Changing Perfect Convergence


Hi Bruce,

After finally getting my Perazzi mx8 U&O trap gun, { fixed chokes & fixed stock } I have been out to several shoots and find I am hitting the bottom of most of the clays even though I see a little bit of rib when I put it up, So checked it out at the pattern board and the bottom barrel is shooting flat 50/50,which is too flat, the top barrel is also shooting 50/50 which is correct.

This gun is brand new and I am not sure what to do next, if I put an adjustable comb on it and raise it the top barrel will be shooting to high. I have others check the pattern at 16, 30yards also seeing just a little rib, same result with the bottom barrel shooting 50/50. Any advise would be appreciated.

Brian

Dear Brian,

First of all, congratulations on buying a marvelous gun. A Perazzi MX8 is one of the best trap guns made. Just check the Olympic records. Then see how many times you see the name Browning or Krieghoff mentioned.

You say that the Under bbl is shooting 50/50 which is too flat for your needs, but that the Over bbl is just right at 50/50. Sounds as though you would prefer the Under bbl to shoot high and the Over bbl to shoot flat.

Personally, that would drive me crazy. I go to particular lengths to get both barrels shooting to the same point of impact. I never once thought that others would go to equal lengths to get them to shoot to different places! Just shows you what I know.

Most O/Us “want” to shoot the top barrel high and the bottom barrel flat. That’s because the axis of recoil from the top barrel is higher than that of the lower barrel, so the gun recoils upward more when the upper barrel is fired. Gun makers go to great lengths to correct for this and are very proud when they can achieve correct convergence such as you have now.

It doesn’t always happen though. I once had a Superposed and a Perazzi Comp I O/U, both of which shot the top barrels very high and the bottom barrels flat. I parted with the guns rather than do the tinkering necessary to correct this.

It’s not a big deal for a good choke man to alter a fixed choke so as to change point of impact. A skillful smith should be able to raise your Point Of Impact on the Under bbl by a good bit. You will lose some choke constriction in the process, but you should be able to get any reasonable POI you want.

But why aren’t you happy with both barrels in perfect convergence? That is the Holy Grail of O/Us after all. I see your web address is NZ, so perhaps our Kiwi cousins enjoy different trap games than we do in the States.

I set all my trap guns to shoot a flat 50/50, especially the ones I use for Olympic bunker where hard angle bug cutting ground skimmers are often seen (or not seen quite clearly). A high shooting gun would be over the top.

In ATA trap as shot in much of the USA, where the bird rises predictably to a fixed height, I’ve simply learned to cover the bird when I shoot with my flat shooting guns. Ditto doubles where the first bird is rising and the second has pretty much peaked. I use a fairly low hold on the first bird so that I get a little upward movement to the gun. That movement builds in the necessary lead. Other shooters like to ambush their first shot on double with a dead gun where they can watch the bird come up under the barrel. For this they like a first barrel that shoots high and perhaps that is your situation. There are a number of different techniques that work and I certainly don’t pretend to be an expert in all of them.

If it were my gun, I’d try shooting it the way it is for a little longer, trying to cover the birds more to get the needed elevation. If that didn’t work, then I’d add some temporary stock height with tape, but I’d still keep the POI of both barrels the same.

If you do absolutely insist on an O/U with barrels that shoot to different places, you can

1) get one fixed choke obliquely ground so as to shoot higher, or

2) get Briley to install screw chokes. Briley can make some eccentric chokes for the lower barrel so that you can tune your point of impact.

A lot of people would be overjoyed to have a Perazzi with perfect convergence that shot 50/50. Are you sure you want to change the gun rather than shoot it for a while and adjust your technique?

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC

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