A board member here was gracious enough to send me a box of WW 3/4 oz. loads @ 1100 fps to try in the .410 with the cross firing issues. I had the opportunity late this afternoon, and here are the results.
Before with 11/16 oz. loads at 1150 fps ......... rt. barrel
Same barrel with 3/4 oz. loads at 1100 fps
Left barrel with the 11/16 oz. load
Left barrel with 3/4 oz. load
Notice please how much of a difference the heavier payload at lower velocity made. The right barrel is now well regulated, where before with the lighter load it was cross firing badly. The left barrel is much improved, though not as perfectly centered as the right, it is nonetheless capable of much better shooting than before. It is only off by about 3" now, slightly low and right. I feel certain that left barrel's pattern can be moved by muzzle relief work to center it now. These were 20 yard patterns. Also, notice how much tighter the WW loads are than the RIOs. Those WW loads are deadly. I'll be ordering some of them shortly.
This is just an example fo what can be learned by shooting a plate. I'll never go back to guess work again.
Eureka!!
SRH
