Brno Super Express 7x65R (575.1)

[Daniel Johansson]

Hi all experts on Doubles and oldtimers.

I have bought a Brno and looking for the right bullet/ammo.
I have tried

Sako 170gn
S&B 173gn
Norma 156gn

Everyone are "cross" shooting upper barrel are approx 50cm low. (50m shooting distance)
Any idea what ammo i should use? Im thinking about RWS but what bullet weight? I belive my gun was built 1978!



//Danilj

 

[AZDAVE]

I have been looking at a brno in that cal also, where did you purchase your rifle? I am looking forward seeing what works for you.

 

[Daniel Johansson]

I have been looking at a brno in that cal also, where did you purchase your rifle? I am looking forward seeing what works for you.

Northern Sweden

Im planing to use it on boar hunts, im usally hunting with my dog. So a cheap rugged Doble seems perfect. I have a meopta meosight iii on top of it.

So now i only need to find the right bullet so i can use it instead of my old 375h&h. (great rifle ut to long for the bush)

//Danielj

 

[IvW]

Hi all experts on Doubles and oldtimers.

I have bought a Brno and looking for the right bullet/ammo.
I have tried

Sako 170gn
S&B 173gn
Norma 156gn

Everyone are "cross" shooting upper barrel are approx 50cm low. (50m shooting distance)
Any idea what ammo i should use? Im thinking about RWS but what bullet weight? I belive my gun was built 1978!



//Danilj

50cm low at 50 meters???....I think you have bigger problems than ammo.....

 

[Daniel Johansson]

50cm low at 50 meters???....I think you have bigger problems than ammo.....

low or high, i haven´t done a sight in. So you could claim that the underbarrel is 25cm high and the topbarrel 25cm low.

But yes it might be a problem with the rifle. I even suspect it, just because all of the three are more or less shooting equally bad! the fault is more or less constant. the inconsistency is probably on me. Im standing for testing purpose and not the best shooter but not that bad

//Danielj

 

[sestoppelman]

For testing purposes, standing is the least desirable stance.

 

[AZDAVE]

What is the velocity of the factory loads? Are the rounds hitting on the same vertical line?

Do you reload? since the rounds are crossing and assuming that they are on the same line vertically, I would start about 200 Feet per second slower and see if they are still crossing. then work up or down in velocity to pull together a good workable 4 shot composite group under 3in at 50 then fine tune it to get hopefully a 2-3 in grouping at 100.

 

[Daniel Johansson]

What is the velocity of the factory loads? Are the rounds hitting on the same vertical line?

Do you reload? since the rounds are crossing and assuming that they are on the same line vertically, I would start about 200 Feet per second slower and see if they are still crossing. then work up or down in velocity to pull together a good workable 4 shot composite group under 3in at 50 then fine tune it to get hopefully a 2-3 in grouping at 100.

Sako FPS 2592 MS 790
S&B FPS 2608 Ms 795
Norma FPS 2723 Ms 830

S&B and Norma is from a converter but i suspect you rather read in FPS than MS.

Yes i reload but i would rather not Lacking time and trying to scale down. More time in the woods less time in prep. But i have the possiblility to do so if i can´t find another solution.

The problem is to find a slower bullet or a bullet with a totally diffrent speed. Any ideas what make does a slow 7x65R

//Danielj

 

[AZDAVE]

Daniel,

I have been giving this a fair amount of thought and have been going down a couple idea threads.

1. That the bullet used for regulation in 1978 might have been a round nose bullet shape that has a much longer bearing surface than a spitzer shaped bullet. IE in all my doubles that I have worked up a load for there is about a 100-125 fps difference in the Hornaday round nosed DGX/DGS or woodleighs VS the Swift Aframes of the same weight. (Aframes being faster) Both the round nose and spitzer shoot well.

2. Over the years your double had some kind of mechanical problem that took it our of regulation, this would require the re-regulation of the double by Hyme or a VERY good double rifle gunsmith.

You might also want to reach out to @HWL, I believe that he has a Hyem O/U 7x65 and he might be able to give you some better advise.

Thank you for converting from Meters to FPS, that was very thoughtful of you. I am well versed in both systems of measurements being a retired engineer, but still wanted to acknowledge your thoughtfulness.

Dave

 

[Woodcarver]

Sako FPS 2592 MS 790
S&B FPS 2608 Ms 795
Norma FPS 2723 Ms 830

S&B and Norma is from a converter but i suspect you rather read in FPS than MS.

Yes i reload but i would rather not Lacking time and trying to scale down. More time in the woods less time in prep. But i have the possiblility to do so if i can´t find another solution.

The problem is to find a slower bullet or a bullet with a totally diffrent speed. Any ideas what make does a slow 7x65R

//Danielj

Prvi 173gr SP averages just under 2500fps. Published velocity of 2493fps is very close to what I chronographed.

 

[Tommen]

Hi Daniel, I have the same caliber in SBS. I found a good bullet and started to test shoot different loadings. When I was happy with the shooting for the separate barrel. I sent it with the ammo to a gunsmith in Sweden and he regulated it with my ammo. Now it's less than 5 cm on 4 shots on 80m. I know it's in the middle of hunting season in Nordic countries now, so you don't have time to test now.

 

[Daniel Johansson]

Daniel,

I have been giving this a fair amount of thought and have been going down a couple idea threads.

1. That the bullet used for regulation in 1978 might have been a round nose bullet shape that has a much longer bearing surface than a spitzer shaped bullet. IE in all my doubles that I have worked up a load for there is about a 100-125 fps difference in the Hornaday round nosed DGX/DGS or woodleighs VS the Swift Aframes of the same weight. (Aframes being faster) Both the round nose and spitzer shoot well.

2. Over the years your double had some kind of mechanical problem that took it our of regulation, this would require the re-regulation of the double by Hyme or a VERY good double rifle gunsmith.

You might also want to reach out to @HWL, I believe that he has a Hyem O/U 7x65 and he might be able to give you some better advise.

Thank you for converting from Meters to FPS, that was very thoughtful of you. I am well versed in both systems of measurements being a retired engineer, but still wanted to acknowledge your thoughtfulness.

Dave

Great insight with the round nosed bullet! I haven´t thought about the bullet shape that much, need to check the three bullets i have.

Ps. if i want the input from friendly ppl. It´s the least i can do to convert it measure all ppl on the board feels confortably with!

//Daniel

 

[Daniel Johansson]

Hi Daniel, I have the same caliber in SBS. I found a good bullet and started to test shoot different loadings. When I was happy with the shooting for the separate barrel. I sent it with the ammo to a gunsmith in Sweden and he regulated it with my ammo. Now it's less than 5 cm on 4 shots on 80m. I know it's in the middle of hunting season in Nordic countries now, so you don't have time to test now.

Yes, now is not the time for gunwork . (I have two rifle´s in use so im not in any hurry, a 6,5x55 and a 375H&H)

Im quite lucky having atleast three gunssmith with regulationskills in less the 30 mils (200miles) distance.

My problem with reregulate is the choice of bullet. it are talks about the same rules as you guys in Finland. If that will be the case i can use a lightweight copper bullet. Otherwise i would probably go with the S&B 173gn.

//Daniel