This orbat is from White Guard Almanac #8, citing the Russian Archives (РГВА. Ф. 39514. Оп. 1. Д. 6. Л. 8-10) and found at a-pesni.golosa.info.
This is the army of the Orenburg Host, defending their lands, under their Ataman. However, there was a large amount of exchange of units with the army of Kolchak. This gave the Host access to needed infantry, in exchange for the cavalry that Kolchak's army wanted.
Tatishchevo Plastoon Divizion – 1 company, 127 bayonets
Sakmarskiy Horse Divizion – 3 sotnias, 321 sabres
5th Rifle Division
18th Orenburg Rifle Regiment – 1 battalion, 77 men, 5 MGs
19th Orenburg Rifle Regiment – 1 battalion, 138 men, 4 MGs
20th Orenburg Rifle Regiment – 36 men, 7 MGs
21th Orenburg Rifle Regiment – 1 battalion, 68 men, 5 MGs
9th Bashkir Rifle Division
This brigade defected soon afterwards.
37th Bashkir Rifle Regiment – 1 battalion, 467 bayonets, 33 sabres, 15 MGs
38th Bashkir Rifle Regiment – 1 battalion, 330 bayonets, 73 sabres, 10 MGs
39th Bashkir Rifle Regiment – 1 battalion, 420 bayonets, 14 MGs
40th Bashkir Rifle Regiment – 1 battalion, 368 bayonets, 10 MGs
4th Bashkir battery – 2 guns (3")
Attached to Northern Sector
9th Orenburg Cossack Regiment – 6 sotnias, 1084 sabres, 9 MGs
23rd Orenburg Cossack Regiment – 3 sotnias, 712 sabres, 4 MGs
Militia Horse Sotnia – 78 sabres
3rd Battery of the 5th Rifle Artillery Brigade – 3 guns (37 mm)
2nd Rifle Division
5th Syzran Rifle Regiment – 3 battalions, 506 bayonets, 16 MGs
6th Syzran Rifle Regiment – 1 battalion, 217 bayonets, 11 MGs
7th Khvalinsk Rifle Regiment – 1 battalion, 240 bayonets, 5 MGs
8th Volga Rifle Regiment – 2 battalions, 578 bayonets, 13 MGs
2nd Syzran Cavalry Regiment – 4 sotnias, 280 sabres, 4 MGs
6th Battery of 2nd Rifle Artillery Brigade – 3 guns (3")
4th Orenburg Cossack Division
19th Orenburg Cossack Regiment – 6 sotnias, 572 sabres, 13 MGs
20th Orenburg Cossack Regiment – 6 sotnias, 820 sabres, 7 MGs
24th Orenburg Cossack Regiment – 6 sotnias, 840 sabres, 8 MGs
25th Orenburg Cossack Regiment – 6 sotnias, 775 sabres, 9 MGs
4th Orenburg Cossack Artillery Divizion
11th Orenburg Cossack Battery – 2 guns (3")
12th Orenburg Cossack Battery – 4 guns (3")
Attached to the Sector
Ataman's Divizion of the Orenburg Cossack Host – 2 sotnias, 326 sabres, 6 MGs
4th Battery of 2 Rifle Artillery Brigade – 2 guns (3")
3rd Battery of 2nd Heavy Artillery Divizion – 2 guns (107 mm)
Plastoon Heavy Artillery – 2 guns (6")
Syzran Engineer Company – 35 bayonets, 5 sabres
Armoured Train – 1 gun (3")
1st Orenburg Cossack Division
1st Line Cossack Regiment – 6 sotnias, 629 sabres, 8 MGs
8th Orenburg Cossack Regiment – 6 sotnias, 723 sabres, 4 MGs
13th Orenburg Cossack Regiment – 6 sotnias, 630 sabres, 9 MGs
Plastoon Divizion – 3 companies, 206 bayonets
Separate Line Plastoon Sotnia – 1 company, 73 bayonets
1st Orenburg Artillery Divizion
1st Orenburg Cossack Battery – 4 guns (3")
4th Orenburg Cossack Battery – 4 guns (3")
10th Orenburg Cossack Battery – 3 guns (3")
2nd Orenburg Cossack Division (part only)
10th Orenburg Cossack Regiment – 6 sotnias, 731 sabres, 2 MGs
15th Orenburg Cossack Regiment – 9 sotnias, 661 sabres, 6 MGs
16th Orenburg Cossack Regiment – 6 sotnias, 804 sabres, 9 MGs
11th Buzuluk Rifle Regiment – 3 battalions, 350 bayonets, 24 MGs
7th Orenburg Cossack Battery – 4 guns (3")
Attached to the Corps
1st Orenburg Cossack Regiment – 6 sotnias, 721 sabres, 12 MGs
1st Orenburg Plastoon Regiment – 9 companies, 770 bayonets, 11 MGs
Ataman Regiment – 161 bayonets
Steppe Partisan Detachment – 199 bayonets
1st Reconnaissance Sotnia – 163 sabres
2nd Reconnaissance Sotnia – 235 sabres
6th Sakmarsk Horse Sotnia – (communications unit)
2 Sotnias of 1st Reserve Divizion – 2 sotnias, 73 bayonets, 150 sabres
Special Task Force, Cossacks of Ugol' and Grigorievsk Villages – 110 bayonets, 104 sabres, 3 MGs
Howitzer Battery – 4 guns (122 mm)
Heavy Gun Battery of Divizion of Staff-Captain Nosarev – 3 guns (107 mm)
Plastoon Light Battery – 1 gun (3")
42-Line Battery Platoon – 2 guns (107 mm = 42-line)
1st Battery of 2nd Heavy Artillery Divizion – 4 guns (152mm)
Armoured train – 1 gun (3")
21st Orenburg Cossack Regiment – 6 sotnias, 774 sabres, 6 MGs
Light Gun Battery of Artillery Divizion of Staff-Captain Nosarev – 2 guns (3")
14th Orenburg Cossack Regiment – 6 sotnias, 673 sabres, 17 MGs
Berdsk Horse Sotnia – 105 sabres
Escort Sotnia to the Commander of the Army – 62 sabres, 4 MGs
Aviation Group of the Separate Orenburg Army – 5 planes + 2 faulty
1st Separate Sotnia of the Orenburg Host – 108 sabres
The total forces above add up to almost 6,000 bayonets, 13,000 sabres, 319 MGs and 53 guns. However, this includes the Bashkir Brigade, the bulk of which was already unreliable and soon to defect. The actual operating total is therefore about 4,500 bayonets, 13,000 sabres, 270 MGs and 50 guns.
From V.F. Vorob'ev "The Defence of Orenburg", citing the Archives of the October Revolution, the total for the Separate Orenburg Army on 15 May 1919 is given as:
11 battalions
74 sotnias
395 officers
4,628 bayonets
10,054 sabres
528 artillerymen
127 machine-guns (25 Maxims, 63 Colts, 39 Lewis)
14 artillery pieces