Dave McCracken
Moderator In Memoriam
The 30" vent rib trap barrel that came on the 870TB here is a good one, and contemporary to the TB(1978) if not its original barrel. It is slightly off spec, being .733" instead of the standard .729", but I can live with a slight overbore.
For modern ammo, it was overchoked. Even with my fast loads of 8.5s, the pattern ran too darn tight, with a core of about 18" and quite a few flyers. The choke ran .695", or 38 POC. At 16 yard singles trap, a center hit meant smoke. Smoke is excess density and other than the confidence factor, has no benefit. I prefer the target just vanishing while microscopic fragments dribble down over 1/4 acre, and I often see it when I'm doing my part correctly.
So,Bill Gillette,the traveling gunsmith, came through the area recently. I left the barrel with him with instructions to lengthen the forcing cone and open the choke to 25 POC, or .0013" more open than of old.This runs around Improved Modified if one really has to name every degree of contriction.
For those coming in late, a longer cone, say 1 5/8", deforms fewer pellets so they stay in the pattern. It mimics a tighter choke thus. It also shortens the pressure spike, which spreads the recoil out over a slightly longer time, but I doubt I can notice the difference in a 9 lb trap gun shooting 7/8 oz and 1 oz loads.
Anyway, a dozen rounds of Trap, Wobble and Skobble went well, and a session at the patterning board showed I had picked up a few inches of core spread and a few less flyers. That's with my summer load of 8.5s, haven't patterned my winter loads of 7.5s yet. I expect results to be similar.
The mods cost about $130. Was it worth it?
Probably, since what I wanted was a more usable barrel. I wanted it set up for targets from 35 to 40 yards with a near perfect pattern spread, very good for 5 yards either way, and adaptable to dove shooting and open country upland hunting as well as the longer clay games.
With the long cone, overbore and realistic choke constriction, it's now a soft shooting, small shot precision instrument.
I'll let you know if my scores improve.
Questions, comments, donations?
For modern ammo, it was overchoked. Even with my fast loads of 8.5s, the pattern ran too darn tight, with a core of about 18" and quite a few flyers. The choke ran .695", or 38 POC. At 16 yard singles trap, a center hit meant smoke. Smoke is excess density and other than the confidence factor, has no benefit. I prefer the target just vanishing while microscopic fragments dribble down over 1/4 acre, and I often see it when I'm doing my part correctly.
So,Bill Gillette,the traveling gunsmith, came through the area recently. I left the barrel with him with instructions to lengthen the forcing cone and open the choke to 25 POC, or .0013" more open than of old.This runs around Improved Modified if one really has to name every degree of contriction.
For those coming in late, a longer cone, say 1 5/8", deforms fewer pellets so they stay in the pattern. It mimics a tighter choke thus. It also shortens the pressure spike, which spreads the recoil out over a slightly longer time, but I doubt I can notice the difference in a 9 lb trap gun shooting 7/8 oz and 1 oz loads.
Anyway, a dozen rounds of Trap, Wobble and Skobble went well, and a session at the patterning board showed I had picked up a few inches of core spread and a few less flyers. That's with my summer load of 8.5s, haven't patterned my winter loads of 7.5s yet. I expect results to be similar.
The mods cost about $130. Was it worth it?
Probably, since what I wanted was a more usable barrel. I wanted it set up for targets from 35 to 40 yards with a near perfect pattern spread, very good for 5 yards either way, and adaptable to dove shooting and open country upland hunting as well as the longer clay games.
With the long cone, overbore and realistic choke constriction, it's now a soft shooting, small shot precision instrument.
I'll let you know if my scores improve.
Questions, comments, donations?