100-1000 or more depending on specifics
The Perazzi DB81 was produced in 1981 for the well known trap shooter Dan Bonillas,hence the designation DB81. Ivor Dadswell.
there are tubes inside that trap air
At 16 yards, probably the improved modified choke in a 30 inch bbl is the most commonly used
They have been selling for $400 to 675 depending on condition and extras (choke tubes, stock quality, original box etc.) Blue book values them at $350 in 80% to 590 in 98% condition.
Would not recommend using a full choke or even a 20 gauge, 12s are much better
The standard choke for trap shooting is full choke. If using the largest, widest choke pattern, there is a good chance that that you can 'miss' your target if all of the bbs go around your target. The clay can slip through a gap in your pattern and it would be a miss, even if you were aimed right at it. That is why most non-beginner trap shooters use full choke. When using full choke, it is almost guaranteed that you will hit your target if aimed at it. However, I would not advise a beginning shooter to use full choke. I advise that you use your modified choke if you are a beginning trap shooter. You are still very likely to hit the target using modified, so 'missing' is not a problem. Also, it gives you a wide enough pattern to be likely to hit the target, and know where you are aiming (left, right, high, low) and how to correct your mistake. Once you are comfortable with modified, move up to improved modified or full choke if you want. In fact, I have been shooting for 2 years and I still use modifed from the 16 yard line. I don't have a problem with it. It works for me, and it should work for you.
The choke you use depends on your target rather than the type of shotgun. For example: if you are shooting skeet, you would use improved or modified cylinder, but if you are shooting trap, you would use full choke.
To trap inhaled particles and move them out of the airways.
Impossible to answer without an appraisal
To trap inhaled particles and move them out of the airways.
Need to know if it has the box, papers, accessories, gauge, barrel length, choke, condition, finish.
A Choke manifold benefits when placed downstream of the sand trap since it is not exposed to the abrasive sand. However, there are times when it is necessary to place a choke manifold upstream of the sand trap. The most common reason is that the pressure at the wellhead is higher than the sand separator rating and must be reduced. Another reason is that the new well is producing mostly liquid and the manifold is used to shunt the liquid directly to holding tanks. As the flow from the well dries out, the manifold makes it easy to change the flow from tanks to sand trap, and from there, into the Test Separator.