Best .177 pellet for plywood pentation?

These are really accurate. Unless you want to jump to 10.3grain



those will penetrate much better.
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I don't kill plywood very often but I do use a yellow pine backstop for one of my targets and it appears heavy domes penetrate the best. Most all my shooting is with PCPs, in which case heavier pellets tend to produce more energy for a given state of tune. Just be aware if you are using a springer, increasingly heavier pellets will not generally produce more energy so I expect penetration will somewhat level off above some weight.

Also, you may find Bob's report using melt-and-pour soap as a ballistic medium. At least in this situation, pointed pellets perform no better than domes and they are almost never as accurate.
https://www.gatewaytoairguns.org/GTA/index.php?topic=42959

If your namesake is indicative of what you are hunting, you don't need to worry about penetration. Go with whatever is sufficiently accurate at the distances you will be shooting. To the extent that you should favor a particular head type, a wadcutter is absolutely devastating on small game and pests like rats, chipmunks, and even gray squirrels. It's the antithesis of penetration.

Here's an example of a gray squirrel taken at 30 yards with a wadcutter using a downtuned .177 PCP. Muzzle velocity just 625fps decaying to about 470fps at the point of impact.

https://youtu.be/TMC04JPmWns

Instant lights out. Placement is the top priority.