The problem with Custer's defeat was NOT that the Indians had Winchesters with 8-9 shoots in a Tubular magazine. The problem was the sheer number of Indians involved. Remember Custer attacked the largest collection of Plain Tribes even known to occur.
The problem with Tubular magazine is it is almost impossible to reload rapidly. Thus after you fired your 8-9 shots you are stuck with a single shot rifle, and that is when Custer lost his battle, not in the first 8-9 rounds but the constant attacks that overwhelmed his forces. Military weapons of the 1880s that did use Tubular Magazines, but like the last model of the Spencer carbine issued at the end of the Civil War, had mechanism to keep those rounds in reserve, till you actually needed them (Winchester did NOT have that feature, but those Military rifles that had Tubular magazines almost always did).
Thus in Wounded Knee the Troops of the Seventh Calvary just kept on firing round after round killing the Indians (Wounded Knee is called a Massacre for the number of Indians killed by single shot Springfields). Reno, whose had command over three Troops of the Seventh when Custer was Killed, kept his troops alive by retreating into an area with woods then rocks where he could set up a defensive perimeter. He and his men survived, Custer attacking from a different direction with 5 Troops of the Seventh ended up having to retreat to an open area, with no natural protection. The troops with Custer were quickly overrun probably by Indians armed with bow and arrows, muzzle-loading rifles, and maybe some Winchesters but NOT many (Winchesters were expensive and rare in the West, Buffalo Bill Cody was one of the few people with one, more as a publicity act by Winchester then anything else). The 1866 and 1873 Winchesters fired a round barely more powerful then a pistol round. Thus of limited usability in the battle. Those troopers who did buy their own rifles tended to Sharps NOT Winchesters.
My point is simple, the difference between the single shot Springfields and the Winchester the Indians May have had (and I have my doubts to more then just a couple) does NOT explain Custer's defeat. The reason for the Defeat was that Custer attacked the largest collection of Plain Indians even known to occur. Custer was overwhelmed by sheer numbers NOT superior firepower.
Side Note: Not only were the 1866, 1873 and 1876 Winchester firing weaker rounds then the 45-70 the Army was using, they were expensive. In 1880 Merlin came out with his lever action, cheaper, stronger, more reliable then the Winchesters mentioned above. Winchester then contacted Browning who designed the 1886 Winchester. The 1886 was cheaper, stronger and more reliable then the older Winchester AND capable of firing 45-70 ammunition. The Model 1886 was a complete redesign, except for the lever itself the 1886 had NOTHING to do with the earlier Winchesters (The feed mechanism was the same was the model 1873 and 1876 but updated). The Model 1886 lead to the model 1892 (To replace the Model 1873) and 1894 (to fire smokeless ammunition like the 30-30). Winchester only became the top weapon in the US with the model 1886, its earlier models were more expensive toys then weapons real people used. The Model 1866, 1873 and 1876 did sell and sell well, but was secondary to Winchesters own single shot rifles and even the Remington Rolling Block. My point is even the Indians preferred the single shot rifles then the rapid fire rifles like the Winchesters. Until the Lee Magazine was invented there was no way to have a rapid shooting rifle for more then a few seconds (I.e. Reloading the rifle is more important then how fast you can shoot the weapon). With the Lee Magazine you could load 5-10 rounds at a time. Later on the Lee was modified to be removable, which produced the present large magazine rifles. The Lee was NOT invented till the 1880s, Mauser modified it to permit loading by five round "Stripper clips" that increased overall fire to about 14 rounds a minute (1890s) then to semi-automatic M1 during WWII then detachable clips during WWII and afterward.
Second Side Note: A problem that did occur was the US Army had gone cheap, instead of using Brass Cartridges, the Army had gone to Copper. Copper is NOT as flexible as Brass but cheaper. The lack of flexibility meant the copper cartridges would jam in the action (Brass being more flexible, would NOT). There is reports that rifles where found with copper cartridges stuck in the rifle. The problem with copper cartridges were well know BEFORE his defeat, thus Custer and his officers tended to buy Brass Cartridges for their own use, but their men had to use the Army Copper issued Rounds.
In Fetterman's defeat ten years before Custer, the Indians used only Bows and Arrows:
http://en.wikipedia.org/wiki/William_J._Fettermanhttp://en.wikipedia.org/wiki/Fetterman_Massacre