Vertical stringing driving me nuts

[Nocalphoenix]

Rem 700 in .308, mcmillan stock, Falcon scope. All screws are tight and Federal 168 match runs under 1/2 moa. Im using Berger 155.5 over various loads of varget in Federal once fired cases and Federal primers. So far the loads are very consistent, horizontal is about 1/4 to 1/2 moa at most with about 1moa or slightly over of vertical. In the past the simple solution would be a primer or powder switch but with component availablilty that is out of the question. I stopped at 46.5grs of varget at 2.850" OAL with no signs of pressure. Should I bump it up a little more and see if I can get the vertical to settle down? The top load is about 2915fps with an es of 15 for 5 shots. First photo is 46.0, second is 46.3, third is 46.5, last is four rounds of Federal match in one ragged hole.

 

[BOLTRIPPER]

Re: Vertical stringing driving me nuts

too much coffee

 

[BOLTRIPPER]

Re: Vertical stringing driving me nuts

my 155 amax uses 45 grns...and i can stack the holes


fix'em to 2.80.....

 

[Lowlight]

Re: Vertical stringing driving me nuts

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body">too much coffee</div></div>

Bite your tongue there is no such thing.

 

[Wetworker]

Re: Vertical stringing driving me nuts

How long are you waiting between shots? Just a thought. I had a similar problem a while back and waiting until the barrel cooled down made a difference. Later I changed the load and I think I got it closer to a "node", and now I get less variation even when the shots are rapid follow up.
Again, it only seemed to happen with that one load.

 

[CoCaDoRi]

Re: Vertical stringing driving me nuts

even your fed match has vertical in it.

How do you check seating depth?

Do you have run out?

Which is your first shot? Which is your last?

Bergers typically don't' like to jump.

 

[81sfo]

Re: Vertical stringing driving me nuts

Is your stock bedded?Is the barrel free floating all in the barrel channel?Looks like your close to the load ,try 46.7 if you see no funky pressure signs.

 

[CoCaDoRi]

Re: Vertical stringing driving me nuts

Have you done a round robin load work up? This pretty much will tell you where your stick likes it.

 

[Victor N TN]

Re: Vertical stringing driving me nuts

Often benchrest shooters either cut back a small amout on the powder or increase it. Usually vertical stringing is caused by catching the round leaving the muzzle in the middle of a "node".

Try varying the powder half a grain or less. You may end up being .2 or .4 grains off your best load. It may be a larger amount. But make the changes small to start with.

 

[CoCaDoRi]

Re: Vertical stringing driving me nuts

Good Point Victor.

You need to go .5 gr increments. .2 or .3 is fine tuning. It won't tell you much at this point.

I still think you need to go back and do a round robin. I bet you are between 45-46 grs in the end.

 

[Wil]

Re: Vertical stringing driving me nuts

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Weda'</div><div class="ubbcode-body">Bergers typically don't' like to jump. </div></div>

The Berger's are nearly identical to the Lapua 155 Scenar... They will tolerate quite a bit of jump if the charge weight is right...

shoot a ladder test... find out where the max is in YOUR rifle & back it down...

Work backwards in .2-.3gr increments until you find the node...

 

[427Cobra]

Re: Vertical stringing driving me nuts

http://www.6mmbr.com/verticaltips.html

 

[CoCaDoRi]

Re: Vertical stringing driving me nuts

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
The Berger's are nearly identical to the Lapua 155 Scenar</div></div>

errr..nope

Ladder tests are ok... the round robin will tell you exactly where it wants to be for that powder, bullet, primer combo. Then you can fine tune.

 

[Wil]

Re: Vertical stringing driving me nuts

ok...not exactly... but they are very similar... and also tolerate jump... at least in my rifle they do.

both tests will yield good results

 

[CoCaDoRi]

Re: Vertical stringing driving me nuts

I've shot a lot of bergers. Spoke to people about berger a bunch.

My results have always been best to touch or in a bit.

Hey I'm sure some have had good results with jumping them. In the BR circles where a ton of bergers are shot you'll see the overwhelming majority will say touch or in a bit.

The ladder test is good, don't get me wrong. the round robin will show you the node or nodes without question.

 

[Nocalphoenix]

Re: Vertical stringing driving me nuts

Thanks for all the comments. Im using a redding bushing die with a .338 which puts me a .002 tension, seater is a forster and runout is less than .003 for all rounds shot. Stock is bedded in devcon with the holland pillar so the floor plate is floating.

I forgot to add this was done round robin with the exception of the Federal match. On the federal group is it only four rounds but three are in the top hole with the last round being the low left. Weather was excellent, about 60degrees with wind from the tail at less than 3-5mph.

I went with the 155.5 over the other bergers because Eric recommended it for magazine feed due to it being less sensitive for OAL. I have also heard these have a sweet spot in the 2950fps range. I will try the last two loads and bump it up a little and see what I get.

 

[Victor N TN]

Re: Vertical stringing driving me nuts

I do a lot of Bergers myself.

 

[CoCaDoRi]

Re: Vertical stringing driving me nuts

Why bump it up when your first group at 46 is the tightest. The more you increased the taller it got.

Try more neck tension.

 

[Nocalphoenix]

Re: Vertical stringing driving me nuts

Well I only had time for two groups and the were identical, nice round ones with no signs of vertical running 46.7grs. Still no pressure signs and I did not have my chrono up. I only grabbed one photo and the other target stayed on the stand for the evening. I always thought someone lighting up a braked .50 on the next bench would at least have the courtesy to let you know its coming, hence the bad flinch to the left....and of course it was the last shot.

 

[Victor N TN]

Re: Vertical stringing driving me nuts

You got rid of most of the vertical though...

I hate to say this. Because a lot here will take it the wrong way. But MORE POWDER isn't ALWAYS the answer. This time it worked. But other times I have decreased it and it worked very well.

 

[CoCaDoRi]

Re: Vertical stringing driving me nuts

Ok so the vertical isn't there. But what did you do different?

 

[skeetlee]

Re: Vertical stringing driving me nuts

I had this problem a while back and what i come to realise was that i wasn't mounting the rifle with the same cheek pressure every time. The different pressures on the stock created different harmonic variations. Lee

 

[Nocalphoenix]

Re: Vertical stringing driving me nuts

The only thing that knowingly changed was bumping the powder charge up a bit. I ran the same bipod and rear bag, gave up caffine and the weather was beautiful, pretty much dead calm conditions. I also concluded Im doing real well on follow through, I did not have the mag seated all the way and dropped the trigger on an empty trigger. I have to say it was the most satisfying shot I have let go in a while, did not see the crosshairs move even a tiny bit.

Thanks for the help and suggestions. I will reshoot the last load and confirm it was not a fluke but when the targets were overlapped they measured .52 for 9 shots so I feel pretty good. I will run it out to 300 tomorrow and I will know for sure.