same groups today and and everything is the same at 100y. not bad but i know this gun should shoot better than this.
thanks everyone for the help,and keep it coming.
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  #13  
Old 04-30-2006, 02:30 PM
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Join Date: Sep 2002
Location: Nebraska
Posts: 264
Re: what size groups

Have you tried shortening your seating depth? I have had best results with vld's off the lands. I just finished up a OCW test for my Rem 260 with Bob Cauterucio's 120gr VLD's. They are close to .030 off the lands. The circled group is my confirmation of my OCW load of 48.3gr. Group was shot at 220yards off a pedastal. Only second time shooting off the pedastal and the two shots right and left are called flyers. 6 shots total. 2shots at 48gr,2 at 48.3gr and 2 at 48.6. With the flyers just a tad over 1/2 moa but the 4 shots clustered measure right around .7" The other groups are seating depths that increase the overall.

So try backing them off and see how it does.

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  #14  
Old 05-01-2006, 01:40 PM
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Join Date: Oct 2004
Location: Northamptonshire England
Posts: 676
Re: what size groups

Hi Col,
I have worked up to 49grns of H4831 but i am not using the short cut.
I think i could get 50 grns in and maybe a bit more if i change to the SC.
Velocity averaged over 10 shots at 3142fps, a bit dissapointing but showing very promising accuracy.
47 grns of H4350 gave me velocity just 7fps short of 3400 with 90 grn Scenar and 3210 with a 105 Scenar and i reckon i could get in another 2 grns under the 90.
Both these load also showed promising accuracy.

Ian.
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