If I'm understanding you correctly, your saying this is new unfired brass straight from the factory bag that has not been sized. It's obvious to me that you have a neck tension problem.
First of all I would recommend FL sizing and chamfering all new brass just to be able to start with a known condition for the brass. This will eliminate variations and inconsistency that may have been introduced in manufacturing. You will also get a feel for how tight your expander ball is during the sizing operation. If you feel little or no resistance as the expander is pushed into the neck or when it is withdrawn from the case neck, you should be wondering why. Cases that seem very hard to withdraw form the die could indicate an oversize expander. If your using a die that has not had this problem previously the problem is more likely the brass. If you happen to get a case lot that has thin neck wall thickness or the necks are unusually hard you may find it difficult to get enough neck tension to hold the bullet.
FL resize a few of the problem cases, seat a few bullets in these unprimed cases, and check neck tension by pushing the bullet nose firmly against a wooden block. You can further test them by seating them in chamber stripped from the magazine to see if they move. Check the OAL before and after chambering to see if they got longer.
Measure the neck wall thickness compared to others of a different headstamp to see if they are much thinner. If this is the case, call the manufacturer and see if you can get them replaced. I have run across 2 bags of Winchester .223 Rem brass that was defective in this way and it was replaced. Annealing could solve the problem if it's just too brittle but I would not put up with having to do that to new brass.
Crimping is not a good alternative to proper neck tension.
The OAL you quoted for that bullet is not too long so I can't see that as the problem. It is far more likely the bullet is sliding forward during chambering and sticking in the lands. (After further research, the 55 grain Hornady SP might engage the lands with a COL of 2.250. The Wylde chamber is supposed to be slightly longer in the throat so you'll have to check to be sure.)
