M305 Vertical Strings *Updated on page 3*

MagnumPeanut

MagnumPeanut

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I am going to throw this gun away soon. I am so frustrated I could puke.

I am getting terrible groups, like 4-8" at 100. Horizontal is great, but the vertical is pathetic.

I read up on it and thought it may be the bedding. It was already bedded but wasn't 100% job. I ground it out and it is perfect now, it can't get any better.

I had a Springfield break on it so I tried it without that and it was the same.

It seems to shoot lower with every shot. I have even adjusted to go higher today as I started to go off paper. I have the Sadlak mount and could it be mounted wrong?

The first time I mounted it I couldn't hit paper at 25 yards. It was WAY low.
I took it off and followed the steps perfectly and it still low as I am pretty much out of elevation. Now it seems that it may not be holding zero.

Other thing is that every 5 shots or so a brass jams between the front of the mount and the action.

I know it is not the scope. I have used the scope on a different rifle and it is solid. I upgraded the optics on that rifle and moved that scope to this rifle.

Anyways I am getting pissy with this rifle.
 
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Don't know if it might help, but I have to regularly tighten my gas plug on the front of the rifle (every 10 shots or so). First jammed brass I had with mine, I noticed the plug had unscrewed/backed out. retightened, no problem after. I now check it every few shots.
The change in pressure (gas plug letting more propellant escape without enough backpressure) might explain the wandering shots... Mine's a 2009 M305, switched to a Boyd's stock.

HTH
 
Could ammo be the problem,? Inconsistent powder charges could result in the vertical strings. It does not sound like the rifle as I would think the groups would be all over the place, not just vertical?

To make sure its not the scope or mount, try taking off the mount and using a rest shoot with irons?
 
i feel your pain, today mine shot it's best ever 5 shot group 3.5 inches. During load development I was getting about the same as you 4-7, sometimes worse. Mine doesn't string though, it's all over the place
 
LeeEnfieldNo.4_mk1 said:
Could ammo be the problem,? Inconsistent powder charges could result in the vertical strings. It does not sound like the rifle as I would think the groups would be all over the place, not just vertical?

To make sure its not the scope or mount, try taking off the mount and using a rest shoot with irons?
Click to expand...

I am using new Win brass and H4895. 150 g Hornady FMJ as well. I doubt its a velocity problem as my powder measure works great.

rhino62 said:
What is the grouping with iron sights?
Click to expand...

I need to try irons next. I would have today but I didn't have the tools at the range to take the mount off.

I really think it is the mount. Anyone else have problems installing the Sadlak?
 
TAC PRO said:
Try shutting off the gas and cycling the action manually to rule out oprod or piston issues.
Click to expand...

Turn the spindle valve from up-and-down slot to horizontal. That will eliminate all the extra variables from the op rod and spring cycling back and forwards.

If you are a skilled shooter, then diagnose the rifle. If you are not a skilled shooter, diagnose yourself. Do you wear ordinary eyeglasses, or are they high index? Depending on where you look through the lens, the sight alignment will not be the same. (I found this out from many relays with vertical stringing with my target rifles.) For me the solution was a very finely adjustable cheekrest.

Your box standard Norinco stock will not align your head properly to any scope. Unless you have perfect muscle memory, your head isn't going back to exactly the same spot. So whatever you do, build up the cheekrest and give yourself a 'kisser' to index with your lip.
 
maple_leaf_eh said:
Turn the spindle valve from up-and-down slot to horizontal. That will eliminate all the extra variables from the op rod and spring cycling back and forwards.

If you are a skilled shooter, then diagnose the rifle. If you are not a skilled shooter, diagnose yourself. Do you wear ordinary eyeglasses, or are they high index? Depending on where you look through the lens, the sight alignment will not be the same. (I found this out from many relays with vertical stringing with my target rifles.) For me the solution was a very finely adjustable cheekrest.

Your box standard Norinco stock will not align your head properly to any scope. Unless you have perfect muscle memory, your head isn't going back to exactly the same spot. So whatever you do, build up the cheekrest and give yourself a 'kisser' to index with your lip.
Click to expand...
What spindle valve?
 
if you look at the front of the rifle , at the metal bit, you'll see 2 vertical columns= the first is your gas plug and collar, the second contains the spindle valve- it looks like a slotted screw head- push in and turn- that'll turn the gas off- geez- don't you guys LOOK at the manual or did you not get one- fm23-8
one other "trick" i can think of is to flip the plate over the buttplate to the horizontal position, same as you would position a m14e1 - that'll "lock " it into your shoulder and help with your head position
 
gas.JPG


The slotted round part protruding from the right side of the gas assembly is pushed in and turned to shut off the gas flow to the piston. The slot should be in the horizontal position to shut off the gas flow. This prevents the action from cycling in the semi-auto mode.
 
t-star said:
if you look at the front of the rifle , at the metal bit, you'll see 2 vertical columns= the first is your gas plug and collar, the second contains the spindle valve- it looks like a slotted screw head- push in and turn- that'll turn the gas off- geez- don't you guys LOOK at the manual or did you not get one- fm23-8
Click to expand...
Thank you, I have never tried to shut off the gas supply on my M1A, but I now realize that it was necessary with the M14 in order to be able to launch grenades!
 
inspect your flash hider, make sure it hasn't loosened slightly....
check gas lock tightness. if gas lock is too tight it can cause vertical stringing as the barrel heats up.

one beautiful thing that the chinese accidentally did was how they machined the gas lock. it goes on tighter or looser depending which side you choose to thread on.

example , for a fun gun, blasting away, no real concern for barrel heating or MOA accuracy, you are aiming center mass A zone. the gas lock should be looser, coming hand tight at 7:00 and then backed off to 6:00 . general battlefield rifles should be set up in this manner. less tension at the gas lock, means reduced stringing efect as the barrelled assembly heats up.

for target, cold barrel shooting, gas lock should come hand tight to 5:00 and tool tight at 6:00, tighter than this and as the barrel heats up YOU WILL GET STRINGING in most standard profile barrels.

Gas pistons have a HUGE affect on accuracy as well. When all other accurizing work is done on my rifles, I then do a piston test with as many pistons as i have that will fit the cylinder. i let the rifle and load of choice dictate which piston it performs best with. this is one step to final accurizing that I've learned from my friends in the US...... a long time practice by some of the best National Guard shooting teams in the states.
 
M14 stringing

M14Doctor said:
inspect your flash hider, make sure it hasn't loosened slightly....
check gas lock tightness. if gas lock is too tight it can cause vertical stringing as the barrel heats up.

one beautiful thing that the chinese accidentally did was how they machined the gas lock. it goes on tighter or looser depending which side you choose to thread on.

example , for a fun gun, blasting away, no real concern for barrel heating or MOA accuracy, you are aiming center mass A zone. the gas lock should be looser, coming hand tight at 7:00 and then backed off to 6:00 . general battlefield rifles should be set up in this manner. less tension at the gas lock, means reduced stringing efect as the barrelled assembly heats up.

for target, cold barrel shooting, gas lock should come hand tight to 5:00 and tool tight at 6:00, tighter than this and as the barrel heats up YOU WILL GET STRINGING in most standard profile barrels.

Gas pistons have a HUGE affect on accuracy as well. When all other accurizing work is done on my rifles, I then do a piston test with as many pistons as i have that will fit the cylinder. i let the rifle and load of choice dictate which piston it performs best with. this is one step to final accurizing that I've learned from my friends in the US...... a long time practice by some of the best National Guard shooting teams in the states.
Click to expand...

My experiments showed stringing in varying degrees in all gas lock tensions -

My best results were with 5:00 hand and 6:00 tool tight, cold 1 M.O.A group, but with non stop shooting getting the barrel real hot -
I end up with a 1 inch wide 3 inch long (extending downwards) pattern.

Let the barrel cool, and the 1 " group goes right back to the top again.

In slightly looser gas lock tensions the bottom groups were wider.

Much looser and the groups were just large - no pattern determinable due to bullets printing every which way.

The only system that prevented the stringing is the stock with the ball bearing pressure points on the barrel and gas cylinder.

Thomas - have you done any tests with the SAGE stock top barrel tensioning screw ? It seems to mimic ferrule lip tension. More tension good ? Less tension ?

Also - ferrule lip pressure must have some affect as well . More tension? Less tension?
One un bedded gun with NO lip pressure shoots very well, and others I have match bedded with high tension shoot very well -:confused:

swingerlh.gif
 
yes chopper, the sage set screw has some affect on stringing
bedding could also be an issue.
when i NM bed rifles to walnut or gi stocks i have 3 fixtures in use.
one is a gas band that has the ferrule lip cut off
second is an adustable spacer block that elevates the gas assembly/barrel in the stock
and the third is a clamping fixture that attaches thru the mag well, clamping action to stock

using these fixtures allows for the action to be bedded correctly to achieve approx 40lbs of pressure at the gas band ferule lip.
the stock should ONLY contact the gas band on the ferrule lip and there should be a desired 15thousands" gap between the face of the stock ferrule and gas band

i have never owned a M14 that had a vertical stringing issue, but have corrected a few with piston swaps and correct stock bedding.
 
Magnum Peanut - thanks for posting re this issue because as they say 'I feel your pain'; I'm having the same issue and was convinced it was my mount ( SA 3rd Gen ) after swapping scopes etc to confirm it wasn't the glass. I'm now going to investigate the gass plug issue - think of it as I do: another genuine reason that you simply have to go to the range :)
 
Tomochan said:
Magnum Peanut - thanks for posting re this issue because as they say 'I feel your pain'; I'm having the same issue and was convinced it was my mount ( SA 3rd Gen ) after swapping scopes etc to confirm it wasn't the glass. I'm now going to investigate the gass plug issue - think of it as I do: another genuine reason that you simply have to go to the range :)
Click to expand...

These mount are famous for lossing the zero point. If you have these mounts please ensure that before during and after shooting that there big knobs are down tight. As I also had this issue until I switch over to an A.R.M.S. #18 mount and it seems to have disapeared.
Also get to a Hungry or Wet Coast clinic and get some one to check it over for ya. I even think M14Doctor offer's a rifle inspection service for ya.
 
Chopper1 and M14 doctor have pretty much explained exactly what I am seeing. Right now I am hand tight at 5 and habe to tap it with something to get it even at 6. If I let it alone for a bit everything seems to fix itself so I guess I need to test it with out the gas as well.
 
stringing

M14Doctor said:
yes chopper, the sage set screw has some affect on stringing
bedding could also be an issue.
when i NM bed rifles to walnut or gi stocks i have 3 fixtures in use.
one is a gas band that has the ferrule lip cut off
second is an adustable spacer block that elevates the gas assembly/barrel in the stock
and the third is a clamping fixture that attaches thru the mag well, clamping action to stock

using these fixtures allows for the action to be bedded correctly to achieve approx 40lbs of pressure at the gas band ferule lip.
the stock should ONLY contact the gas band on the ferrule lip and there should be a desired 15thousands" gap between the face of the stock ferrule and gas band

i have never owned a M14 that had a vertical stringing issue, but have corrected a few with piston swaps and correct stock bedding.
Click to expand...

SO - stringing is more affected by bedding and piston fit ?
It would have to be piston as I have seen correctly bedded SAGE guns string downward when they got hot. (Or perhaps to much screw pressure maybe?)

Trouble is - all my pistons mike the same - it would be nice to get oversize pistons to accomodate different diameter gas cylinders -

The SAGE screw doesnt affect sideways barrel whip, just up and down and tension changes when the barrel gets hot, expands in diameter and stretches.
Just touching seems to be the most accurate but may cause downward stringing. Excessive screw pressure opens up the group size.

I guess I have to experiment more with the tension. Gonna shoot more with no screw touching - total free float from the fixed op rod guide

I use 2 fixtures for glass bedding - the brownells kit -
The trigger guard u clamp and the aluminum barrel collar that fits in the stock ferrule- It gives appropriate ferrule lip pressure for NM configuration.
Are your bedding tools custom made ? The adjustability during bedding seems like a very good idea to accomodate stock and rifle variations.
swingerlh.gif
 
i don't know that pistons will affect stringing one way or another but i do know that regardless of mic'ing them and thier diameters, if you have enough pistons to sample in your rifle, you should eventually find a "sweet' one.
google Gus Fisher , his articles on accuracy improvements thru piston testing are very thorough and easy to understand. he has a dedicated sub forum on the us m14 forum TFL

barrel whip in any given chinese rifle with a standard profile barrel seems random amongst the thousands brought into the country, and "could" be a QC issue with how the barrel was made. Having more or less barrel whip as it heats due to the quality of the steel and process to make the barrel.
I have to admit, stringing is not a common thing i run across, when i have it was solved to the best of my knowledge by A, ensuring the gas band and stock ferrule are appropriately gapped to prevent the stock ferule from exerting forward pressure. without that necessary gap, the rifle strings upwards as the barrel heats up.
reversely with inadequate ferrule lip pressure, the rifle can string downward.

the bedding fixtures and many of the different tools and guages i have were made by a friend who has been a manual mill/lathe/cnc tool and die maker since before the days of widespread cnc use. the fixtures guages and tooling were made from U.S. military ordnance drawings. Some of these fixtures and guages can be purchased from brownells, others can be found in the kuhnhaussen manual and others by getting your mitts on the drawings used to make the few armoures sets made for these rifles.... I think only 3 or 5 were made. without the tooling, guages and fixtures i've invested huge coin into having made, i could not seriously offer the services and build quality i presently offer for these rifles.
 
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