I have a pair of first gen Senderos here. One is in 338 RUM, the other in 300 RUM. The 300 has a recessed crown, whereas the 338 is tapered. I believe the 338 is correct, but did Remington change these up at some point. Neither look to have been shot much, or mollested at any point. Both carry the J-lock, so build time should be relatively close. The 300 barrel also looks to be about 1/4" to 3/8" shorter than the 338. Normally, I would think that a smith was trying to fix a factory problem with a poor shooter, but the bolt face shows little to no sign of being shot. If need be, I can post a pic of them.