I've been bitten by the 1919 belt-fed bug and have been researching what I want to buy for about 3 months. For anyone interested in getting into semi-auto Browning 1919 ownership, I thought you may like some tips on what I've learned from my research.
Here ya go:
--Browning 1919 semi-auto
From $1200 to $2400. The cheaper guns usually have issues and shoddy quality. If you don't mind sending a gun back for repair a few times and replacing parts every 500-1000 rounds, then the $1200 gun is for you. The high quality guns (about $2000) from TNW, Black-Bear and Ohio Ordinance have the best reputation, with Black Bear being the most highly regarded. Some owners are reporting 40,000 round through their Black Bear without any issues or parts breakage at all. Black Bear guns also reportedly have perfect welds and rivets exactly like GI guns. Most all the guns are made from Israeli .308 1919A4 parts kits.
--Caliber
Guns are available in 30.06, .308 and 8mm. Caliber can be easily changed on the high-quality guns by changing the barrel, recoil booster, cartridge stops and rear feed guide in the feed mechanism. Some of the cheaper guns weld the rear feed guide in place, which forces you to start cutting metal to change calibers.
8mm
Many shooters love the 8mm variant because the ammo is really cheap (about $100 or less per 1000), but all the surplus ammo is corrosive and this makes the gun a bitch to clean. Alot of the 8mm surplus ammo on the market is garbage from the 40's and 50's, and may blowup your gun. Select ammo carefully. Most of the 8mm barrels available are aftermarket, so it's a crap-shoot on barrel quality. If you like to shoot 1000's of rounds a year, the 8mm is probably the best choice. Barrels run about $150.
.308
.308 seems to be the best choice for the occasional shooter and is the caliber I selected. With .308 you have original Israeli IMI 98% condition barrels that can be purchased for about $60 each. Ammo is mostly non-corrosive and can be bought for about $150 per thousand.
30.06
Hardly anyone goes with 30.06 due to the price of ammo.
Important note about ammo: Low quality ammo can do serious damage to your gun. Whenever purchasing surplus ammunition, always verify the quality before purchasing. Posting a question on a gun message-board about the ammo in question is usually sufficient enough to get some insight from other users into the quality of the ammo.
--Belts/Links, Linkers and Loaders
The Israelis designed their 1919 to run on disintegrating belts. These Israeli 1919 links can be purchased for $70 per 1000 and are available in new/unused condition (M60 links won't work in the 1919). The Israeli 1919 links work with all three calibers. If you go with links, you'll need a "Linker". A Linker is a device that you put 10-20 links and 10-20 rounds into a tray, and pull a lever to push the rounds into the links. These go for about $100-265. The $265 units are made from real US GI Issue .50 cal linkers that have been modified to work with .308/8mm/30.06. These will last a lifetime. The other units are aftermarket and quality varies. However, most people report that the $185 aftermarket unit from Ohio Ordinance works really well. Some units you have to change the tray plate in the linker to change calibers (extra cost). Other units will load all three calibers.
If you're using links, it's probably a good idea to purchase a "trunnion protector" to protect the trunnion feed-way from wear/scaring. The trunnion protector keeps the links from directly rubbing on the feed-way. They snap-on and cost about $14 from Guiette Mfg. http://www.guiettemfg.com/catalog.html
You can also use cloth belts. Cloth belts run about $15-30 each (most are 100 or 250 round). No change of parts is required to go from links to cloth belts. Cloth belts tend to be a little more finicky, as rounds tend to shift around and fall out of the cloth belt. Cloth belts can be hand-loaded, but owners report this as being very tedious and painful to the fingers. You really need a "GI Issue 1918 belt loader" if you want to use cloth belts, and these go for around $1000-$1200 and only work with 30.06 & 8mm (after-market conversions to .308 are available). The only real advantage to the cloth belt is you don't have to pick up links when you're done. Most people agree that links are the way to go due to the high cost of a 1918 belt loader.
--Tripods
There are numerous options here. The M2 tripod is original to the 1919 (WWII era). Original US GI Issue units go for between $550 and $850 (depending on markings and condition). This includes the T&E and pintle. There are aftermarket copies of the M2 that go for around $400-$550. The original GI Issue M2 has nice looking reference numbers on the adjustments for the transverse mechanism, most aftermarket M2 tripod are unmarked.
If you want a full size tripod, there are numerous aftermarket adapters to mate a 1919 to a MG3 tripod, Bren tripod or a MAG58 tripod. You're talking 40-70 lbs for these bad boys, unless you're lucky enough to find a titanium MAG58 tripod. The MG3 surplus tripods can be found in near new condition with awesome optics and remote firing for about $650. If you really want to go vintage, you can go with a WWI era 1917 tripod at around $1000-$1500. I think these weigh about 90 lbs or so.
You can order your 1919 in the A6 configuration (shoulder stock, carrying handle and bi-pod) and avoid a tripod altogether.
There you have it. That's some of the important highlights of what that I've learned from reading 1000's of posts about owning 1919's.
In case you're interested on the final choices that I made, I went with the Black Bear 1919A4 .308 with Ohio Ordinance Spade grips, a refinished WWII era 1942 marked M2 GI Issue tripod (http://www.coledistributing.com/ ), the Guiette Linker ( http://www.guiettemfg.com/catalog.html ), and 2000 links from Ohio Ordinance ( http://www.ohioordnanceworks.com/index.htm )
For reference, here is the 1919 forum: http://www.1919a4.com/