Both munitions fail to match the level curve (adjusted for attributes) by a significant amount, and fail to perform as upgrades to the earlier missiles in their range (the 800F CAN be an upgrade, but only if you hit before the failsafe times out). Both should have significant buffs to their fragment damage to bring them back into relevance.
This also applies to a lot of other vanilla fragmentation weapons, but these two are probably the worst.
(NB: This will result in an indirect buff to the Molotok and other enemies using the 800F)
Alternately, increase the number of fragments or area of effect to make them damage more individual targets when attacking grouped targets.
That would work, but has its own problems: lots of little fragments tend to suffer from the armor damage curve (and the 800F uses kinetic damage, which is hardly ideal anyway), and make a mess of the sound mixer. It's definitely an option though.
The way I go about balancing fragments is to look sequentially:
1. Are the fragments hitting the target under normal conditions?
2. Are they reliably able to damage the target when they should be able to?
3. Are they approximating the level curve?
4. Are deviations from the level curve matched by the soft stats of the missile, and do they make sense from the in-universe purpose of the missile?
5. Are there any unusual circumstances that might result in doing excessive or minimal damage? (this is generally caused by bad failsafes or fragmenting fragments coming off a missiles, sometimes also hit detection bugs).
Of those the first two are the most important, the third is important once the first two are sorted, the fourth makes the item not be annoying, and the last is something to watch for once you've got most of the weapon working nicely.
So, the ammo rebalancing (see http://ministry.kronosaur.com/record.hexm?id=2947) increased the WMD and number of fragments of the Black Strelka. I'd expect that to make it at least comparable to the Red.
As for the 800F, would it work for the blast damage to be a radius fragment with comparable range to the kinetic fragments? The KM110 Longbow could maybe also use this.
I changed the 800F to have blast fragments. I said I had done that in a comment, but it looks like I never did. Let me know if it over/under-powered.
I think the Black Strelka is OK now that it has more fragments and WMD.
The 800F already feels overpowered with the downgrade to kinetic, I don't think its a good idea to move to blast fragments without lowering damage.