Home Forums Hunting & Shooting Hunter's Campfire Bullets Pushing Left

Good evening campfire, wondering if someone might be able to explain something to me. I have been developing a load for my .260 with 140gr Berger VLDs over RE17. It is a Savage 12 action, bedded in an all aluminum chassis with a shilen barrel, and shot from sandbags dug in front and rear. My sweet spot is 41gr on the dot for the tightest group, but the best leniency is 41.41.9gr. Here is the kicker though... as I'm pushing more powder, my group are staying relatively consist vertically but pushing about a 1/2" right with less powder and 1/2" left with more powder. Then at 42.5 it centers back up, just as it did with 41. Anyone got an opinion on this phenomenon?

Barrel harmonics. Bullet leaving the barrel at a different point of the barrels arc

I've seen that cause stringing up and down, but this is literally just moving the center of the groups a little left and a little right. Just not something I'm used to seing swing back and forth. Usualy they continue to push in the same direction as a powder charge increases.

It's built on a Savage so the POI will always shift whenever you change anything.

Welcome to the 'fire.



Travis

LMAO, Thanks for the welcome buddy. Been a long time watchin posts, never felt a need to make one for myself till now.

Nuke, you seem to make the assumption that harmonic vibration in barrels are only active in one axis. That is not the case. Receiver cut outs contribute to such hysteria. Bedding does as well.

Makes sense, just not something I've seen before. Usually they don't come back to center and past. Maybe I'm just finding the center of a left right node

Welcome !

...have you asked Mr. Berger about this ?

Some of the new, LONG VLDs are defying some long established, and carved in stone "rules" of behavior.

love the 41.41.9 data, but would suggest that for safety's sake you drop down to 41.41.5.

GTC

Roger that on the backing down, I've tested up to 44.5gr before I started getting pressure signs, but I much prefer the gentle nature of the lighter loads. The 41gr gets me an average of 2785fps measured with a magneetospeed and that held the tightest groups for me but it's a bit sensitive and opens up with .02 less/more of charge and I'm suspecting that's due to the pressure curve. It also had the smallest ES of only 5fps as long as I keep it at 41gr on the dot. The middle of the road load at 41.9 has significantly more thump on the shoulder and an ES of 24fps with a velocity avg of 2836. Another unique spot in the load range is between 40.3 and 40.8, pretty much everything in between this range gives me 2740-2741 avg fps. Which is great but the ES is up to 30fps. The groups aren't tiny, but they hold about vert just under 1" and .5" laterally. My worry was them being a little on the slow side for anything past 600.

All guns have their own personalities. I have a Swede that is so finicky that it to took me a couple of years,a few pounds of powder,lead,and copper to finally get it to shoot like I thought it should.
Some guns just take more attention and tinkering than others do.

Spot on with that assessment, it's all for [bleep] and giggles. That little 41gr load serves me well, but I still play around every couple weeks trying to eek out a little more consistency. I wish I'd had a chrono when I did the pressure testing just to see what the velocity looked like on the high side. On the lower side there was a honey hole at 39-39.5 that made good groups but only reached 2650fps.

Funny thing, like Crossfireoops mentioned about contacting Mr. Berger. From reading up on these Berger VLDs it is interesting in that they seem to have different flight characteristics downrange when launched at different velocity windows. Certainly due to stabilizing effect. But no one ever comes outright and says, "we've tested everything and for this XXXmodel/XXXweight bullet we get best flight at XXX range results at XXX velocity.

Probably what keeps most of us playing this sadistic game, is just how complicated the variables can be. Even something as modest as 5lbs more/less torque to an action screw will change the flight path or grouping. Pretty amazing fingerprint for mechanical engineering when you get all the parts flying in close formation.

Spot on with that assessment, it's all for [bleep] and giggles. That little 41gr load serves me well, but I still play around every couple weeks trying to eek out a little more consistency. I wish I'd had a chrono when I did the pressure testing just to see what the velocity looked like on the high side. On the lower side there was a honey hole at 39-39.5 that made good groups but only reached 2650fps.

Funny thing, like Crossfireoops mentioned about contacting Mr. Berger. From reading up on these Berger VLDs it is interesting in that they seem to have different flight characteristics downrange when launched at different velocity windows. Certainly due to stabilizing effect. But no one ever comes outright and says, "we've tested everything and for this XXXmodel/XXXweight bullet we get best flight at XXX range results at XXX velocity.

Probably what keeps most of us playing this sadistic game, is just how complicated the variables can be. Even something as modest as 5lbs more/less torque to an action screw will change the flight path or grouping. Pretty amazing fingerprint for mechanical engineering when you get all the parts flying in close formation.

I would play with seating depth to get the bullet to leave at the top of the harmonic.

1/2"?

Load a bunch up and go kill schit with them.

Welcome to the fire.

fixed it...grin

Hell...I thought they all did that.

thats why your scope is adjustable. no 2 guns act the same.

x100

Ditto on the action screw torque having a dramatic effect on the groups plunking in tight or loose, here or there. My rifles are built on the Savage Target Actions, either right bolt-right port or the dual port right bolt configuration. All shoot best with 35 in-lbs front and middle screw, 30 in-lbs rear screw.

Stocks are laminated varmint style pillar bedded with only the action epoxy bedded. Barrels, barrel nut, recoil lugs and rear tang are free floated.

The Shilen barrels I have are accurate, but one is scrap, because the twist is too slow - my fault. Pac-Nor and Brux (if you can get them), and Hart Barrels are less prone to weirdness. All barrels are Savage varmint contour.

Faster twists are in order on all my rifles, as I'm shooting lead-free. Even when using some manufacturer's recommend minimum twist I have had problems with stability and load sensitivity. In one case the 6mm Barnes Varmint Grenade loaded into a 1:14" twist wouldn't stabilize to the point it completely missed a 100 yard target. When I finally had one hit it was completely sideways. Switching to a 1:10" twist recommended by Barnes, it shot around 1.5" groups. Then I tried a 1:8" twist and groups shrunk from .18" to .30" depending on load.

Berger recommends 1:8" twist for the 6.5mm 140 grain VLD bullets, so if you're using a 1:9" "standard twist" that could be all or part of the problem.

Three areas to watch on Savages generally are the recoil lug seat, the front scope base screw clearance and the rear tang free float. Some of the following may or may not apply to the Model 12 action, but is a good starting point. You probably already know all this, but I'll stick it in for other readers, and in the interest of being an insomniac and trying to help.

Watch the locator pin on precision recoil lugs, and check the stamped OEM lug as well, if the locator pin touches the action at the bottom of the relief cut, the lug isn't seating against the action face. The lug locator pin needs to be cut back slightly or a lug with a ball tip pin needs to be installed. That stamped OEM lug needs replacing with a precision lug.



Flat OEM pin vs ball faced pin (Sharp Shooter Supply) recoil lug.



Front scope base screws included with most bases are too long and if not fitted will bottom out against the barrel threads, placing tension on the barrel and ding up the threads, leaving the front of the base loose. If the base is too long it may interfere with the recoil lug as below.



Here the screw has been shortened so it is below the barrel threads and the base has been dressed back a few thousandths behind the action face. Not all brands of bases will be too long, but the screws will still need checking.



Below are the areas that should never touch the stock inlet, even an aluminum chassis. Here the area has been masked with PVC pipe wrap and electrical tape prior to epoxy bedding. Only the rear of the recoil lug should contact the stock mortise. This also applies to my Remington 700 builds using a Savage type barrel nut and precision recoil lug in aluminum chassis stocks. P.S.: I still run the clearances and skim bed the chassis with epoxy on them all.



Most Savages shoot best with the rear tang free floated. The action below has been glass bedded with the tang clear of contact.



I also torque the barrel nut to 40 ft-lbs, with all threads - receiver, barrel shank and nut lightly coated with Pure White Teflon food grade anti-seize lubricant. http://www.amazon.com/WHITE-31003-G...r=1-1&keywords=Pure+White+anti-seize

If all this stuff checks out, then you have gremlins, or that's just the way things are.

Wrangler John,
Thanks for the insight. You're right on just about all of that. First thing scrutinized in the build was the recoil lug. It's true and it's ball pointed. One thing that I haven't done was to glass the V-block. Might get around to doing that down the road but I've been trying to see what I could wring out of it in the raw. I checked clearances by chalking the action and bedding block. The clearances are full contact on both sides of the reciever from the rear action screw to the front of the action. Around the recoil lug and barrel nut there is a bit of material removed to provide ample clearance. The rear tang touches but isn't planted into the stock and has the slightest of clearance just under it. That might be floated a little better if I bed the action or even if I run a little less torque on the rear action screw. Once the ammo is dialed in, that'll probably be my next tuning procedure (mapping out the torque effect on the action screws).

I know I tend to way over-think/analyse/work all of this, but on the weeks where I can't get out and play at longer distances it serves as a keep me out of trouble pass-time.

I appreciate all the feedback from you guys. Even the non-savage lovers. After all, we all go fanatic over something or we wouldn't be here!