Interesting to reread this thread. The beatdown of the strawman brothers was merciless. There are a couple of options here:
1) Buell and his sister made up the long bag story. Oswald told the truth that he carried only his lunch sack.
Problems: no logical explanation for Buell and his sister to intentionally lie about Oswald carrying a long bag and the curtain rod story. If anything, this makes Buell look like he might have some reason to be suspicious of a guy making an unexpected trip and carrying a long, rifle shaped bag to his workplace on the morning that the president was going to drive by his building. A bag would also have to be planted and Oswald's prints somehow added to it. Odds of this scenario = zero.
2) Oswald carried a long bag along the size estimated by Buell.
Problems: Oswald denied this. If this long bag had contained something exculpatory, then Oswald would have had every incentive to direct the DPD to his bag. He didn't. No bag matching Buell's estimate was ever found or otherwise accounted for in the TSBD. The longer bag would have to be planted etc. Odds of this = near zero.
3) Oswald carried the long bag found on the 6th floor. His prints are on that bag, it is found next to the SN where Oswald's prints were found along with fired bullet casings from his rifle. There is no other accounting for that bag being on the 6th floor except in association with the assassination.
Problems: Oswald denied carrying such a bag. But he has every reason to lie if it contained the rifle. Buell and his sister indicated the bag was too short to contain the rifle. But they didn't have a great look or any reason to take much notice. They made an honest but erroneous estimate. The bag itself is the best evidence of its length. Odds = 99.99 percent that the bag found on the 6th floor is the one Oswald carried to work that morning.
Richard,
1) LHO's lunch sack may have been the sack described by Buell and his sister. Oswald was poor, staying at some else house. He would have grabbed anything available to reuse. As I have previously pointed out, the sack may have been one that orignally contained curtain rods, which Oswald reused for his lunch. When asked about the lunch sack, he may have responded to Buell with an answer as to its origins (explaining the unusual length) not its current contents.
2) Beull saw the bag on multile occassions, not a single glance. Oswald waited, not far from he car, whilst Buell charged the battery and only proceeded to the TSBD once Buell was on his way. Buell description of Oswald's method of carying the bag does not match either a longer bag nor a bag with the elongated weight distribution of a hidden rifle.
3) You ignored the failure of the DPD to photograph the bag in situ at the crime scene, along with the failure of the earliest DPD members to notice the bag. Surely that warrants a greater degree of uncertainty greater than the 0.01% that you have speculated.