OzFclass

Hi all,

I have come to a point that I need assistance with a unusual issue with my 284 and I need some help.

The problem I have is that, whether the barrel is clean, dirty, or fowlers shot thru prior, I suffer from vertical issues, but only for the first 3 shots.

First shot always high on the target, (make adjustment), next shot, 180 degrees low, (make adjustment) next shot low but in between previous shot and "X" ring. 4th Shot on the money, and away we go, with no vertical issues, until the beginning of the next round, when the whole process repeats.

So my first and second sighters are high and low, and the first scoring shot is low and most of the time in the 5 ring.

The gun can shoot, most weekend I can give the Great Mr Barry Lewis, a run for his money, but in the end I am always losing the first shot in the string.
Barry is of the opinion that I have a setup issue, i.e. rear bag, front rest or me, but I am at a lost which way to go.

Any assistance, recommendations would be greatly appreciated.

Regards

Craig.
Brisbane Rifle Club.

Make sure that the rear sand bag is not settling on the first few shots.
After the first shot, where is the scope pointing? If it is high on the target than my money is a rear bag issue.
Does the rifle stay level after the first shot or does it end up tilted to the right? If so the front bag may not be tight enough.
just a few possibilities.

A friend was having this exact same problem up until a week ago. (first 3 shots pretty bad, then the rest really good). Once we reduce the bullet jam, it became super consistent. Might be something to try???

Hi Rod,

I am running 80 thou Jump on the Berger Hybrids. I settled on this after thinking the problem was load related. So I spent several days at the range starting from scratch.

One thing I did notice last night, after trawling the internet for several hours to research it, was that the rifles balance point is nearly 100mm forward of the recoil lug, so the rifle is very front heavy. I worked out I need to add 680 grams to the butt area to bring the CoG to back just on the recoil lug, or just aft.

This may not change a thing, but I thought it cannot hurt to try.

Rod you coming up the the Nationals this month?


Craig.

craig,
cog on the receiver ring is about ideal for a dangerous game rifle, but too far back for a benchgun.
your issue could be bag packing or barrel condition. have never seen a barrel condition do what you said, so more likely bag packing or consistency of technique.
be careful tightening your front rest as norm suggested.
it aids tracking, but rules state that the gun must be able to be lifted straight up out of the front bag.
there are people who unwittingly cheat by clamping forends, and get quite upset when this is pointed out.
sometimes getting someone else to shoot your rifle can help eliminate or establish technique problems.
keep safe,
bruce,

Is it a cut rifled or button rifled barrel? Some say that button rifled barrels tend to wander more during warm up.

Craig, thats an interesting problem you are experiencing and you have provided some good details for me to have a stab at what might be wrong.

If every first 3 shots perform the same each time you shoot the rifle regardless of clean or dirty barrel and you have 80 thou jump which rules out chambering inconsistencies then maybe consider these suggestions.

1. Are you shouldering the rifle with the same butt pressure each time you fire or do you slowly increase, (unknowingly just a little) with each shot until you settle in on the fourth shot?

2. To help prevent vertical the consensus is to have one firm/hard sandbag and one soft/compliant bag. Doesn't matter which end of the gun the bags are placed just so long as you are not resting the rifle off bags that are both hard.

3. A work around if you cant find the problem would be to adjust for the third shot with a sight change or hold off to centre it then use sights as normal for rest of string.

It would not hurt to try a much shorter jump of 15 to 30 thou for the hybrids, as generally they work well from 15 thou on out. Its a tricky problem but work thru it with just one change at a time until you find the cause. Good luck with it and please let us all know what you find.

Ian

Craig,

It may be a small receiver barrel joint problem. If you remove the barrel apply some bearing blue sparingly to the face of the action and re-insert the barrel, take apart again and check the mating surfaces. A nice even bearing on both barrel shoulder and action face indicates the setup is square. Unless the barrel threads feel loose with a square setup its unlikey the joint will move if there is sufficient tension on the joint.

On the other hand if the smear of bearing blue has a tapered look to it like a long tadpole or a thin line to it, this may indicate the thread is not cut square to the barrel shoulder or vice versa which may cause the joint to flex until the barrel warms and binds. So it doesn't matter if the barrel is clean or dirty.

Also, it is the first few threads on a barrel that do most of the work. If these are cut on a lathe that imparts a taper in the wrong direction this can exacerbate a flex problem. Any loose front threads will not help as rear threads naturally flex. Be assured that properly cut "V" threads self centre and the barrel can draw up smoothly, but not loosely. Yes, lubricating the barrel tang is a must. We tend to naturally crush the front threads on drawing up a barrel and so the rear ones have that bit of flex anyway.

Undersized major diameter of the tang is a real problem in that the barrel tends to ride on the peaks of the threads and is more subject to movement.

A minor problem in the fit can be rough threads.

Another problem is that the wrong thread depth is cut, in that the peaks of the "V" thread bind on the trough of the mating thread. Feels like a real tight fit, but you are looking for trouble. Only the faces of the threads are meant to touch in the traditional "V" thread. This is exacerbated if a bit of grit is picked up on fitup.

This flex problem may also show up in a rechambered barrel if old threads are chased up without proper consideration of fit. In this case using your hands, drawing the barrel and action together, feel for the loose fit before the threads are chased up.