Beware of scammers.

With the button, it is for the Model 74/740/742/7400 series semi-auto rifles. The rear of the follower will be squared off and this allows the bolt to hold open on the last round. The button allows the bolt to close when the mag is empty.
The 76, etc, etc series numbers are pump action guns.

Re-read the first post in this thread....
Especially the part about which bullet to use. This sentence in particular: "I will try to make this short in that you should NEVER use anything but round nose ammunition with these cartridges (all calibers), OACL is critical, and don't think for a minute ...

Here's my $.02 worth.
The one-piece base makes access to the ejection port more difficult. Some may argue that it is stronger. I would argue that if the action isn't strong enough to support the scope, maybe you shouldn't be shooting it. The two-piece is my preference for the model 700.
Hope this ...