BudsGunShop.com - Is he Walther ARms HK G36 considered an SBR?

Gregory no, it is not considered a SBR. Short-barreled rifle (SBR) is a shoulder-fired, rifled firearm, made from a rifle, with a barrel length of less than 16 in (41 cm) *****This is 18.1"***** or overall length of less than 26 in (66 cm)*****This is 37.8"*****, or a handgun fitted with a buttstock and a barrel of less than 16 inches length.

no it is not a sbr because the barrel length is 18.1 inches minimum barrel length for a rifle (to not be a SBR) is 16 inches Walther Arms 573030010 HK G36 Semi-Automatic 22 LR 18.1" 10+1 Synthetic Black Stk Black

The HK G36 5.56x45mm rifle was designed in the early 1990s as a replacement
for the heavier 7.62mm G3 battle rifle. It was accepted into service in
German armed forces and is used as an in infantry gun in a large number of
countries. This genuine rimfire replica offers all the excitement of the
original in cost effective .22 L.R. caliber. The HK G36 Semi-Automatic
Rifle in .22 L.R. is manufactured exclusively by Walther under license from
HK. It is the only genuine HK tactical rimfire replica available in the
world.

SPECIFICATIONS:
Mfg Item Num: 573030010
Category: RIFLES CENTERFIRE
Action :Semi-Automatic
Caliber :22 Long Rifle (LR)
Barrel Length :18.1"
Capacity :10+1
Trigger :
Safety :Ambidextrous External Safety
OAL :37.8"
Weight :6.74 lbs
Stock Description :Synthetic Black
Metal Finish :Black
Twist :
Barrel Description :
Muzzle :
Receiver Material :Steel
Sights :Adjustable Rear, Fixed Front
Hand :Right
Stock Finish Group :Synthetic
Metal Finish Group :Blued/Black