Strange accuracy problem

[abolter]

I have a 5/35 Smc, it shoots 20 cal bullets. It groups 1/2" which I am happy with. However I noticed recently I was getting poor groups and worse still some misses at fox.

 

I have cleaned, tightened and adjusted everything and I also had the bore examined as it has had a 1000 rounds through it. The rifling is fine.

 

Having had a particulalry bad night on weds which resulted in 2 educated foxes I set up a target last night. I rested the rifle on a window bag on the bonnet and shot a 3" group!! I went back to 200m and it was a 6" group. Both groups were too high so I clicked the scope down and reset at 100m. This time I shot off the bipod, off the bonnet, and promptly got a 1/2" group!!!

 

It is a longbow scope and I know the parallax is a bigger deal with them. I wonder if this is all about parallax and crappy head position shooting out of a vehicle instead of off a bonnet or sticks?!?!

 

The barrel is free floating, I have checked.

 

I am going to try again this afternoon and deliberately get my head out of line to see the effect but has any one got any ideas I am a bit baffled

[jcampbellsmith]

Ask a friend to try the rifle. Regards JCS

[Offroad Gary]

Bonnet is never good for consistency - get your belly on the ground and load that bipod properly

[Danpd]

Put a decent scope on the rifle and check for accuracy etc. Then you can work out if the problem is rifle based or NV based

[gbal]

Put a decent scope on the rifle and check for accuracy etc. Then you can work out if the problem is rifle based or NV based

+1 : check with a scope-unlikely you are out 3 inches due to body position etc but only sometimes,though you can try deliberate parallax,as you say.

If someone else is there,have them try with the decent scope too....

Was it shooting 1/2 inch before with the same set up (NV,window,you).The misses may well be because you needed clicking down,and the bag to bipod somewhat complicates the test data (but probably not 3" worth).

 

Gbal

[abolter]

my confusion lies in the rifle shooting well from bipod and v differently off a bag?!?!?

[Gandy]

my confusion lies in the rifle shooting well from bipod and v differently off a bag?!?!?

 

Sounds daft but was the window in the full down position or partly raised, a friend has similar issues and we estimated that the glass pane was moving slightly under recoil although I imagine your calibre has negligible recoil???

[gbal]

my confusion lies in the rifle shooting well from bipod and v differently off a bag?!?!?

Agreed,that is the biggest puzzler here-though the scope was adjusted for elevation between the two groups,it isn't likely that reduced group size. We may only be talking about one 3 shot group in each condition (bag,bipod) but again,very unlikely that is the cause of 3'' to 1/2".unless it is one pulled shot in three?....... hence my question as to how it shot when ok-off bag on window,and/or bag on bonnet,and/or bipod on bonnet.....( and was POI about the same for the 3" and 1/2 " groups,after adjusting elevation.Be very helpful to have had some shots on target under the same conditions as missed foxes,too....There are just too many variables co varying to be very definative so far.... (three on firing position alone) 100/200 'too high' - presumably the 200 was less high.....or not?

Sorry to ask all this,but if you don't have clear well controlled data,then it all gets well.....a big group of maybes!

At least the rifle is shooting again,off bonnet/bipod,to point of aim/or where you want it? Wobbly window might be an issue-another uncontrolled variable-though you imply hits (off widow/bag?)have been OK up til recently,so unlikely window has changed....but NV has...(shooting quite high?).....

Fire at least two test groups from your window/bag position...if that is how you usually take fox shots(or at least the missed ones).

Gbal

[abolter]

further data, perhaps not in order Gbal.

 

I dont often shoot from the window, it was my mates ground and truck. I prefer the bonnet but the wild groups were off the bonnet.

 

The 100m and 200m groups were both the same for hieght, about 2" but that is possible based on trajectory. The 1/2" group was right in the middle of the previous 2. The 2 "bad" 3 shot groups were erratic, not 2 good and 1 pulled or wild, I would have simply blamed me then.

 

I would agree that the NV has changed POA tho

[gbal]

further data, perhaps not in order Gbal.

 

I dont often shoot from the window, it was my mates ground and truck. I prefer the bonnet but the wild groups were off the bonnet.

 

The 100m and 200m groups were both the same for hieght, about 2" but that is possible based on trajectory. The 1/2" group was right in the middle of the previous 2. The 2 "bad" 3 shot groups were erratic, not 2 good and 1 pulled or wild, I would have simply blamed me then.

 

I would agree that the NV has changed POA tho

2" high at both 100 and 200 is possible,I suppose...

Maybe it was the new factor-a different truck/window /possible cab position....but the puzzle really is the difference in bipod/bag off the same bonnet.(please don't say the engine was off/on -vibrations- between the two groups!)

Otherwise ,we have the basis for a two ronnies sketch....

Maybe it's ok-that was all I meant by now checking zero from your usual shooting position.(ie,as it turns out,your bonnet).

It will probably be fine,and the history can remain a mystery.

Gbal