Barnual is sold under the names Monarch and Ram. They're marked differently but they're all made by Barnual.
Both Barnual and Wolf have the airspace in the tip. The early imported Uly 5.45 did not have the airspace. Wolf HP shouldn't be a problem with feeding, as its the same length as the FMJ bullet.
Barnaul 5.45 HP is shorter and gets caught on the bullet guide/feed ramp sometimes. The 5.45 SP is said to be really inaccurate at 100 yds.
The Dynamit Nobel 5.45mm is HP but really expensive. $30 for 50 rds. It's said to be the most accurate 5.45mm avaliable.
5.45mm was designed to yaw after 2.75 inches of penetration. Then at 11 inches yawing again and with a total penetration of 20 inches, at the last few inches of its path takes a 90 degree turn.
The yawing isn't velocity dependent like the fragmentation of 5.56mm.