Mr Auto

For waterfowling I like the advantages of the big chamber. 1. A 3" chamber can withstand more pressure than the smaller ones. This provides and extra margin of safety even when using the shorter shells. 2. You have more waterfowl load versatility. If you have a 3" gun and run out of shells but, all of your buddies in the blind only have 3 1/2" shells, you're done for the day. 3. 3 1/2" models can shoot traditional loads weight at higher speeds. 1 3/8oz of BB's (85) at 1,550fps in 3 1/2" VS 1 1/8oz of BB's (70) at 1,550fps in 3" for a loss of 12% in pellet count. Or the same 3 1/2" load vs a 3" 1 1/4oz load of BB's (77) at 1,400fps. You can also move up to a factory steel load with a velocity 1,625fps of 1 1/4oz. It only comes in a 3 1/2" shell.

Barrel length is all about the "feel" of the gun. A longer barrel does not provide tighter paterns over a shorter one. Velocity loss is between 5 fps to 10 fps per barrel inch up to a 30 barrel. Any model that has a rotary bolt face will have a longer overall length than a top locking lug design. A barrel length of 26" or 28" would be versatile. Hold the gun you want with both lengths to see which one you like the best.

Have you tried to adjust the fit of the gun with the shims?

Actually, the rotary bolt face is independent of the Inertia design. The older Benelli SL series and Beretta ES100/Pintail are both Inertia operated and do not have a rotary bolt faces. They are close to the more traditonal top locking lugs found on non rotary bolt's. The only difference is they used a bottom locking lug. There are several other gas auto's besides the M4 that use a rotary bolt face. The Beretta Xtrema's, and Franchi's 612,712, and 912. The Winchester 1300 pump shotgun used a rotary bolt face long before Benelli put one on any semi auto. A rotary bolt faces function is no different than a top locking lug. It's just a different way of locking the bolt to the chamber when the round is fired. The Rotary bolt has both advantages and disadvantages. Advantages: Reduced weight because a barrel extention is not needed when the face locks closer to the chamber. There is a little more lug surface making it a little stronger. Disadvantages: It takes more foward force to lock the bolt closed. They are easier to come out of battery accidently(unlocked). They add length to the bolt and receiver.,making the gun longer in overall length.

The M4 has been out since 2000 and was first tested by the miltary in 1998. It is gas operated only. The ARGO system stands for "Auto Regulating Gas Operated".

[ 01-18-2006, 09:42 PM: Message edited by: Mr Auto ]