340 Wby load results questions

[tdbru]

Last time out i ran a pressure series and determined what my max load was.  using 185gr. Barnes TTSX (it is as long as a speer 250gr. grand slam for those of you who think it's too small for the 340) with IMR4451 and GM215M.   i tried 86, 88, 90, and 92 and found that 90 was max.  but none of the groups were anything to write home about. 

today i did a short, finer grained ladder.  89, 89.5, and 90.  89.5 and 90 were again nothing to write home about.  but the 89gr. group shrank considerably. 

have any of you experienced this, where such a small powder amount variation results in significant change in group size?  i am suspecting it's due to barrel harmonics.

my 340 is an early Japan model.  26" bbl.  if i recall the advertising back then was a 1.5" three shot group at 100 yards with premium ammo.

i put a Leupold 6x42 on it with Richard Near's one piece ring/mount. (attached if adding the photos worked.)

this was at 207 yards (our 200 yard range is a bit longer than spec) off the bench with the rifle forearm held in my hand which is on top of the front bag.  as you can see the 89.5 and 90 are not too good.  the 86, and 88 looked a lot like the 89.5 group.  but the 89gr. group shrank considerably.  so that will be my load with this bullet.

the 89.5 had the lowest SD but all three (89, 89.5, and 90) had reasonably low SDs.

89 -> 3368 fps avg.  SD= 11 fps.
89.5 -> 3408 fps avg.  SD=7 fps
90 -> 3422 fps avg.  SD = 10 fps.

any way, due to the barrel harmonics in this stock, the way it's bedded, etc. i will go with the 89gr. load.  but i've not seen this kind of group change with such a small change in powder.  do other weatherby MkV exhibit the same thing?

thanks,
-tdbru

[tdbru]

p.s.  if you're curious the extreme spread on the 89 was 1 7/8" .  i.e. sub-MOA
-tdbru

[Northern hunter]

If your not stuck on using 4451, give 7828 a try got real good results with my Japanese built 340 using 225 Hornady sp, punching through 1" plate steel at 300 yds.

[GrandeJuan]

I use RL22, 86 gr, Fed 215M primers and 250 gr Nosler Partitions and get 1.0 groups at 100 yds and 1.5 inch at 200. Mine does have a Douglas Premium barrel. Hope this is useful. GJ

[tdbru]

thanks guys for the other load suggestions.  i guess i didn't make my question clear.

i noticed on my rifle, there was a very small window of charge weight (<1% change) where the rifle went from grouping mediocre to great. 

have any of you who handload for your weatherby MkV rifles noticed the same kind of behavior where there is a very small window of powder charge weight for great accuracy?
thanks,
tdbru

[224KING]

Yes.It has happened to me with a very hard to load for 240 Weatherby magnum.I've omly experienced that sort of thing with that one 240.Sold it 25 years ago.That rifle gave me plenty of fits.The only thing that it would decently shoot was the Factory 100 grain SP.I shot several deer with thatr rifle out to 600 yards.I loved hunting those 800 and 900 acre wheat fields.

[.257]

Yes this is normal. Did you check what 88.5 does?
I have a 6.5-284 that l worked a load up with. Just under 50 rounds with one bullet and one powder. It now shoots just over .5 at 100 yards and well under 10 inches at 1000. The smallest change can make a difference.

[tdbru]

thanks.  good to know that this is normal.

i haven't tried  88.5..... yet.  it's on my list.

i guess the solution is to just not give up.  but on weatherby cartridges, since they tend to be loaded to max pressures and are, in general, considered "overbore" when do you say uncle before the bore is toast and you need to re-tube?  some of the calibers have a reported accurate life under 1500 rounds.  of course for big game hunting alone, barrel life is not an issue.  but for load development with, say 5 powders and 10  bullet types/weights,  if you have to go by 1/2 grain increments,  i am thinking you could probably use up a barrel just finding the perfect load.  get the rifle re-tubed, and start again.....  of course with all that range time you'll likely be a great shot when it's over, so nothing goes to waste.

i'll give 88.5 a try and i am thankful for the forum's help.  also happy to find a reasonable load "fairly" fast.  reason i like 4451 is it has 4350 burning rate.  Hodgdon says it sits right in between IMR4350 and H4350, which works well for a 185 gr. bullet, and since the pure copper bullets have a reputation of being bore foulers, especially at the velocities that Weatherby cartridges are capable of, the copper removing agent is a great bonus.  and the temperature independence is also important. 

this being an older MkV the barrel is not as smooth as new ones.  it's a little "raspy" in there. barrel boring cross axis marks are evident.  it doesn't appear to have been post bore lapped.  yet, with 4451 there is such minimal amount of copper fouling that 1 or at most 2 patches of Barnes CR10 is all it takes to get the copper out of the barrel.  and with SDs in the single to just double digits, that speaks well of it's temperature consistency i think. 

back to the original question.... do any of you do load development and ladder tests in less than 0.5gr. increments and if so, how much group reduction are you seeing??  i.e.  if i hit "sub MOA" do i just call it good and go hunting and save barrel life for that or continue to fine tune and see it go from just sub MOA to under 1/2 MOA??  does the additional testing give good ROI to reducing group sizes even further.  i realize each rifle is unique so there is no way to predict, but just curious about the forums experience to really fine tuning charge weights.
thanks,
-tdbru

[224KING]

Really depends on the case capacity for me.If it holds a lot of powder I don't get down to the nut cutting until I get something that has promise.Then I start going in halves maybe.On cases like 222 Rem I work in 10ths of a grain at times.

[tdbru]

got back out to the range.

88.5gr. of 4451 gave 3358fps avg with sd of 19fps.

did have 3 holes touching,  others were scattered into about a 2MOA group overall.

tried 89 again.  seems to be the magic load as far as consistency goes.  3375 fps with sd of 6fps.   again.  very low sd.

i had 2 holes touching at 89 and about 1.5 MOA. 

since i had 2 holes touching, and 3 holes touching,  i'll say the scatter was my poor bench technique with this rifle.

this at 207 yards.  scope is 6x.  but no mirage to fight so the scatter is me.

then i shot some in sitting position at a gong at 294 yards.  hit it 3 out of 5 shots.  flinched the other two. 

so i have some learning and practice yet to do.  but i think i found the combination for this rifle with this bullet and powder. 

now i just have to learn to shoot this well from various field positions.  if i can't, then all the extra range available is wasted.  So i think the  load and bullet are up to taking game to 500 yards from the point of enough remaining velocity to get good bullet expansion.  just my Marksmanship, right now, it not commensurate.  time to do some more loading and practice.

88.5gr. of 4451 might prove as accurate at 207 yards as 89gr. but i think the very low velocity variation at 89gr. will be more conducive to precision at longer ranges, which i'll have to practice to see if that's true.
thanks WN for the support
-tdbru

[BB340]

Yep sounds like your .340 is on song and now all that is needed is for you to get in tune with it. Once you do that there will be no stopping you. Best of luck and look forward to hearing of future adventures of you and your .340.