iloco- The main difference is in the barrels. Bridger's rifle has a barrel 33 1/4" long ahead of the snail. It measures 1.175 at the breech and 1.125 at the muzzle, which is not a tapered barrel. Carl Walker of the Green River Rifle Works who made copies of it said you could make that much difference with a file. That is .050 slimming, half the thickness of a dime per side in 33 1/4 inches. The Carson rifle I have not yet handled, I hope to do so in the spring, but I understand it has a straight 1" barrel a little over 31" long. Track's parts for it are a 1" barrel, and a 1 1/8" for the Bridger. The Bridger and Carson rifles are fraternal twins, nearly alike. The butt plates are the same to my eye, and Track's BP-Hawk-JB-I is the nearest correct commercially available, once the inside corner is filed square. I think this same one is correct for the Carson rifle, with square corner. I used this on my Bridger copy, but in comparing my rifle to Bridger's in the Montana museum, I discovered the tang was longer on Jim's, 2.4" inside compared to 1.625 on Track's. If I ever make another copy, I'll cut the tang off one butt plate and weld it on the other as an extension. Here is my Bridger copy and Jim's rifle in the Montana State Historical Society Museum in Helena, MT. Note the curl of the rear trigger guard loop.
The Bridger butt plate and cheek piece. The toe plate is riveted to the butt plate.
The photo of the Bridger rifle was taken by my friend Dave Boender in 1975 when GRRW had the rifle for making copies. I enlarged it to full size, based on a 4.85" long Bridger lock, but the original I measured at 5.0". Track's trigger guard TG-Hawk-L-I is the correct one. There is a difference in the rear loop, Track's tail is longer than Jim's. I have since cut mine off to the white line, and it is a very close match. The triggers have a different spacing, nothing to do about that. My triggers are Ron Long's #TR-PA-20.
Here you can see the trigger spacing.
Track's entry pipe for the Bridger is wrong, they have RP-Hawk-E-7-I, but the correct one is RP-Hawk-TE-7-I, which they correctly use for their Carson rifle. The Bridger rod pipes are 1/2" inside, including the entry pipe. I drilled the cast RP-Hawk-TE-7-I out to .500" and made my ram rod 1/2" full length.
I bought Track's new Kit Carson's Hawken Rifle full scale plan drawing and it is a fantasy thing in my opinion. The length of pull is a God-awful 14 5/8", whereas Carson's rifle is really about 13 1/2" (I have not personally measured it, but scaled it from photos). The barrel is too long at 34.4" and the butt plate is not correct. But they used to have a plan for the Bridger Hawken that was good, I don't see it in Catalog #18. Bridger's rifle has a 13 1/4" length of pull, weighs 11 pounds 4 ounces, my copy has a GRRW 1 1/8" barrel 31" ahead of the snail (2 1/4" shorter than Jim's) and weighs 10 pounds 12 ounces. And I can shoot it. At Jim Goodman's New Years shoot (posted here under black powder shooting) I "killed" all 17 targets, which I personally had not seen done in 100 to 150 scores over 8 to a dozen trail walks there.