Ivan But was born in 1915.

When Germany invaded the Soviet Union on 22 June 1941, mladshiy leitenant But served in 147 IAP, which was equipped with Polikarpov I-153s.

He was posted from 147 IAP in February 1942 when he was posted to 145 IAP.

But claimed a shared Hs 126 ”in group” on 23 February. It’s possible that Vladimir Mironenko also took part in this claim since it’s known that he also claimed a Hs 126 ”in group” during the day.
According to Luftwaffe records, no Hs 126 were lost in the Karelian region during the day.

On 4 April 1942, 145 IAP became a guard’s unit and was renamed to 19 GIAP.

In April, he was posted to 20 GIAP.

On 23 April, kapitan Aleksei Khlobystov claimed six shared enemy aircraft (1 Bf 110, 2 Bf 109s and 3 Ju 87s) over Lake Pyayve-Yavr together with starshiy leitenant Adam Kontsevoy, starshiy leitenant But (Hurricane), starshiy leitenant Dmitriy Gorelysev, mladshiy serzhant Mikhail Bychkov, serzhant A. I. Chibisov, serzhant Petelin and serzhant Zurov.
Starshiy leitenant But and serzhant Chibisov were both shot down and killed during the day.

At the time of his death, But was credited with 1 biplane victory.
This had been claimed in 56 combat missions (as of 20 September 1941).

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1941
1	13/09/41		1	Bf 109	Destroyed	I-153		Karelian Front	147 IAP
	1942
	19/02/42		1/?	Bf 109	Shared destroyed	Hurricane		Karelian Front	145 IAP
	19/02/42		1/?	Bf 109	Shared destroyed	Hurricane		Karelian Front	145 IAP
	23/02/42		1/?	Hs 126 (a)	Shared destroyed	Hurricane		Karelian Front	145 IAP
	26/02/42		1/?	Bf 109	Shared destroyed	Hurricane		Karelian Front	145 IAP
	23/04/42		1/8	Bf 109	Shared destroyed	Hurricane		Lake Pyayve-Yavr	20 GIAP
	23/04/42		1/8	Bf 109	Shared destroyed	Hurricane		Lake Pyayve-Yavr	20 GIAP
	23/04/42		1/8	Bf 110	Shared destroyed	Hurricane		Lake Pyayve-Yavr	20 GIAP
	23/04/42		1/8	Ju 87	Shared destroyed	Hurricane		Lake Pyayve-Yavr	20 GIAP
	23/04/42		1/8	Ju 87	Shared destroyed	Hurricane		Lake Pyayve-Yavr	20 GIAP
	23/04/42		1/8	Ju 87	Shared destroyed	Hurricane		Lake Pyayve-Yavr	20 GIAP

Biplane victories: 1 destroyed.
TOTAL: 1 and 10 shared destroyed.
(a) Not verified with Luftwaffe records.

Sources:
All aces of Stalin 1936-1953 – Mikhail Bykov, 2014
Soviet Aces 1936-1953
Soviet Fighter Pilots 1936-1953 - Mikhail Bykov