I finally had a chance to take the new (to me) 6.5mm Jap Type 38 out to the range. However, all did not go well. I shot 5 rounds, then had five consecutive non-fires. All fired rounds had backed-out primers. All non-fires had light firing pin impressions. The ammo is Hornady 6.5 JAP. The head stamp is nny, 6.5 x 51R. My Hornady Loading Manual indicates the 6.5 Jap is 6.5 x 50mm. I brought everything home, and then completely stripped the bolt and gave it a significant cleaning. It had a lot of old powder residue inside the bolt body where the striker pin resides. I suspect this was the cause of the non-fires. I then pulled the bullets and powder from 5 other new bullets, and then fired them (primers only) in the garage. These fired well, with good firing pin impressions, but the primers were also backed out. I then re-sized these cases in a new Lee sizing die, and re-primed them. They also fired well (primers only) with good pin impressions, but also had backed-out primers. I checked the dimensions on the cases of all five rounds that successfully fired at the range. All dimensions seemed to be in spec, and I saw no bulges or increased diameters at the case head. Attached are four photos. The first shows the non-fires (top row with light pin impressions) and the fired rounds are on the lower row. The second photo shows a closer shot of the non-fires. The third photo shows the backed out primers on the rounds actually fired at the range. The fourth photo is the five cases after re-sizing the brass then firing in the garage. Note the primers are still backed out. Is this a case of excess head space and would another bolt possibly solve this problem?