220 vs 240 Sierra Match Kings

[Expatriot]

Trying to incease energy by using a heavier bullet in a subsonic is a waste of time. Subsonics penetrate to such a huge degree that even lightweight bullets will overpenetrate any soft target. Adding weight just increases the amount of energy that flies out the back side of the target.

I terminal tested 150gr subsonics and found that they blew through more than 16" of wet phonebook, through the bottom of the bucket and disappeared into the dirt deep enough that I could never recover one.

If a 150gr bullet can do that, what improvement would a 220gr offer over a 200 gr bullet?

[alorton]

Whether it is a waste of time depends on the application. While it is true that a bullet giving full through and through penetration won't be very energy dependent a 240SMK will still leave a larger wound track than a 150gr bullet provided that it tumbles. I'm not a fan of tumbling as a wounding mechanism, but the 240 will do more damage than a shorter bullet in that regard.

More energy would also be useful if you are shooting steel targets. The added downrange energy is helpful for knocking down the targets. Of course the larger bullet also has a better BC and won't lose velocity or energy as quickly, though that is a small issue with the range the 300 Whisper is useful for.

The biggest advantage, in my opinion, is reliability. It is easier to get an AR to cycle with a heavier bullet because it allows the use of more powder, which means more gas to cycle the action.

[TCCrewchief76]

Ummm...all things equal except bullet weight means the heavier projectile uses less powder...

[alorton]

Originally Posted by TCCrewchief76

Ummm...all things equal except bullet weight means the heavier projectile uses less powder...

If you are loading for a specific speed, like you do for subsonics, loading the lighter bullet will require a lighter powder charge. For example, I use 8.5 grains of 2400 for a 240 SMK but use 8.0 grains of 2400 for a 208 A-Max to accomplish the same velocity, 1050 fps. This is in a 10.5" Noveske barrel.

[N310toN170]

I've found that the heavier rounds cycle more consistently (inertia), and a greater bearing surface (accuracy) and occupy more case capacity (safety).

That being said... the price point of the 220 as compared to the 240 makes it hard to justify the 20gn's unless there's a very specific reason.

I prefer the 220's myself.

[TCCrewchief76]

Originally Posted by alorton

If you are loading for a specific speed, like you do for subsonics, loading the lighter bullet will require a lighter powder charge. For example, I use 8.5 grains of 2400 for a 240 SMK but use 8.0 grains of 2400 for a 208 A-Max to accomplish the same velocity, 1050 fps. This is in a 10.5" Noveske barrel.

It appears you are correct sir. My apologies...

[alorton]

Originally Posted by TCCrewchief76

It appears you are correct sir. My apologies...

No apology necessary. If you are loading conventionally your statement would be correct as the larger bullet eats up case capacity. If you were loading the 240SMK to max load and the 208 A-Max to max load the A-Max would use more powder. The difference is that the two wouldn't be going the same velocity. The speed limit on subs is what makes it different.

[Rikky Lee]

As I have noted previously, I have not ever had anything get up after being hit by a 240 and tell me it didn't do the job in a terminal fashion.