vertical stringing

[mainiac]

Been working with a new to me marlin 336,in 30-30. Old waffle top,with 24 inch barrell.
Having problems with bad extreme spread figures,which is another story....

What is the story is this,,,,,
This rifle will throw a shot an inch high on average,for each shot above 60 f.p.s.Will do the same thing with low velocity shots,except the other way,which would be down.So what im saying is that an E.S. of 120 f.p.s.,will give me 2 inches of vertical dispersion.200 f.p.s. e.s.,will easily string 3 inches.

Ive fired many thousands of rounds,and played with the chronograph for years,and i used to figure that e.s. didnt really mean that much,until i ran into this critter.

Have any of you guys ever run into a rifle like this? It also changes poi,with very small increase/decrease of powder charge.Like,between 1300f.p.s.,and 2100 f.p.s.,it will be 7-8 inches btween these points.Never had a gun so load sensitive,and was wondering if you guys have ever run into a rifle like this one acts?

In the mean time,i have to get these e.s. numbers down,so this vertical sillyness,will go away.Aint figured out yet,why its doing it.Happens with 6 different powders,from mild to wild.

[geargnasher]

Vertical stringing and bad ES figures are often the same story.

Are you shooting cast boolits? If so, what kind of lube are you using?

Gear

[btroj]

First the obvious- don't shoot loads with wide extreme spreads.
To me it would be a frustration but not a big deal. It is a 30-30 leveracrion. If it shoots 2 inch groups at 100 yards I would be quite pleased.

Get the book "Accurizing the Factory Rifle" by McPherson. Look at what he does with the magazine tune and per things to reduce vibration induced problems. You might also bed the rear of the receiver with the buttstock- he claims that alone can reduce vertical flyers.

So many things can cause this. Easiest to me is finding loads with small ES. Might take some effort to do but it is something totally in your control.

[montana_charlie]

Ive fired many thousands of rounds,and played with the chronograph for years,and i used to figure that e.s. didnt really mean that much,until i ran into this critter.
Seems that you have the problem identified.
Now, you have to decide how to cure it.

I would start with the brass preparation, and go from there.

CM

[caseyboy]

What powder/charge are you using, and how are you measuring it?

[mainiac]

Vertical stringing and bad ES figures are often the same story.

Are you shooting cast boolits? If so, what kind of lube are you using?

Gear

shoot cast exclusively.Been shooting the lee 310170,and now the 312185.This gun has a .310 groove,so im hesatent to buy my prefered rcbs molds,fearing that they/it will cast small.

Shoot felix lube,never seen a need to change.I have many other rifles,and havent had any problem getting them to shoot nice small groups,but this rascal is really trying me.

In most all of my past shooting,a 100f.p.s. es hasnt meant much to me,,the groups would be small.But this thing is a different animal. If the chronograph registers a high shot,i dont even need to look at the target to know that shot went high,its that repeatable.

[mainiac]

Seems that you have the problem identified.
Now, you have to decide how to cure it.

I would start with the brass preparation, and go from there.

CM

ive been using a expander die from a 32-20 set,after the f/l sizer.This gives a pretty light boolit seat pressure.The next loads i try,im going to go to a harder seating pressure.

Mag primers dont help
crimping dont seem to help either
the powders im using dont behave this way,in other guns i shoot.
Cases are trimmed,and sorted

So you see, im really hoping that increased boolit pull,will help me,cause im running out of options......

[cbrick]

Could help a lot if we knew what the load is.

It's possible that something as simple as a primer change could help with vertical stringing but without more info to go on . . . ?

Rick

[mainiac]

Could help a lot if we knew what the load is.

It's possible that something as simple as a primer change could help with vertical stringing but without more info to go on . . . ?

Rick

Ive got to many loads to list.They all do it,so i dont think its powder specific.I mostly shoot wlr primers,though. Tried a primer test,and didnt see any conclusive results.Mag primers definatly didnt do what i hoped they would.

On the bright side though,i found a load in an old speer book last night,that used 4831 powder.I have a bunch of aa-3100,which is pretty near the same.I loaded that with the 312185 boolit,and shot a .550 group@50 yards,1840 f.p.s.av,with a 22 E.S. spread.Thats a case full of powder,so 1900 is probaly the limit with this powder,but if i can repeat this grouping ability,,ill be happy....

[geargnasher]

OK, what about powder position in the case? Have you tried a small tuft of Dacron with your other powders to keep it located in the case? It seems that the "case full of powder" (AA 3100) and excellent results from that should tell you a whole lot right there.

Gear

[44man]

I too think it is the powder used. I tried 4198 in my 45-70 and it would jump from 1600 to 1800 fps and stick brass.
3100 is a very slow powder but is a good powder.
I would try Varget next. Super good stuff.

[mainiac]

OK, what about powder position in the case? Have you tried a small tuft of Dacron with your other powders to keep it located in the case? It seems that the "case full of powder" (AA 3100) and excellent results from that should tell you a whole lot right there.

Gear

Ive often thought about filler,exspecially with my 4227 loads,but ive heard all kinds of srories about ringed barrells and stuff like that,so ive never tried fillers.I really have a suspition that it may be powder position giving me fits.Ive shot alot of h335 loads,and even max loads leave space in the case,although this powder hasnt bothered me in other rifles,maybe it is in this cantankerous thing!

[mainiac]

I too think it is the powder used. I tried 4198 in my 45-70 and it would jump from 1600 to 1800 fps and stick brass.
3100 is a very slow powder but is a good powder.
I would try Varget next. Super good stuff.

dont have any varget here,but i do have alot of v-133 powder left over from my old br days.Gonna try that powder for tommorrow.Have v-130 as well,so ill try that as well.

[303Guy]

Check the magazine. I have a tubular mag 22rf and one day I decided to glue the magzine into the barrel ring. Accuracy went south big way. Removed the epoxy and things were good again. But it sounds more like stock bedding to me.

[ku4hx]

The only time this was a real problem for me was when it was caused by uneven barrel support in a bolt gun. As the barrel heated it actually deformed slightly where the stock impinged on it. Full floated the barrel and vertical stringing went away.

May not can do that sort of thing on a lever gun.

[runfiverun]

using the 4227 and getting the gun hot will do it all by itself.
you are getting into the light load fast rifle powder scenario here and a filler will most definately help.
i done a test with 322 [posted here] a while back with and without fillers in three different bbl lengths in 7.65 argie.
the velocity variations went from 150 fps average down to @12.
strangely my oldest girls 7.7 will throw the fast ones low...
you need to go to either a faster non position sensitive powder, or a more case filling slower powder.

[mpmarty]

IMHO vertical stringing can almost always be correlated to the time the boolit spends in the barrel. Shorter dwell time lower poi. This seems to be because the rifle is recoiling as the boolit travels the length of the barrel and is thus launched on different angles.

[44man]

All of you should have seen my posts about 4227 in the .44 mag. Gun heat would string shots so much that I was 16 clicks over normal at 200 meters yet still hit 50 meters short for the last ram.
It works fine in some calibers but can drive you nuts in others.
I never got it to shoot in the 45-70. But it is gold in the .357 max.

[Larry Gibson]

The 30-30 and larger cartridges will benifit with a dacron filler with the medium/heavy 160 - 190 gr bullets with powders from 2400 - 4895 in burn rate if lading density is 80% or less. The dacron filler will keep the powder positioned against the prime for a smaller and more uniform ES.

Many now pursue a lower SD which is ok if it is in line with the ES. However, many times i have seen a low SD with a high ES. Comparing such a low SD with the highe ES tells us that one or more (depends on the number of shots in the test string) is out side the "norm" and will drop out of the group (if it is in the group) at longer ranges. I've found the best loads accuracy wise will have an SD that is about 25-40% of the ES. Those loads will usually give even shot distribution withing the group over extended ranges. They will not have a small cluster in one spot with 1 or 2 shots "out of the group" even if the group is small as in 1.5 moa or less.

Maniac; if your previous loads are with powders in the burning range I mentioned then I suggest a work up with what appears to be a good powder using a dacron filler. That will eliminated the ES problem and if the verticle stringing persists then you can bet it is rifle or shooting position related and look at those. Since you've BR experience it would probably be rifle related.

Larry Gibson

[geargnasher]

Ive often thought about filler,exspecially with my 4227 loads,but ive heard all kinds of srories about ringed barrells and stuff like that,so ive never tried fillers.I really have a suspition that it may be powder position giving me fits.Ive shot alot of h335 loads,and even max loads leave space in the case,although this powder hasnt bothered me in other rifles,maybe it is in this cantankerous thing!

Using filler is to a large degree a defined science, and if you know what causes ringed chambers you will know how to avoid any risk of such. The problem is that the larger spectrum of the shooting community only remembers "ringed chambers" when filler is mentioned, because somewhere, some time, someone actually did some testing to verify that certain loading conditions with fillers will ring a chamber every time. What is lost is the knowledge to have the great benefit of filler without the risks.

Larry Gibson has some pressure testing equipment at his house, and quite an arsenal of test guns to which he's mounted strain gauges. He's been testing and reporting the effects of Dacron and other fillers on this forum for some years. If you want the straight dope on fillers, do some searching using his name and the words "dacron" or "filler".

Gear

[edit] Here's a current thread with some decent info:
http://castboolits.gunloads.com/showthread.php?t=131552

Here's a sticky in the Favorite Cartridge section with more good info and pictures: http://castboolits.gunloads.com/showthread.php?t=109280

[swheeler]

Ive often thought about filler,exspecially with my 4227 loads,but ive heard all kinds of srories about ringed barrells and stuff like that,so ive never tried fillers.I really have a suspition that it may be powder position giving me fits.Ive shot alot of h335 loads,and even max loads leave space in the case,although this powder hasnt bothered me in other rifles,maybe it is in this cantankerous thing!

Now that sounds like a smart move to me.

[milprileb]

I was told vertical stringing is a indicator that the lube
is failing on cast bullets being shot.

Maybe the original poster should choose a different lube
first rather than chase all those other variables which may
or may not be the problem.

Change of lube is cheap and quick fix