Can a Winchester Magazine be Modified to Have a Larger Capacity?

[SPJ]

I am looking into buying either a a Winchester 1866 or 1873 in 38 Special, and I found something that confuses me. Uberti's website lists their 18 inch barreled version of the 1873 as having the same magazine capacity as their 20 inch barreled rifle, 10 rounds of .357 magnum +1 in the chamber, or 11+1 rounds of .38 spcl as other dealer websites will say. This doesn't make sense though because a longer barrel should mean a longer magazine, and thus a greater capacity. Especially when I have read other sources stating that the original 20 inch Winchester 1873 carbine had a capacity of 12 .44-40 cartridges. So why does the Uberti replica at 20 inches not have a larger capacity, is this for legal reasons I am unaware of, and can it be modified?

If this can be altered, and if someone has done so already, can anyone tell me what the max capacity of a 20" barreled Winchester can be when loaded with .38 Special cartridges of 1.425" OAL? I'd like to know because I also want a converted Colt 1851 that I can use the same cartridges in as the Winchester.

Thank you

https://www.uberti-usa.com/1873-rifle-and-carbine

[wildman1]

The Uberti 73's or 66's can be modified by trimming the mag spring to allow more cartridges to fit. Start by trimming a few coils at a time until you reach the desired capacity. I have a 16" 73 that will hold 10 357 magnum cartridges. It is a tight fit but it works. Also clean the spring, mag tuibe and make sure the follower is polished a little so it does not have any burrs on it. The minimum spring length recommended is to have 3" extending with the spring at rest in the mag tube without the end cap installed.
wM1

[Coffinmaker]

First, don't believe everything you read from the Importers.  They often speak in generalities.  The only accurate way to answer your question(s) would be to load a batch of dummies to your specified dimensions and stuff 'em inna rifle and count.  Then modify the OEM spring and do it again.

However.  Any and ALL 18, 19 and 20 inch 1873 replicas will hold at a minimum of 10 rounds for CAS game play.  Anything over that would be considered "Cake."  Buy a Rifle and see whatcha get     

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[SPJ]

The Uberti 73's or 66's can be modified by trimming the mag spring to allow more cartridges to fit. Start by trimming a few coils at a time until you reach the desired capacity. I have a 16" 73 that will hold 10 357 magnum cartridges. It is a tight fit but it works. Also clean the spring, mag tuibe and make sure the follower is polished a little so it does not have any burrs on it. The minimum spring length recommended is to have 3" extending with the spring at rest in the mag tube without the end cap installed.
wM1

Thank you. That makes sense. I figure that with tube magazines you would only require about 1 cartridge length of space for the compressed spring and follower. So in my mind your gun must hold 15 rounds in the mag and one on the cartridge carrier. If that is the case then, and I were to use 38 spls of avereg length at roughly 1.55 inches, then I could make a gun with a 20" mag would hold 13 cartridges. 12 in the mag and 1 on the cartridge carrier. Am I wrong in thinking that?

[Abilene]

Probably right.  Springs vary.  .38's will actually zigzag a little which gives a tad more room maybe?  The mag tube cap takes up a little space.  That cap is hollowed out on my 16" trapper, and along with a specially tapered spring that collapses inside itself on both ends lets it hold 10 (like Wildman1's, but mine is.45 Colt).  You could hollow out your end cap if you need just a wee bit more.  Bear in mind that rifles that are loaded to absolute maximum will be pushing hard on the first round on the carrier, which will be at an angle.  There is a bevel in the frame that should keep the edge of the rim from catching on the way up, but it can cause a hitch.  On my trapper that first round was so tight I had to reach a knife blade down the top of the carrier to straighten the round or it wouldn't lever.  I have since switched to shooting Schofields in it and ten will both load and cycle easier due to a bit more room in the mag.

[SPJ]

Probably right.  Springs vary.  .38's will actually zigzag a little which gives a tad more room maybe?  The mag tube cap takes up a little space.  That cap is hollowed out on my 16" trapper, and along with a specially tapered spring that collapses inside itself on both ends lets it hold 10 (like Wildman1's, but mine is.45 Colt).  You could hollow out your end cap if you need just a wee bit more.  Bear in mind that rifles that are loaded to absolute maximum will be pushing hard on the first round on the carrier, which will be at an angle.  There is a bevel in the frame that should keep the edge of the rim from catching on the way up, but it can cause a hitch.  On my trapper that first round was so tight I had to reach a knife blade down the top of the carrier to straighten the round or it wouldn't lever.  I have since switched to shooting Schofields in it and ten will both load and cycle easier due to a bit more room in the mag.

Okay, if that is the case then I may not go for maximum capacity if the mag spring does need some free space. Does that type of tapering spring have a specific name? Where would I find one?

[Abilene]

Okay, if that is the case then I may not go for maximum capacity if the mag spring does need some free space. Does that type of tapering spring have a specific name? Where would I find one?

The spring and hollow mag cap were proprietary parts made for Cimarron by Uberti.  Although I heard of one person ordering those parts and getting them from Cimarron years ago, I think they are generally not available.   I was a part-timer for Cimarron for a long time and never saw one of those springs in stock.  You could call them and/or VTI and ask.  The mag cap could be hollowed out by a machinist.

[Coffinmaker]

Abilene is correct.  The hollow magazine End Cap and the special double taper magazine Spring are Proprietary Cimarron parts supplied specifically for the 16 inch barrel Trappers Cimarron carries. 

When I was building my 1866 and 1873 Trappers, Cimarron would not sell those parts no matter how hard I tried.  If you claimed something broken, Cimarron wanted the Gun to repair.  I still built my Trappers, however since I am shooting .45s, I elected to use the modified Carrier Blocks from Adirondack Jack.  Those carriers are now available from The Smith Shop.  Used my own Proprietary cartridge, The 45 Squirt.  Made from 45 Schofield.  Switched to Cowboy 45 Special to save the labor of making my own short cases to get 10 in my Trappers.  Including my 16 inch barrel Henry Trapper. 

[wildman1]

The only one that is actually difficult to get the spring right is the 16" one. The rest are pretty easy.
wM1