Sig Sauer MCX Rattler Cal-X Kit, 5.56 NATO 5.5" Barrel

Having a 300 blackout Sig Rattler I wanted the 556/223 barrel just so I could switch between the two as 556/223 ammo is much cheaper and easier to find. So I bought the barrel, along with the 556 handguard as the Sig website says that the 300 blackout handguard would not work with the 556/223 barrel. Doing research, I found that the 300 barrel and 556 barrel are not the exact same other than one being 300 caliber and the other 22 cal, the 556 barrel has the gas block way more forward on the barrel than the 300 barrel thus the reason the 300 blackout handguard would not fit with the 556 barrel. The switching of the barrels is super easy. Take off the handguard and then loosen the two hex bolts that clamp the barrel in. Pull the 300 barrel out and slide the 556 barrel in until it seats. (make sure the bolt is locked to the rear for easy swapping of the barrels) Then tighten the hex bolts, #1 first then #2 down and throw on the handguard and you are ready to rock and roll. So as the tile says "I don't care what people say about short 556 barrels", being a firearms instructor, I know that short barrels on the 556/223 bullet is not the best for that caliber bullet as it slows the velocity, accuracy and power of the bullet the shorter the barrel is. Understood, but Sig was able to work some serious magic and get this 5.5" barrel to not only shoot 556/223 ammo accurately (without keyholing) but with some pretty darn good power from such a small package. If you don't believe me watch a Youtube video and see for yourself what the 556 Sig Rattler is capable of. Now the barrel is way more expensive than it should be, but so is the Rattler although it's a great rifle. Adding the 556 barrel and being able to switch from 300 blackout (expensive and not as easy to find rounds) to 556/223 (cheap and easy to find rounds) is awesome. Also another great thing is once you have the 556 barrel installed you can buy a 22lr conversion kit that allows you to shoot 22lr out of the Rattler for even cheaper plinking and fun! This barrel even at the cost is well worth it! Now on a side note Sig says that if you buy the 556 barrel you have to buy the 556 handguard because the 300 handguard wont work with the 556 barrel....This is not true I bought the 556 handguard and it look as works great. But being the curious person I am, I put the 556 barrel on and then used the 300 blackout handguard and it fits with no issue other than a cosmetic appearance, which is that the gas block sticks past the front of the handguard by about half an inch whereas when the 556 handguard is on, only the flash hider sticks past the front of the handguard. So clearly the 556 handguard with the 556 barrel makes the gun look better when used together, but the 556 handguard is absolutely not necessary if you purchase the 556 barrel as Sig says it won't work, but I can attest that is not the case. Now with all that being said if you can pay $2500.00 for a 300 Blackout Sig Rattler and then another $700.00 for the 556 barrel then would another $200.00 for the 556 handguard really break the bank? The only real reason I will stay using the 300 blackout handguard over the 556 one is that once you put a front sight on it, you would also have to put a front sight on the 556 handguard as well. So for me the 300 handguard works just fine with about a half inch of gas block showing...not a big deal for me. Also when you buy the 556 barrel you get an extra bolt with it. You DO NOT need to switch this out with the 300 blackout bolt as they are the exact same (according to Sig), so not sure why they added it with the barrel although having an extra bolt is nice! So in closing the 556 barrel is well worth it, but the 556 handguard is not necessary even though Sig says it is.