Loading the Accubond

[3deers]

I had a bit of unexpected results at the range, with 165g Accubonds recently.

308 WIN
Win 748 - 47.2gr
CCI 250 mag primers

Worked up my max at 10 thou off the lands. (Can probably go hotter, especially as I intended to increase the jump to the lands, but noticed some ejector markings at 47.5 - which is my 165 Partition loading. I just don't see the need to squeeze the last 20 fps out of handloads, like I used to.) Then I planned to increase jump in 0.020" increments.

At 20 thou off, my 3-shot group was 1.25" -- nothing but a promising start.
At 40 thou off, 3 shots measure 2.32"
At 60 thou, 3 shots = 3.33"

This is heading the wrong way !! What are your experiences? Could it be my 700 Remington just likes a shorter jump? I've been reading that the AccuBond likes a long jump, as much as 100 thou. Should I continue, and maybe find a sweet spot at a longer jump? Or go back near the 20 thou length, and see if there's something I can tweak around there?

Your input will save me time and effort, and, as always, is greatly appreciated.

3deers

 

[TackDriver284]

My go to powder for the .308 is Varget, then IMR 4064. It may not like the powder you are using.

 

[3deers]

Thanks, Mark.

I have several loads for this rifle that shoot under 1 MOA with the WIN 748, including 165 Partitions, and Hornady's 165 Interbonds. So, it's kinda my go-to start.

But yes, maybe you're right, and I'll have to move to a different powder with the Accubonds. I would still like to hear a few opinions about my groups getting bigger as I move further from the lands, before I start reinventing my wheel.

Thanks for the input.

3deers

 

[Dwh7271]

I'd think for grins try three at 75 and three at 100 off. May surprise you, may not.
I'd try it before I gave up on them.

 

[TXbaldhunter]

I load 45.5grs of Varget with 165gr bullets in my 308.Win 748 is a bit faster on the burnrate scale than Varget.I'd back off a couple of grains off your 47.2gr load an see if your groups tighten up.

 

[desertcj]

Listen to what the rifle is telling you. Try. 010" and even .005" off the lands.

 

[longrangehunter]

I loaded them much closer..... .0175" - .020" off the lands. Try RL-15, VarGet, or IMR 4064.

 

[EastTNHunter]

Don’t remember the exact jump, but my Savage 116 30-06 prefers ABs to be closer to the lands

 

[Charlie-NY]

FWIW - I experimented with the 165 AccuBond in a semi-custom .308. Started with bullets loaded close as you have but decided to see how far off the rifling the bullets would be if set just deeper than magazine length. Bullets set that way were .165" off the rifling. Initially I figured "no way" but decided to see what the results would be on paper. Surprisingly enough, the Accubonds loaded .165" off were the MOST accurate of any that I've tried.

Two days ago I shot some Barnes 130 TTSX that were loaded .165" off. They shot into an unbelievable 3 shot group of 1.52" and then 1.38" at 400Yyds. It pays to experiment even when your ideas may go against the conventional wisdom.

Good luck.

 

[Billyram]

My experience with Accubonds is they're not finicky to load. I seat Accubonds just like BTs .005-.010" from the lands and work up the load. The most accurate powders for the .308 behind the 150-165 gr bullet are Varget, Reloader 15 and 4895. I would work up loads with the 150gr and the 165gr. Some rifles may like one over the other. I have a 30-06 with a Broughton 11 twist barrel that is very accurate with 165gr BTs but with accubonds is slightly more accurate with the 150gr.
Billy

 

[3deers]

So.....
I went to the range with some closer-to-the-lands loads. I also took Dwh7271's suggestion, and loaded 3 at 0.080" off, and 3 at 0.100". The following are the results of 3-shot groups with the loads closer to the lands:
0.020" off = 1.18" group
0.015" off = 2.50"
0.008" off = 1.50"

From this, I am simply concluding that I should move on to the Varget powder. My 700 Remington is capable of 1" groups or less with several other hunting loads.

Then, I tried the other 2 loads.
At 80 thou off the lands, my groups continued to open, measuring 4.12".
However, at 100 thou off, I shot a 1.81" group, a significant tightening up from the 4+ inches of the 80 thou ammo.

Years ago, I never tried to draw conclusions without shooting at least four 5-shot groups.
But, before moving to another powder, I think i'll try a couple more groups, further increasing the jump to the lands, say 0.125" and 0.150".

If anyone's interested, I'll post the results, but it will be after my 2 weeks of deer hunting, as the season here opens in 1 week. I'll hafta feed the Remington 165g partitions for this year. (I'm not too worried.)

Thank you to all who have offered input.

3deers

 

[MissouriEd]

It’s my experience that Accubonds shoot better when jump is minimal. Closer is better.

 

[TackDriver284]

I would try a ladder test and see if a node can be found before going any further.

 

[Billyram]

Stick to 5 shot groups and shoot at least 2 groups. 3 shot groups when looking for accuracy can be fooling.
Billy

 

[salmonchaser]

Skimming through your report made me wonder if you had fired a control group with a known performer. Maybe something else is gunnysacked.


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[Darkhorse]

Changing your seating depth moves you toward or away from the peak of a node. Seat deeper in .010 increments. If you are approaching the peak your groups will shrink, if they open up you have passed the peak so seat a few closer to the lands by .010 increments and your groups should begin to shrink. When your groups show shrinkage start seating at .005. I would not seat by .125 or .150 increments as this could put you beyond the node and further confuse the issue.
I shoot 3 shot groups until to find my tightest groups, then shoot 5 shot groups to test it for repeatability.
Attached are a couple of examples of how changes in seating depth affects group size and location. Changes in powder charge by a few grains can also cause identical results.

 

[3deers]

Hi Darkhorse,

Thank you for your input.

I can see from your precision, and from your meticulous record-keeping, that your methods are a worthy advice. I will be trying what you suggest.

When you speak of "Peak of a Node," are you referring to the wave cycles of the barrel's vibration?

 

[Darkhorse]

Yes. And they appear regulary. That is why if you continue to seat deeper you will find another node that will give good accuracy. There will be several that might give acceptable accuracy but maybe only one that will give you that one hole group.
I have a Browning .300 Win. Mag. equipped with the BOSS. The BOSS system allows you to tune the rifle to the load by finding nodes then fine tuning for best accuracy. I personally really like the BOSS system though most don't because they failed to get the accuracy they expected. It just takes a lot of shooting and time. It took me 2 years to find a setting that gave repeatable .500 and under groups. FWIW the length of the clip restricts my seating depth and the closest I can get to the lands is .100", this really worried me in the beginning but as I found out it wasn't a big deal after all.
What I'm attempting to do with a standard rifle barrel is to find a good node by making small adjustments in powder charge and seating depth's. These small adjustments change when the bullet exists the muzzle and this gets you into different points in the oscillation of the barrel. Sort of like adjusting a BOSS in reverse.
Attached is a target where all loads were seated at .030 off the lands, but each load had a 1 grain increase in powder, it shows the same affect as changing seating depths.

 

[salmonchaser]

Last year about this time I read something similar you wrote. My .338 Jarrett was shooting well under an inch with the occasional flyer. Following your advice I shortened by .05 measured on the ogive. No more unexplained flyers, routinely punching out quarter inch groups.
Sitting in camp waiting for Saturday. It won't be the rifles fault.
Wish I had been able to purchase 1,000 250 gr AB from the same lot.


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[Darkhorse]

I'm glad I could help salmonchaser, sounds like you got it going you way.

Rereading my post it reads like I 'm saying you must seat deeper to get on a good node. I didn't mean that at all, what I meant was, since 3deers was already seating deeper my advice was to continue seating deeper until he found the next node.
Good nodes can also be found much closer to the lands it just depends on your rifle. Many rifles won't show the dramatic shifts with small adjustments that mine does, especially those with heavier contour barrels as the mass serves to help dampen the oscillations.
The rifle I was working with has the original factory 1981 barrel. I have glass bedded the receiver and the first 2 inches ahead of the recoil lug. When I find a node it seems to have a narrow window to work with.