6.5-284 Accuracy Problems

[Hilmisson]

I have a problem I have custom rifle that's about 5 months old and has been shot about 150 rounds.

Rifle info:
Cal: 6.5-284 Norma
Action: Stiller Tac 300
Barrel: 26" Shilen Stainless Steel Bull barrel 1-8" twist w/muzzle brake
Stock: Bell and Carlson tactical
Trigger: Jewell set to 10oz pull weight
Scope: Leupold Mark 4 ER/T 8.5-25x50mm
Cases: Lapua trimmed to 2.161"
Primers: Fed Gold Medal Match

I intended to shoot bullets in the 130-142 gr range and so far I've tried 130gr Berger VLD, 139gr Lapua Scenar, and 140gr A-Max. I've loaded each of these bullets with 3 different powders; H1000, H4831sc, and VV N160. With each powder and each bullet I've loaded at least 3 different loads.
The Scenar has performed best out of the three but the groups are still quite pathetic.

So far I'm averaging about 3" groups or worse at a 100 yards!
I also tried a 95gr V-max and no matter what powder I used it performed BETTER than the heavy target bullets.

Does anyone have any suggestions on what to try next? I've trimmed all my cases and then sorted according to weight. I'm confident that my scale is accurate (analog Redding), Redding Comp. dies with bullets seated very close to the lands without raming them in.
Any suggestions are greatly appreciated.

 

[mr45man]

3" at 100 WHAT? WOW that is unheard of
#1 I would say something with the scope/mounts is f d up.
#2 action screws
#3 barrel / muzzle brake is loose ?
It is NOT your loads/scale/ bullets/brass/ powder
John H

 

[rabbit fingers]

Agreed. Also have you verified it IS a 1 in 8 twist. Ie. measured it yourself?

 

[gatorman]

How much are you asking for it?

Like they said check the twist to be sure...And maybe,as I have found with
some bullets,they need to jumpmore into the rifleing.So try seating a little deeper
with a few...Good luck..

 

[Hilmisson]

3" at 100 WHAT? WOW that is unheard of
#1 I would say something with the scope/mounts is f d up.
#2 action screws
#3 barrel / muzzle brake is loose ?
It is NOT your loads/scale/ bullets/brass/ powder
John H

I'll look at my gear and see if something is moving

How much are you asking for it?

Like they said check the twist to be sure...And maybe,as I have found with
some bullets,they need to jumpmore into the rifleing.So try seating a little deeper
with a few...Good luck..

I called Shilen and they confirmed that they sent me a 1-8" barrel, Do you know any methods of measuring the twist without taking it to a gunsmith?

Thanks for the replies!

 

[mr45man]

If you have another scope to use, that would be a good test.
Even the best scopes can fail.

John H.

 

[ava123]

I have had the same problem with a 308, and the same scope you have mentioned. the groups were always changing, with one or two shots out of the group, not by alot, but signifigant at 100 yds. I changed the scope to a fixed power and things settled right in to what I had expected. I sent the scope back to factory, they went thru it, and I put it back on the rifle today and will see how it does this morning. I have some new in the box Federal 308 match and so I know that this stuff will shoot well and will give it a try this am.

 

[DennisH]

Do you know any methods of measuring the twist without taking it to a gunsmith?

Use your cleaning rod. Insert it going towards the muzzle, when the rod comes out at the muzzle, put your cleaning brush on. Pull the rod into the barrel about 2", mark the rod with a silver marker, or put masking tape around the rod and mark it. Then pull the rod until the mark makes a full revolution and is sitting in the same place you marked it. You can use the reciever as a reference point. Then measure the distance from your first mark to your reference point. If it's 9", then you have a 9 twist barrel.

You can do this in reverse, might be easier. Just start from the muzzle, mark the rod at the crown, and pull the rod out making sure your brush is in the lands. Should work with a bore mop as well.

 

[LCazador]

You could be having a scope problem , change scopes and check the base and rings for proper screw torque . Are you torqueing the ring screws with an inch pound wrench ? Any more than 20 inch pounds and you could be over tightening the screws . Get a tight fitting brush on the end of your cleaning rod , add some lube , push the brush into the rifleing about two inches , and then make a mark with a sharpie on the rod . Measure the distance from the mark to the back end of the action , now push the rod into the bore till the mark makes a full turn . Measure the distance now between the mark and the same place on the back of the action you measured to before . Subtract this new measurement from the original measurement , the measurement will be the twist of your bore .
One more thing , take the brake off and shoot it without the brake to see if groups improve .

 

[drop_point]

My 6.5-284 that I had shot great with a 1:8 #7 Shilen with RL22 and 140 VLDs jammed .015" into the lands. Also, mine didn't want to shoot until it was fouled.

 

[Hilmisson]

Thanks to all of you that responded. Last weekend I finally got somewhere with this rifle. I decided to jam the bullets approx. .02" into the lands and did that with the 139 Scenar, 140 A-Max, and the 140 SMK. All of them shot groups under 1" and some of the loads achieved about .7" average (5x 3-shot groups).

I do think there is a lot more to come out of this rifle but this is a breakthrough relative to the nasty 4" groups I was getting before. It seems that the rifle is very sensitive to bullet seating depth.
Can it also just, in some part, due to the "break-in" period?

Thanks again to all of you who responded