Anybody adjusted point of impact on double barrel rifle, 9,3x74 R O/U, with adjustable barrels, using lighter bullets?

Some background first: As a kid, I was always dreaming about Brno Super Model 575, double barrel rifle. Well, not as refined as some comparable Austrian or German rifles, but it is quite strong and robust, with double Kersten locks and Pardey uderbites, and H&H style sidelocks. And the best part is, with all those goodies, Brno Supper was considerably less expensive than Austrian or German rifles.

I had seen few times Brno Super double barrel 575.1 in 7x65R, but since I hunt almost exclusively wild boars, I always felt that bigger caliber is better.

Next model in larger caliber is 575.2, chambered in 9,3x74 R, but what turned me off was ammo with heavy bullets, as required for tropical big game. And recoil that goes with such loads, plus not so flat trajectory because of lower muzzle velocity. Regarding recoil, I can shoot 338 WM with 250 grains bullet, but it doesn't mean that I like and enjoy it.

So, as for 9,3x74 R, I didn't see point of using ammunition with such heavy bullets on wild boars. Yeah, I've heard about some lighter bullets available for handloaders, but the problem is all those bit older double barrel rifles are regulated for heavy bullets. On top of that, I was told (right or wrong, no personal experience) that correct sequence is to fire lower barrel first, and several seconds after, upper barrel, in order to get bullets in the right spot. But, all that is pointless if lighter bullets are used, because points of impact will change considerably. The only way to correct this problem is to send rifle and ammunition to the factory so they will re-regulate barrels for specific load(s). Again, I am just repeating what I found in literature.

Then, two things happened that changed my fairly reserved view on Brno Super 575.2 in 9,3x74 R; I just learned that noted rifle in final years was available with possibility of regulating barrels. Also, I found that RWS is loading 9,3x74R using 11,9 grams (184 grains) bullet, lunched at 885 m/s (2903 fps), see https://rws-ammunition.com/en/...5304bfccc7d96e2f0c25 . But, that is not all! If you go on the chart, you will se that when zero point is adjusted on 179 meters, point of impact on 100 m is +4 cm, on 200 m is -2,9 cm. And velocity on 200 m is still 695 m/s (2280 fps), with energy 2874 J (2120 fp). If you compare this load with any load for 308 Winchester or 30-06 https://rws-ammunition.com/en/...artridges#filterForm , you will see that RWS 9,3x74 R and 11,9 grams bullet has small edge. Plus, it is considerably bigger caliber. Of course, the way bullets are made has significant effect, but I don't have any doubt that noted load for 9,3x74 R is more than enough for wild boars, even on 200 m.


I would appreciate if somebody could explain to me:

- Double barrel rifles with adjustable barrels (Brno Super in particular), do they still keep same point of impact even when one barrel is hot and another cold?

- Would be possible to adjust barrels and get group with both barrels something like 10 cm (4") on 150 m (164 yds), assuming that load is tailored for specific rifle?

Thank you for any info!

The last pig I shot was with a 286-grain bullet from a 9.3x62, the rimless equivalent of the 9.3x74. The result was excellent and I have not for a moment wished for a lighter bullet.

Most db rifles give different results if not fired consecutively.

If you have bought the rifle, go out to the range and fire it with, say, 232-grain bullets and see what happens. Fire the upper barrel within 12 seconds of the first, as British makers would do.

You may find the barrels shoot close enough together at 25 or 50 yards but separate vertically at longer ranges, after which you might keep the higher-shooting barrel for long range, if you can choose which to shoot.

If the result is unsatifactory, you might need to try the heavy bullets and learn to love them, or vary the light loads by reloading - or resort to re-regulation.

I have not seen the Brno set-up but, if it is user-adjustable, go for it. Double rifles are rarely tack-holers but, if you work at it, the results should be good enough.

PS: reading your post again, Onty, I realise you are hunting real European boar, not something else, somewhere else. Your boar are the real deal and not to be underestimated. I recall reading a book by a hunter who used a 4-bore double rifle rifle for them in 1900 and did not admit to being overgunned. So, see which of the heavier bullets regulates best and go with that.

Perhaps get a more-experienced shooter to sight it in for you, to save you developing a flinch. You won't feel a thing when shooting boar.

Picture is not the best quality, but barrel assembly end could be seen.

BTW, very nice stock, with uniform serrations, and no those white spacers.

I know for hunter in Canada, he had on of those German double barrel O/U in 9,3x74 R. I was told that with right load and correct firing sequence, noted rifle will make 10 cm (4") on 100 m, with both barrels, any time.

That 4" group should be possible, if you get the barrels shooting together by one means or another. The barrels do look to have some adjustment means, but I can't be sure.

PS: Onty, you could ask on the AR double-rifle forum, that's where you'll get some real action.