Fine tuning COAL.

[argrendel]

on the Berger website they talk about how to tune their VLDs and Hybrids. Either start touching the lands or max mag length. Load 6 (2 groups of 3). Then load 6 .030" shorter. And last load 6 .060 shorter. One will be noticeable more accurate.

My question is, would that apply to all bullets? SMKs? I would think so, but...

Thanks,

Terry

 

[Joe Salt]

When you start into the lands you only have one way to go. I start there, then depending on what I see in the groups whether I move it five thou. or maybe twenty thou.

Joe salt

 

[savagedasher]

I shoot Hybrids and I start .015 out . .022 to .025 seems the best . Larry

 

[Lapua40X]

I start at about .15 - .20 out, depending on the caliber, but Joe salt makes a good point. If you start in the lands you only have one way to go and if there's a sweet spot between the lands an .15 - .20 out I'm missing it so I may have to rethink it. I'd never start with jammed loads but touching the lands might be worth a try.

 

[argrendel]

I was thinking the 6.5 130g hybrids in my Grendel. So I would start magazine length.

 

[savagedasher]

In how far ? Larry

 

[dmoran]

argrendel -
For coming out of a clip/magazine, I suggest to seat the bullets to fit the magazine with adequate clearance at optimum position for feeding, then tune the load with the powder charges and neck tension, and leave the seating depth alone.
My 2-Cents
Donovan

 

[Mozella]

I think the Berger VLDs are a special case. I always do load testing first with a jump of .010" for non VLDs. Then I usually do seating depth tests for conventional bullets between .020 jump and .010 jam in .005 increments to start with, and fine tune both load and seating depth from there. I study and graph the results and always find a seating depth which is better than the others.

But I had trouble getting the expected performance from Berger VLDs. Berger's instructions struck me as a bit daft at first, but I went ahead and experimented with MUCH larger jumps than I would have if I followed my past practices.

Sure enough, I now have a competition load using Berger VLDs which I jump .080" in one of my F/TR guns. It appears to me that the folks at Berger know what they're talking about.

It still strikes me as a little odd, but these particular rounds with the long jump work well enough so that I finished first place in the F/TR class match last Saturday. By the way, I also shoot VLDs in F-Open class using a 6mm BR Norma but it prefers a jump of .005". Each gun is different and that includes your gun too.

So I would recommend following Berger's suggestions for finding an optimum seating depth for VLDs.

 

[Endyo]

argrendel -
For coming out of a clip/magazine, I suggest to seat the bullets to fit the magazine with adequate clearance at optimum position for feeding, then tune the load with the powder charges and neck tension, and leave the seating depth alone.
My 2-Cents
Donovan

My handloads for my REM 700 /w internal box mag are fit to magazine length. It shoots roughly 1/2MOA. With a box magazine and shorter barrel my expectations aren't for it to shoot any better. I'd imagine it's adequate out to 600 yards.

I would think tuning COAL would be reserved when single loading a rifle whether bypassing the magazine altogether or using a Bob Sled.

Bryan Litz suggested for the Hybrid's, "Not really sensitive. 0.015 off, 0.030 off, 0.045 off, 0.060 off with minimal change in group sizes. Start off the lands. I try to avoid into the lands since it may lodge the bullet unless that is the only option."

However, others on these forums have stated you can jam up to 0.015" without fear of pulling a bullet.

So there's no hard and fast seating depth test. I think the bullet's profile will dictate and in your case magazine length will dictate what you decide to do.

I really like Joe Salts advice. It's simple and smart. Start with jam and work out.

 

[BoydAllen]

The method that is described in the Berger manual is different from previous methods. It is significantly different, and apparently it works. For that reason I suggest that everyone read and think about it before advising that some other approach be used. As to the question as to whether the method works for other bullets, I asked that very question of a Berger tech, who was kind enough to send me a PDF of that section of the manual so that I can share it with my friends. (I have the Berger manual.) He said that it does work for other types of bullets, and since then, I have see evidence of that, if not for the exact method of workup, at least for the range of jump.

Previously I would have never believes that such great amounts of jump would have yielded satisfactory, much less excellent accuracy. IMO we all owe ourselves the opportunity to read and consider this new discovery.

None of this is to say that other methods do not work, just that trying a different way may allow you to find good results when traditional methods have not.

 

[Paddyd]

Reading this it would seem that Berger has abandoned their initial policy of jamming their bullets. I think their new method is the way one would possibly work up a COAL for any bullet style.

 

[argrendel]

Thank you all for your advice and insight. Boyd, glad to know I wasn't the only one wondering about this one. I'll give her a try this weekend.

 

[Endyo]

Thank you all for your advice and insight. Boyd, glad to know I wasn't the only one wondering about this one. I'll give her a try this weekend.

Lol, I read that article last night and decided they were smoking something and loaded my own COAL OCW test (180gr Hybrids - 284). Just finished shooting today. Looks like I was in the right spot all along Jump of 0.010-0.020. My rifle didn't seem to like Jam at all. I may load a few more extra long just to see.

 

[Patch700]

With respect to using bergers method and would it work with other types of bullets , I have used their method with Lapua secant ogive bullets.

The proof for me was when I was finding nodes where I normally would have never thought. .040"-.055" jump for example with a double based powder where I normally found them to shoot nicely with a good amount of jam.

I would definitely recommend trying their way of finding a seating depth with either tangent or secant ogive profiles.

 

[Endyo]

I'm calculating numbers from my Seating Depth Test:

Jamming increased velocity by 10-20FPS.
Jamming produced better groups by 0.08" on the day but the ES were higher on AVG (6)
The Jump numbers were lagging just below 2800FPS (My accuracy node has been around 2820FPS)
My normal Jump of 0.018" and 51.4grs produced higher velocities (+20FPS) yesterday which is unexplained. It was colder by 20 degrees yesterday.
___________________________________________________________
284WIN - Bartlein 1:9, 32" Berger 180GR H4350
___________________________________________________________
Jam 0.030" AVG Speed 2822FPS
Group 1 - 0.461" ES 8
Group 2 - 0.162" ES 13

Jam 0.018" AVG Speed 2813FPS
Group 1 - UNK ES 18
Group 2 - 0.09" ES 23?!

Jam 0.010" AVG Speed 2807FPS
Group 1 - 0.457" ES 23
Group2 - 0.483" ES 6

Avg Group Size: 0.314"
Avg of ES: 18.2FPS
___________________________________________________________
Jump 0.003" AVG Speed 2804FPS
Group 1 - 0.416" ES 21
Group 2 - 0.579" ES 14

Jump 0.013" AVG Speed 2803FPS
Group 1 - 0.583" ES 11
Group 2 - 0.162" ES 7

Jump 0.030" AVG Speed 2795FPS
Group 1 - 0.461 ES 9
Group 2 - 0.162" ES 12

Avg Group Size: 0.394"
Avg of ES: 12.3FPS
___________________________________________________________
I'm wondering if better groups are due to the Jammed bullets being within my known accuracy node of 2800FPS < but the higher ES is due to increased pressure caused by jamming.

 

[savagedasher]

I use seating depth to adjust my ES . But I do my tuning with a tuner . Larry

 

[Endyo]

I've heard a tuner mentioned many times. I'm not familiar.

 

[savagedasher]

Check RAS tuners .or Bostrom Gunsmiths . Larry

 

[dmoran]

I'm wondering if better groups are due to the Jammed bullets being within my known accuracy node of 2800FPS < but the higher ES is due to increased pressure caused by jamming.

Endyo -
An accuracy advantage to being in close proximity and in contact with the rifling can be from alignment improvements.
The improvements come from the bullet being pushed into alignment with the bore when making contact with the throat/rifling in its placement when chambered. Then by being pre-aligned, when it is fired its running true, square and straight with the bore, instead of having to be engaged from a jump and potential misalignment aspects that can come from jumping to the lands.
My 2-Cents
Donovan

 

[Endyo]

Endyo -
An accuracy advantage to being in close proximity and in contact with the rifling can be from alignment improvements.
The improvements come from the bullet being pushed into alignment with the bore when making contact with the throat/rifling in its placement when chambered. Then by being pre-aligned, when it is fired its running true, square and straight with the bore, instead of having to be engaged from a jump and potential misalignment aspects that can come from jumping to the lands.
My 2-Cents
Donovan

Dmoran,

I thought of that possibility, but I didn't have any hard evidence to back it up. Glad someone else with experience mentioned it.

I'm very happy from the accuracy gain but unless I can get the ES to match the Jump loads I will have to keep searching.

Hope these contributions help the OP with his test, maybe his findings will mirror mine.