Bullet stabilization problem ?

[ecomeat]

I am a newbie, and have only been shooting F Class for a year, using a BAT actioned 6 x 47 Lapua in F Open but have started to notice an issue with erratic performance at 300 yards.
I am shooting 105 gn Berger VLD's, and now 105 gn Hybrids, at 2975 fps out of a 30 inch, 1 in 8 twist Krieger SS barrel
I am consistently shooting 58's to 60's at 400 yds to 800 yds but only 56's and 57's at 300 yds.
Last weekend would be a classic example: 57.0 at 300 yds, 60.7 at 500 yds
"Could" it be an issue with stabilization of bullets that are undoubtedly designed for long range performance ?
Has anyone else ever had a similar issue ? Or is it just "me" ?
I am extremely conscious of doing my best re consistency in every aspect of releasing each shot.....grip, breathing, trigger squeeze etc etc. Am using a 5-50 power March scope to no excuses re sight picture.......just the frustration of dropping 3-4 points where I should be nailing x's all day.
Any thoughts ??
Ecomeat

[Barry Davies]

Try reducing your MV by 100 f/s
Barry

[AlanF]

Ecomeat,

It does appear that your loads are not tuned for 300, but somewhere further out. I would try some ladder testing at 300. Normally I ladder test at 500 because you get a bigger range of elevation to analyse, but in your case, with poor accuracy at 300, you could get enough elevation variation to see some patterns. If you don't know what ladder testing is, Google it - there's a few explanations of the method around the web.

With your 6 x 47, I would do powder increments of 0.1 gn over about a 2 gn range i.e. 20 shots. Best to use a chrono during the testing and use the velocity information in the analysis. Do some preliminary testing to get a rough idea of what powder charge range to use. Your current velocity of 2975 is quite conservative for the 6 x 47. I have heard some figures of 3200 fps, but am not recommending anything like that. But I wouldn't drop it down as far as Barry suggests - that's 6BR territory. At the Vic Queens, Wilf Wright was running his 6BR at 3000 fps , and it didn't do him any harm (3 possibles on day 1).

P.S. There's another quite different possibility for your poor accuracy at 300. At OPMs at least, 300 is often the first range. Could it be that your barrel needs about 10 shots after cleaning before it settles? Probably better to test this before all the trouble of ladder testing. Try shooting say 500 first, then 300.

Let us know how it goes.

Alan

[ecomeat]

Thank you both for the input. I appreciate you taking the time to help out.
Alan, think I will go your way first, and go straight to your suggestion of ladder testing. I am pretty confident that I can rule out a potential barrel fouling issue, "post cleaning" . My first one or two shots will be slightly low , and mostly its just the first, and then I am right on target. I clean thoroughly at the end of every days shoot, regardless of wether its been 22-24 shots on a club day, or 30 plus on a bigger day. Once the first fouling shot is fired I am generally 99.9% sure that the next one will go exactly where i aim it.
On that point, I certainly DID have trouble getting all of the copper out of the barrel when it was brand new. I broke it in very carefully, and at the 30 round point, I bought a borescope back from the US and was quite shocked at the copper streaking in a barrel that should have been squeaky clean.
JB paste used every cleaning (every 25 to 30 shots) certainly got it cleaned but I was very uncomfortable using an abrasive product like thati every time.
Then at about 250 rounds fired mark, I discovered Bore Tech Eliminator and have used nothing else since. If I follow their recommended procedure twice,
it is perfectly clean of copper every time.....and I do use the Hawkeye to check, every single time I clean. Total round count is now approx 660.
As I said, after my first fouling shot which is always a fraction low,I am pretty confident that the subsequent shots will all go exactly where I aim
them.
Ladder testing here I come !
NB I do weigh and batch the Berger projectiles, have neck turned my very even weight Lapua brass, check weigh every single powder charge, and hand seat primers with a Sinclair priming tool. I use a Wilson neck die for de-capping, and Wilson Seater with micrometer top, and after 4-5 firings with my (relatively) mild loads, I haven't even had to think about FLS , as
all cases are still chambering and extracting very easily and primers are fine.

[Norm]

Ecomeat,
Have you considered parallax?

300 yards can be a distance where parallax will be at its worst. At 500 yards and beyond, your parallax adjustment will be further towards its maximum travel and any error in your reticle/parrallax adjustment will be minimised.

Do you use prescription glasses?

[ecomeat]

Ecomeat,
Have you considered parallax?

300 yards can be a distance where parallax will be at its worst. At 500 yards and beyond, your parallax adjustment will be further towards its maximum travel and any error in your reticle/parrallax adjustment will be minimised.

Do you use prescription glasses?

Norm,
Damn good point ! No I hadn't even considered parallax !
I dont wear any glasses, but you know I never gave parallax a seconds thought. Thank you for bringing it to my attention.
It will go straight to the top of my "preparation Must Do List" and even before I do Alans Ladder test.
God, I hope my answer is that simple !!
Ecomeat

[Cameron Mc]

If not parallex I would go with Alan's idea. Could be the clean barrel. I know you have done your homework with preparation and cleaning. Remember seeing you shoot 60.8 at 500.

I would shoot a clean barrel at 500 and then go to 300.

Cameron