Does this seem correct??

[Robden]

I know they are only cheap and not precision instruments. I put two identical 12g cartridge bore lasers into my o/u shotgun. Once in the barrels they didn't move. Turning each one by hand they looked to be concentric.

At 10 feet the two laser dots were just over 2cm apart. At 30 feet they were 7cm apart. So it looks like, the further the distance the larger the gap. Shouldn't the barrels converge at some point?

Thanks for any help/advice.

 

[Freddypip]

I suspect this is nothing to do with the barrels and almost certainly all to do with the cheap laser pointers. Did you turn the pointers to check they were concentric at 30 yards ?

With those cheap pointers (which are inside a cartridge body) you are not checking the barrels but the chambers and when it feels like they are tight in the chambers it is not always the the case. If they are out by 7cm at 30 feet over a three inch cartridge you are out by 0.6mm which could easily be the casing ityself or the laser not being straight in the casing, before any question of the chambers arises.

At ten feet I would be quite pleased with those results. They are better than my shooting.

Thinking about it, and this is a question I cannot answer - Are the chambers parallel anyway in the monoblock and any convergence is down to the barrels alone. If the chambers are parellel your results could be even better.

It might be worth measuring the mid rib thickness at two points alone the barrel (avoiding any swell for the chambers & forcing cones and chokes etc) and seeing what you get.

 

[Robden]

I suspect this is nothing to do with the barrels and almost certainly all to do with the cheap laser pointers. Did you turn the pointers to check they were concentric at 30 yards ?

With those cheap pointers (which are inside a cartridge body) you are not checking the barrels but the chambers and when it feels like they are tight in the chambers it is not always the the case. If they are out by 7cm at 30 feet over a three inch cartridge you are out by 0.6mm which could easily be the casing ityself or the laser not being straight in the casing, before any question of the chambers arises.

At ten feet I would be quite pleased with those results. They are better than my shooting.

Thinking about it, and this is a question I cannot answer - Are the chambers parallel anyway in the monoblock and any convergence is down to the barrels alone. If the chambers are parellel your results could be even better.

It might be worth measuring the mid rib thickness at two points alone the barrel (avoiding any swell for the chambers & forcing cones and chokes etc) and seeing what you get.

Right, thank you, I see what you mean about the chambers. So ideally, I would need the lasers to fit and be centered and concentric in the barrel's muzzle.

 

[Freddypip]

Yes but I think errors in the lasers fit would make any results worthless.

is it a new(ish) gun. If so it unlikley to be out by anything much - if at all.

 

[Luke_(NL)]

How about setting up a pattern plate at ten, twenty and thirty yards and seeing what two shots fired from each the barrels tell you in terms of actual shot distribution? If the barrel convergence is a source of worry, take it out of your mind once and for all. Lasers won't tell you where the shot actually goes. 

Niggles of doubt will only reinforce belief (or the excuse) that something is amiss, whereas you want blind faith in the gun. Also I am 99.9% confident that Chinese manufactured laser cartridges are not within several minutes of angle, even if they fit the chambers perfectly (which they don't). 

 

[Robden]

Agreed. Patterning tomorrow.  Also agree about getting something in the head.

 

[Gavin]

Only if I felt there was something wrong (missing birds I thought I should have hit, missing constantly high,low,left, and so on) would I go near a pattern plate.  They can cause more problems than they solve  doubt can creep in.  A straight away clay  can tell you all you need to know.  If shooting a straight away  shows up problems then the pattern plate can confirm.  

 

[westley]

Only if I felt there was something wrong (missing birds I thought I should have hit, missing constantly high,low,left, and so on) would I go near a pattern plate.  They can cause more problems than they solve  doubt can creep in.  A straight away clay  can tell you all you need to know.  If shooting a straight away  shows up problems then the pattern plate can confirm.  

I NEVER go near any pattern plates EVER.  I tend to stick with the same choke/ cartridge combination for EVERYTHING (except Trap, which I rarely shoot). I know that when I miss a target that I am 'behind' it, cos there is always someone nearby to tell me  !

 

[balltrap]

I was told by a friend of yours that you once shot at a pattern plate and MISSED it  ? 

I NEVER go near any pattern plates EVER.  I tend to stick with the same choke/ cartridge combination for EVERYTHING (except Trap, which I rarely shoot). I know that when I miss a target that I am 'behind' it, cos there is always someone nearby to tell me  !

 

[westley]

I was told by a friend of yours that you once shot at a pattern plate and MISSED it  ? 

That must have been at Westley Richards in 1979, because THAT was the last time I shot at a pattern plate. The thing was I was within the control of their Gunfitter, who just happened to KNOW what he was doing.     

 

[Freddypip]

Robden. The guys are right in saying that little, if anything, is learned from a pattern plate. It is however cheap to try and there is no harm in checking the pattern from both barrels for convergence. I would suggest about 20 yards with a full choke. The wad should have fallen away by then and the pattern will be tight making it easier to find the centre. If you can't immediately see a difference, there isn't one. i expect that to be the case. If you can, it could just as easily be a variation in your mount !!!

 

[Martinj]

I bought one of these too, all it did was cause me to lose confidence in my gun. I dropped it in the chamber and the laser dot was low . . hmmm! so I rotated the device but there was no appreciable difference. I thought it might be a loose fit in the chamber causing it to droop and aim low so I wrapped tape around it, taking care not to overlap it. Now a snug fit in the chamber the dot was still low, maybe three-four inches at 20 yards. I tried it in other guns and they were more or less spot on so my new-ish 692 was the only one pointing low - this was a bit of a blow!! I did make a post on this site and got no really helpful advice other than just ignore it which was probably the best advice. As Freddy says, we are testing nothing but the chambers anyhow, (I do believe that the pointers are quite concentric by the way.)

Although my confidence has taken a beating, I can't say that my scores were too bad, I had a couple of high 80's and a low 90 at sporting recently, also I did a few rounds of DTL at the weekend, a good indicator of where the gun shoots so common sense tells me that I don't have too much to worry about, therefore- I'm going to forget the Laser and put my efforts into putting the shot in the right place

 

[Luke_(NL)]

The pattern plate is suggested for one purpose only here, which is to assuage the OP’s fear that his barrels disperse as range increase, rather than converge. A pattern plate will tell him whether that’s the case, whereas lasers or a ‘simple clay’ will likely not. I don’t understand why shooting a few shells into cardboard always evokes the ‘why I woud never’ reaction, as it may help in fact help the shooter who tries it. For me, it has helped my understanding of where I shoot and what my gun does. In this specific case it will certainly help the OP figure out whether something is amiss (likely not, but best to be sure).

@Martinj Did the 692 actually shoot any lower than the guns that were ‘spot on’ with the laser? 

I would sooner say that laser pointers in shotguns have no use for anything but mounting practice. 

 

[Martinj]

@Martinj Did the 692 actually shoot any lower than the guns that were ‘spot on’ with the laser? 

That's hard to say Luke, I don't use them much these days and haven't tested them in recent years, with my previous gun, a Silver Pig, I used to aim a little bit low, i.e. at the feet so-to-speak, this is only really possible at going away clays. I did 3 rounds of DTL on Sunday and found it best to shoot as I always did, I tried blotting the clay out with the bead but got better results when I could see the clay on top of the bead

 

[Luke_(NL)]

That's hard to say Luke, I don't use them much these days and haven't tested them in recent years, with my previous gun, a Silver Pig, I used to aim a little bit low, i.e. at the feet so-to-speak, this is only really possible at going away clays. I did 3 rounds of DTL on Sunday and found it best to shoot as I always did, I tried blotting the clay out with the bead but got better results when I could see the clay on top of the bead

Good to hear. No worries then as it appears the gun shoots high rather than low