Who said 6BR is easy to tune?

[marchx]

Last week I tested different seating depths using 30gr of N140 in 6BR. The most promising was .010 off the lands showing ¼ MOA for a 4-shot group.

Yesterday I loaded 5 rounds to repeat the test in different weather conditions. What came out was a disaster 0.88 MOA (see below). It was a vertically dispersed group.

It was virgin Lapua brass trimmed to length, mandrel expanded, graphite lube. I measured the powder chargé on 2 scales and the charges were precise up to 0.02gr. CBTO was consistent up to 0.0005”. 105 Hybrids. I was shooting off F-class bipod and SEB rear bag using x60 magnification.Seeing the heart rate on my reticle but still my point of aim was within the X zone.

Would using a front rest (like seb neo) increase my accuracy or should I stick to my setup and review my reloading process (or is it shooting technique)?

https://imgur.com/04lA0l3

https://imgur.com/QY22U82

 

[Jager]

If you're seeing your heartbeat in your reticle, your rest is a problem. I'd definitely invest in a good front rest.

There are a number of other things that could be going on, too. But since you know the rest is an issue, I'd start there.

 

[Steve Blair]

What is the rifle and barrel?

 

[Chuckhunter]

Cures for Vertical--Speedy Speaks

We've just added a nice article by Speedy on how the reduce the vertical in your groups. It addresses a lot of factors--gun-handling, trigger/firing pin issues, wind-reading, and bag set-up. His focus in primarily on short-range benchrest but there are some great bits of advice for any shooter...

forum.accurateshooter.com

 

[Clancy]

That sure looks like a scope issue. Not saying it is. But straight lines are a major indication.

Could be the hardness of a bag, dirty firing pin, or other things as well.

 

[Chuckhunter]

Cures for Vertical--Speedy Speaks

We've just added a nice article by Speedy on how the reduce the vertical in your groups. It addresses a lot of factors--gun-handling, trigger/firing pin issues, wind-reading, and bag set-up. His focus in primarily on short-range benchrest but there are some great bits of advice for any shooter...

forum.accurateshooter.com

CURES for VERTICAL STRINGING

6mmBR.com is the best guide for 6mm BR Benchrest precision shooting, complete with 6BR FAQ, Reloading Data, Shooter Message Boards, Reader Polls, and Photo Gallery. Match event calendar and rifle competition accuracy training tips. Equipment reviews (.243 bullets, 30BR cartridge, 6mm Norma...

www.6mmBR.com

 

[Big Mc]

Last week I tested different seating depths using 30gr of N140 in 6BR. The most promising was .010 off the lands showing ¼ MOA for a 4-shot group.

Yesterday I loaded 5 rounds to repeat the test in different weather conditions. What came out was a disaster 0.88 MOA (see below). It was a vertically dispersed group.

It was virgin Lapua brass trimmed to length, mandrel expanded, graphite lube. I measured the powder chargé on 2 scales and the charges were precise up to 0.02gr. CBTO was consistent up to 0.0005”. 105 Hybrids. I was shooting off F-class bipod and SEB rear bag using x60 magnification.Seeing the heart rate on my reticle but still my point of aim was within the X zone.

Would using a front rest (like seb neo) increase my accuracy or should I stick to my setup and review my reloading process (or is it shooting technique)?

https://imgur.com/04lA0l3

https://imgur.com/QY22U82

That looks like a stock/rest problem. Vert string usually is. Tommy Mc

 

[marchx]

That sure looks like a scope issue. Not saying it is. But straight lines are a major indication.

Could be the hardness of a bag, dirty firing pin, or other things as well.

It's unlikely. It's my recent MarchHM and a spuhr mount. Rifle is new. 200 through the barrel.

 

[marchx]

@Big Mc kindly elaborate on both
@Steve Blair 25" HV contour, KS Arms, 1:8 twist, Oryx chassis,
@Chuckhunter Thank you. I read that article and it could be 20 different things . For me the problem is to prioritize them in sequence starting from the most popular/common.

 

[Ned Ludd]

At only 200 rounds, your barrel has probably just barely "settled in". In addition, you noted that the conditions were different. I would probably re-visit a charge weight and seating depth test to be certain the load was where it should be within the specific conditions in which the vertically-strung group was fired. You can certainly check to make sure all the screws are tight, but I wouldn't jump to any conclusion that something major was wrong with the rifle/scope setup just yet. Anyone can have a bad day pulling the trigger and a single 4-shot group with vertical stringing doesn't necessarily mean anything other than that. I'd want to see several (4 or 5) groups fired under similar conditions before I made any conclusion and even then, it could still be a load issue, rather than a gun issue.

 

[Chuckhunter]

@Big Mc kindly elaborate on both
@Steve Blair 25" HV contour, KS Arms, 1:8 twist, Oryx chassis,
@Chuckhunter Thank you. I read that article and it could be 20 different things . For me the problem is to prioritize them in sequence starting from the most popular/common.

Marchx I would take off the bipod and shoot it off a good bench with a solid front rest. Make sure your bag isn't rock hard. At least that's where I would start. Hope you get it figured out.

 

[gunsandgunsmithing]

That sure looks like a scope issue. Not saying it is. But straight lines are a major indication.

Could be the hardness of a bag, dirty firing pin, or other things as well.

I agree. That's more than just tune, IMHO. It might be part of it but I'd bet something is inducing that much vertical. I'd try a different front rest setup to see what it does, even just a sandbag. Wind can do it too but straight vertical is not usually just wind. Any number of things it could be. That's part of the fun.

 

[Hoot]

I've seen that with varying degrees of "death grip" on the rifle. IE a bad day at the range... We all have 'em.

Hoot

 

[marchx]

Marchx I would take off the bipod and shoot it off a good bench with a solid front rest. Make sure your bag isn't rock hard. At least that's where I would start. Hope you get it figured out.

Yep. I read Speedy's article again: I don't have enough experience to properly assess half of the factors Speedy is referring to.

 

[Clancy]

When you did the seating depth test, what did the other groups look like? In a BR, the bad ones should be half moa and the good ones .250 or less. Smaller than that if they’re 3 shots.

I’m just asking to help determine if it’s load or equipment related, but it still looks like equipment to me.

I’m not a bipod hater, but inconsistent load would make for a vertical group, and that’s free to fix. It could still be the scope or a bag.

What other bullets and powders did you try in the previous rounds?

 

[Big Mc]

@Big Mc kindly elaborate on both
@Steve Blair 25" HV contour, KS Arms, 1:8 twist, Oryx chassis,
@Chuckhunter Thank you. I read that article and it could be 20 different things . For me the problem is to prioritize them in sequence starting from the most popular/common.

Most of the time i will check torque of the action screws .The 2nd place i look is the stock bedding. Both may cause your problem. Tommy Mc. Dont clame to be a Know It All. But that fixes my problems. I wish you well with your problem.

 

[JEFFPPC]

#1 FLAGS???
#2 How did you come to choose 30.0?????
#3 (related to #2) Describe your process to tune or do you have a process?

 

[gunsandgunsmithing]

#1 FLAGS???
#2 How did you come to choose 30.0?????
#3 (related to #2) Describe your process to tune or do you have a process?

Yes, always use flags, especially so while tuning. Even surveyor tape on 3-4 bent coat hangers down range is way better than nothing. I think the op may have other factors involved too but eliminate wind as much as humanly possible..FIRST THING. Then change one thing at a time starting with easiest/most obvious areas, and progressing to more complex things, like ignition, for example.

Mirage can be brutal this time of year, too.

I agree with Jeff that more info would be helpful. IME, a 6BR truly is one of the easiest rounds to load for.

 

[CharlieNC]

Many potential causes noted, but seeing your heartbeat spells inadequate setup which must be addressed to move down the list.

 

[JFrank]

^^^ yep’ this appears mechanical but I cannot judge one group alone, it really helps to know the previous flag information and tuning groups that lead up to the seating/powder decision.
Jim