Thread: Barrel Accuracy Nodes - How wide are yours ?

Originally Posted by sneeze

It really is a problem child that one. Magnum primer?

Not yet

Gillie, thanks for the interest. The barrel is floating other than bedded for the first inch of the reinforce, M98 action, synthetic stock, T3 brake. I try to rest the barrel between shots so I wouldn't have thought temperature had a part to play. All the shots I'd have picked as being good - within the bounds of my generally mediocre skill level anyway.

I didn't think the 2moa horizontal seemed too much for a No.2 contour but the vertical movement was unexpected. Based on the measured change in velocity (over the 5 grain variation in powder) less than 1" should be due to change in drop, the other 4moa appears to genuinely be due to barrel vibration. Perhaps then the POI could have just as easily tracked down or across. This was the reason I started the thread. I thought there would be lots of ladder data out there amongst forum member' records that they could maybe dig out & share. Next time I'm out at the range I hope to confirm by repeating the same ladder test.

Originally Posted by Puffin

Gillie, thanks for the interest. The barrel is floating other than bedded for the first inch of the reinforce, M98 action, synthetic stock, T3 brake. I try to rest the barrel between shots so I wouldn't have thought temperature had a part to play. All the shots I'd have picked as being good - within the bounds of my generally mediocre skill level anyway.

I didn't think the 2moa horizontal seemed too much for a No.2 contour but the vertical movement was unexpected. Based on the measured change in velocity (over the 5 grain variation in powder) less than 1" should be due to change in drop, the other 4moa appears to genuinely be due to barrel vibration. Perhaps then the POI could have just as easily tracked down or across. This was the reason I started the thread. I thought there would be lots of ladder data out there amongst forum member' records that they could maybe dig out & share. Next time I'm out at the range I hope to confirm by repeating the same ladder test.

Try with brake off, on a small contour tube might come would be changing the harmonics a fair amount

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Originally Posted by tui_man2

Try with brake off, on a small contour tube might come would be changing the harmonics a fair amount

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+1

Thanks, good advice.
I had it down to re-do the ladder minus the brake, expecting a complete change in pattern - mainly for interest as I quite like the brake, group size may suffer without it (me, not the rifle)

Hey Puffin,
I have just done a table from early on in load development for my 270wsm. Powder was AR2209, CCI magnum primers, 140gr Accubonds with Win once fired cases.

Weight Horizontal Vertical
54 -0.25 1.25
54.4 -0.75 0
55 -1.25 0.5
55.4 -1.125 0.75
56 0.5 0.75
56.4 -1.25 0.75
57 -0.75 1.25
57.4 -0.25 1.4
58 -0.25 1.5

Sorry I can't seem to post the scatter graph. The load "56" was left in the barrel a couple of minutes it says in my book. Not sure why but it happens when your new to it I guess. I don't use this powder in this rifle, to slow and groups were not great at all.

Rifle is a Tikka T3 Hunter, shooting from a bipod

puku

Thanks Puku. Quite a bit less movement per grain than I'm seeing. A pity your groups didn't also tighten up at the nodes and allow you to settle on a good load.

I couldn't help but notice that these loads seem very light for 2209 in a WSM in .270, 300-400ft/sec down on max.
QuickLOAD predicts pressures around the 40-45kPSI peak. This combination should be able to take up to 63-64grains for 3100-3150 ft/sec before you hit the specified maximum, and the case is still not quite full. On paper 2209 seems a good choice. Full cases of Reloader-22 or N560 perhaps wring the fastest speeds out of it at 3200 ft/sec - 66-68gr depending on how hot you want to run.
Could I ask what you ended up with as an accuracy load with the accubond ?

Originally Posted by Tussock

How many powders you tried? I had that with a 22-250, bug holes with factory Hornady ammo but nothing would get the same projectile to shoot. Switched powders, bug holes.

Been a fairly rough (read expensive) day today. All because I found a powder that did work. RL22 and AR2217 didn't (too slow?) but AR2213SC showed some real promise with a preliminary work up. Got groups down to 10mm but did not have the time to poke it a bit around to 100% validate. Decided to go and blood it on April fools day instead. The joke was on me. Broken gear and broken me.
RL17 sounds like a real performer too but there appears to be quite a price to pay in barrel life, as with most double base powders.

I re-read all the replies, did a bit more reading elsewhere, shot another ladder with the brake off ( a T2 incidentally, not T3, my typo earlier) and decided that the movement in POI was still too much and gave a fix some serious consideration. I had the barrel re-headspaced, discarded all my Remington brass, then fireformed a new batch from Norma. The ladder with the new improved brass ( 62gr through to 67gr of Reloader- 25 ) was recorded at 200 metres and covered half the spread observed with the old brass; 1moa wide, 2.5moa of vertical.

The excessive spread previously was due to the tired brass.

So that's interesting, and a +1 for the general rule of engaging the grey matter to assess the available data before wasting a whole lot more consumables at the range. I still need to select a node to work with.

As an aside, the groups with the brake off were twice the size as with it fitted, and just confirms the detrimental effect recoil can have on accuracy when shooting with very average ability - even with mid-calibres. Greg's design gets a big thumbs up from me, one of the better investments in gear I've made...$400 (inc. fitting) to halve average group size, so highly recommended.

Hi Puffin,
I stayed well away from that 2209 for the wsm. In a 270win it works well and with ok speed. I am using Ar2213sc behind the accubonds, but am working on a load with 150 VLD's. I ladder tested tham last Friday. Done with 2213sc and 2209 in Fed Brass. I'll find a pic (Running late but the lambs won't get shorn till I get there so now biggy).



So from my range book I can tell you;
Range 100 yards.
150 gn Berger VLD
FC brass
CCI 250 primer
OAL 2.800"

The above info is correct for both ladders. The below powder was the lower right hand 'group', aiming point was centre of target.
AR2213sc in weights 58.5,59,59.5,60,60.5,61,61.5,62 gn.

First hit was low, then into the group, until last two rounds pushed out to the right.


'Second ladder'

AR2209 powder in weights; 64,65,66,66.5,67,67.5,68 gn. This was aimed at the top left corner of the box, wind came up when I started shooting.

1st 1 5/8" low, 1 1/4" left
2nd 1/8" low, 1/8" right
3rd 1/4" low, 1/2" right
4th 3/4" low, 5/8" right
5th 1/4" low, 1 3/8" right
6th 5/8" low, 1 5/8" right
7th 1/4" low, 1 5/8" right

So with the 2213sc the 'node' is effectively 2 grains wide??

PS I haven't put the hit measurements in as its pretty self explanatory.
Also I was going to start a new thread but people are less likely going to mock my shooting if I hide it here
Puku

The AR2213sc result looks REALLY good Puku. I think that is correct in that the node is very broad - which is a great result to get early on. Within this range there is presumably an accuracy optimum that could be identified by shooting groups at 59.5, 60.0, and 60.5gn. If you have the resources maybe the two outside loads at 59gr and 61gr are worthwhile.
In my limited experience with Berger VLDs (in 7mm and .257) the seating depth seemed to be the parameter to nail down first. I couldn't get any decent groups with changes in powder with the depth not optimised. However to get the kind of cluster you already have over a 2gr variation in powder you must either be close to the right depth already or have a barrel that isn't fussy. Either way the early signs are that you've got a tackdriver. I'm very envious.

Yes these are seated 0.010" from the lands and fit into the mag. Earlier on I had used another depth which I can't remember at present but the clusterings were not as tight as here. So from reading other people's reports I decided to restart the load development. I.E. start 0.010" from the lands, find your powder weight where pressure is felt and number one accuracy is good. Then adjust seating depth to find the 'spot' for THE rifle.

Considering that this is a tikka T3 Hunter and its shooting like this with VLD's that fit the mag I'm stoked. As it was going to be fix/adjust the magazine.

Far out 5mm groups. I could only wish of being able to do that.
Tussock do you notice change in group size at maybe 300m? I am wondering because in my theory won't groups grow vertically with higher ES figures.

On a different note the 150gn burgers seem to be pushed right with more pressure (I don't think I said in the earlier post that the last shot of ar2213sc had pressure signs). But with the 140gn accubonds the projectile gets pushed vertically with higher pressure.


Please note this is not scientific but just my observations while at the range. I should also say that the indicator of high pressure I see in this rifle is a sticky bolt lift. No case marks, and only slight primer flattening.

Puku

Tussock, could I ask what powder you are using that has allowed fine tuning to the centre of a 0.5gr wide node and then maintains that level of accuracy with temperature variation ? 2213sc / H4831sc ? I don't think the RE-25 I'm using would work with a node that narrow - and the nodes in the .280 here are shaping up as being that narrow - so I'm looking for something a bit more stable to swap over to.