Guns with adjustable combs

[jwpzx9r]

Ian bud I am tying myself in knots but for no reason other than trying to see the reasoning behind POI changing. I have now reached this scenario .

A target moves over the sky thirty metres in front of a shooter at five metres high he shoots and breaks the target. The gun is taken and the comb raised say half an inch. The gun is mounted exactly as before and head is brought down onto the comb. To my thinking the gun will sit in the shoulder at exactly the same angle as before because the comb is parallel to the barrels. The same target is presented ... how can the POI have changed ? To hit that target the gun must be pointed to the same bit of sky and the angle of the barrels has not changed with respect to the target. Is it that because the shooter now sees the target at a different height over the barrels and therefore angle in relation to the bead so he has to change his POA to maintain the same POI ? Or is it that it is not possible to mount the gun in the same way after such a change in the comb height? One way or another to hit the target the POI must be the same because nothing has changed in terms of target or gun angle.

edit

My brain has fried for long enough will someone please give valid reason why the POI would change when changing the height of the comb assuming the target is the same and hit both times... please

 

[ips]

John

weather we think we see or use the bead or barrel is probably immaterial as we have to at least be aware of were it is and were it is pointing therefore let us assume for your scenario that we are aiming with the bead. Your 1st shot with a 50,50 pattern you shoot when the bead touches the front edge of the clay. Gun comb is altered radically for this exercise the pattern is now 70,30 high you mount exactly the same and call for the target you shoot as the bead touches front edge of target. Now this is were it gets interesting. At close ish distance you will still hit the target but probably a bit chippy as your not centre of pattern now as 30% is below at a distance of lets say 55 yds at ot and a low straight one you could possibly miss over the top but you know gun shoots high now so you sub consciously shoot under the target you probably still miss but this time under it because you were frightened to push through the target. Interesting further point to chew on, at what poi ratio would the above even come into play whereas you missed totally and didn't even chip with the edge of the pattern ?

This i think is the point that hammy and i made earlier how much difference in reality does a mm on or off the comb actually make. I would hazard an educated guess that a poi ratio of 80-20 before it becomes an issue this is based on the DTx that i had which did shoot at about that ratio and for my sight picture/perception was a nightmare.

I seem to remember a figure of 2mm on comb effects pattern by 6" but i Cant remember the distance but centre of a 30" usable pattern altered by 6" is that really going to have any real effect ? I doubt it therefore why spend all that time fiddling with the thing.

Just my take on it of course.

 

[jwpzx9r]

Ian to be honest everybody has been very good in their efforts to educate me on the finer points of this aspect of shooting , I for my part am perhaps trying to think a little too much in two dimensions and am side tracking the issues. I am going to stop thinking about this now and shoot the damned gun! Thanks for the effort and input.... even though I find myself saying yeh but  

 

[Irishgunner]

Sight picture on say a hanging crow bottom edge of the clay flat shooting gun, rase the stock 10mm and to break the same target you would have to see daylight under the target to break it, with the higher stock your eye is higher over the rib so to see the same picture you must rase your barrel and in doing so you rase poi, mount your gun at a fixed object now come off your stock ( rase your head 10mm off the stock ) and you will see the gun looks to be aiming low on the fixed object rase your barrels till they are bang on the fixed object with your high head hold then lower your head back on the stock you will see the gun is pointing over said object,

 

[ips]

A pleasure as always John, as you know i enjoy a deep discussion or even a heated debate at times its all good fun.

I will end on these final thoughts which i have learned are correct for me over the last 28 yrs

1 - There are many different styles and techniques and many different ways to set a gun up there are a few accepted text book things to do but in reality there just average starting points.

2 - Everybody sees things differently and perceives the target in different ways sometimes it is not actually what you think it is but it is how you perceive it.

3 - Considerably more targets are missed as a result of human error rather than gun fit, particularly comb height as the tolerance of poi ratio is quite forgiving given the size of the pattern and the available adjustment of the comb.

4 - There is no right or wrong way IF whatever your way is, works.

5 - From my experience the most common cause of a miss is trying to hard closely followed by not seeing the target correctly, somewhere quite a long way down this list is poi as you can and do adapt to it (too a point of course)

 

[Mick Shaw]

Ips you have the patience of a saint, :rabbi:

 

[RobertBeard]

"If I take my gun and mount it as normal then bring my cheek down onto the stock as I do the barrels will point in x direction." 

John

I am very much a beginner at this but have been taught that mounting the gun should be one movement.  What you are describing is two movements.  The second being when you lower your head onto the stock which implies that either you are not mounting high enough in the first place or you need to raise the comb to get the fit right.

Please tell me to b***** off if this is an unhelpful interference on your thread.

 

[Hamster]

John,

Many years ago before I had twigged that lowish sporter stocks were not good news for me, I experimented by adding layers to a Beretta 682 in order to get a better view of the target and stop myself head lifting. 

This was in the days when we all assumed that slapping an adjustable comb on a gun enabled the user to alter the POI at will. What I can tell you is that it took some time before I realised that paying too much attention to what this layer business did or didn't do, the scores didn't magically go up at the rate I was hoping for. As mentioned previously there were times when trying to ride targets led to misses; I even recall shooting DTL and finding it hard work so would hold my head slightly higher on purpose thinking this would have the same affect as raising the comb (why wouldn't it ?) but of course this also had less than satisfactory results. I had that stock eventually raised by a 1/4 inch but I think it sprung back.

When I got my current 682E around 14 years ago I spend a bit of time experimenting with comb heights, mostly of course on actual targets but also on pattern plates. What I found was that from dead flat (very little visible rib) to a nice bit of rib, any POI variation on a pattern plate was all but imaginary and could be accounted for with shot to shot variation caused by shooter error. BUT it made a very definite difference on targets because seeing more easily around the target meant my focus stayed on finding the line, tempo etc, instead of worrying about loosing sight of targets. 

The other thing I found was that there was a definite point of diminishing returns, i.e, you can have too much height of eye over rib. Not only does this lead to a feeling of detachment from the process but can also start to affect the recoil cycle and comfort of the various contact points; the sensations can all begin to feel very strange with too high a comb. What I did not find was the pattern moving upwards significantly either on a plate or such that you had to start thinking of giving things hold under. It may be that other guns / shooters differ in their experiences.

 

[jwpzx9r]

"If I take my gun and mount it as normal then bring my cheek down onto the stock as I do the barrels will point in x direction." 

John

I am very much a beginner at this but have been taught that mounting the gun should be one movement.  What you are describing is two movements.  The second being when you lower your head onto the stock which implies that either you are not mounting high enough in the first place or you need to raise the comb to get the fit right.

Please tell me to b***** off if this is an unhelpful interference on your thread.

http://www.renatolamera.it/ita/renato_lamera.php?piattello=renato_lamera_video&filmati=2011_07_08_la_corretta_postura_in_pedana

Robert I would never do such a thing .... but you may not have heard of Renato Lamera and he very much disagrees with your tutors, watch the video and be educated! Oh how I wish to go and have coaching from this man! I am very, very seriously thinking about it!

http://www.renatolamera.it/ita/renato_lamera.php?piattello=renato_lamera_video&filmati=2011_07_08_la_corretta_postura_in_pedana

 

[ips]

Ooh gun mount debate, this could be interesting. Gun to face or mount then face on stock ?

over to you

 

[ips]

. What I did not find was the pattern moving upwards significantly either on a plate or such that you had to start thinking of giving things hold under.

exactly my point hammy, this is why I now prefer a flat gun for trap much easier to push through the target than to guess a hold under on a low target

 

[jwpzx9r]

Ooh gun mount debate, this could be interesting. Gun to face or mount then face on stock ?

over to you

Now this is not of my making Ian but I am not going to argue with Renato on this one, I use it I like it ... is it right ??? I don't know but it feels right and that is what matters to me!

 

[ips]

John

I am sure you sneak these potentially heated topics in deliberately

 

[jwpzx9r]

Ian as I sit in the sejour enjoying a glass of vin rouge in front of my roaring log burner I did not do that !  I was replying to Roberts post which contradicts what my current online coach, since I cannot find an onsite one, advocates as the best gun mount for Olympic trap. I cannot unfortunately speak nor understand Italian but I think he is indicating a better chance of more consistent and  proper connection between gun and shoulder by this method. I may have this wrong but I do use it it feels right for me!

 

[ips]

What exactly is the method you refer to, purely out of interest.

 

[Wonko the Sane]

Just a couple quickies

First, the adjustable combs on the guns I have are easy adjustable over an 1" vertical range.  Flat on the wood one is too low for me to see past the action and the other three are somewhere below 50/50 (that's just a guess since I never shot it).  The 1" adjusto will easily take that to a full pattern (100/0) high, which to my understanding is that the entire pattern is above point of aim so center +/-15" high the same way 50/50 is 0" high.  I set the combs so that the pattern center is about 5-6" high at 40yds.  Not sure how to quantify the drop measurement since only a couple of the barrels have kinda the same height rib and I never bothered to measure how high the back of the Perazzi action is relative to bore center which would give me standard ref.  A point being that the ribs ranging from flat to about 6mm high at the step have nothing to do with where the gun shoots as long as I can see over them.  Comb height relative to bore center is all that matters.

The second point is that flat rib does not mean flat shooting gun.  See above.

that's really all I can contribute so here's a couple others

it's been fun

Charlie

http://www.mn-trap.org/tech_corner/n_winston/Point_of_Impact_and_Pattern_Testing_at_13_Yards.pdf

and Krieghoff says this - wonder who fooled them about it making a difference???

Krieghoff is proud to offer the K-80 Trap Special Combo with fully adjustable high-post rib on the over & under, unsingle and top single barrel for point-of-impact (POI) adjustments. Built around the proven K-80 receiver, the Trap Special comes with 30" or 32” O/U-barrels and 34” Unsingle or Top Single barrel. The Trap Special can also be ordered as a complete gun with the barrel of the shooter's choice.

Titanium Choke tubes and a Monte Carlo trap stock with adjustable comb specifically designed for the high-post rib are standard features. Shipped from the factory with a 70%/30% POI in all barrels, the rib can be adjusted so the gun shoots a fairly flat 60%/40% or up to almost a full pattern high.

The higher rib provides for good visibility around the gun and quick target acquisition. An added benefit is the low recoil due to to a "heads-up" shooting position.

Particularly unique is the fully adjustable O/U-barrel for shooting doubles. Not only can the point-of-impact of both barrels be adjusted simultaneously, you may also adjust the spread between the 2 free-floating barrels by changing the front hanger which results in different POI for each barrel, if desired. This way the bottom barrel can be set to shoot higher than the top barrel.

The K-80 Trap Special Combo with the complete point-of-impact adjustment is a hallmark of Krieghoff shotguns.

 

[RobertBeard]

I'm just a humble sporting shooter and this Italian method is probably fine for Trap.

I seem to have upset the original thread good and proper now!

 

[jwpzx9r]

The one demonstrated in the vid

 

[ips]

John

I havent seen it as on me phone at the mo.

 

[jwpzx9r]

Ian essentially the gun is mounted down into the pocket with an upward angled gun the head is then brought down onto the stock and then the gun is levelled  into the  hold position. It looks quite mechanical but I find it works for me... I could be very wrong but it may also take pitch out of the equation to some degree.... I could be wrong though on that one. Anyway I don't argue with Renato what ever he is actually saying