Sighting in a small bore double?

[rookhawk]

Hello friends, sanity check me on best approach for my young son’s double rifle.

we picked up a 7x65r heym on this forum and just swapped the scope out to a 1-6x appropriate for the gun. It’s a single trigger, over/under so I’m trying to figure out what approach I should take for sighting in the gun.

options:

1.) do two sets of two composite groups. Take the average. Zero the scope at this average center at 50 yards, or 1” high at 50 yards.

2.) Sight it in for perfect regulation using only the first shot aligned to the optic, ignoring the 2nd barrel.

For a side by side, a double trigger, or a large bore I’d be inclined to take option 1 above. But thinking that the gun may be used for plains game, boar, deer, or elk, maybe the first shot should be dead-on and the second barrel is thought of as +/- 3” insurance, thus option 2?

 

[mark-hunter]

I vote for option 1. Of course, before that find ammo that groups the best.

 

[rookhawk]

I vote for option 1. Of course, before that find ammo that groups the best.

In America there are zero ammo choices. We have two cases of Geco German ammo for the gun and Heym claims that’s what they use to regulate them. If it regulates poorly, the only remaining option is hand loading.

 

[Red Leg]

In America there are zero ammo choices. We have two cases of Geco German ammo for the gun and Heym claims that’s what they use to regulate them. If it regulates poorly, the only remaining option is hand loading.

I would sight it in as a single. I should note that I do that on my S2 30-06 and .375 as well, and both sets of barrels shoot two-inch composite groups at 100 meters. With that, I get first shot accuracy to the max effective range of the chambering and a back-up shot within a couple of MOA.

I think that technique is even more important with a less well regulating rifle. Your son needs absolute faith in that first shot. Hopefully, he is getting consistent groups from the first barrel?

 

[HWL]

Clearly option 2.

Make the first shot count.



HWL

 

[HWL]

But after a while, after you have burned a lot of money and ammunition,....you will not satisfied with two different points of impact.

You will look for a solution.

And you will burn another pile of time, money and ammunition by regulating the barrels by reloading.

And it will NOT work, no matter what the reloading gurus may tell you.

Because ammunition is not the cause!

You have to regulate the barrels - by a regulation device.

A good gunsmith can make it, Heym does it ..... and it works forever, whatever a ammunition may come.

I am proud owner of two Heym O/U, one in 7x65R, the other in .30-06 Springfield.

Both are extremely accurate with both barrels, and regulated to the same point of impact.

 

[mark-hunter]

I think that OP did not mention that barrels are not regulated. Just asking for opinion on how to zero.
I think the proper way would be testing and zeroing with various ammo, if it doesnt work to satistaction, then regulating the bbls with reputable gunsmith.

 

[HWL]

I think that OP did not mention that barrels are not regulated. Just asking for opinion on how to zero.
I think the proper way would be testing and zeroing with various ammo, if it doesnt work to satistaction, then regulating the bbls with reputable gunsmith.

May be, ....but why should he have two different groups and zero to an average center...

Why should he "ignore" the point of impact of the "second barrel"?

Double rifles are a fantastic tool, when they shot straight....

HWL

 

[mark-hunter]

@HWL
op did not report problems with regulating, so the idea is that rifle is reasonable well regulated, and in that case sighting in as per average impact from both barrels, I consider as good enough.
The brand is heym, so it is not italian factory DR, i see nothing to raise the red flag in advance.

 

[IvW]

Option 2

 

[rookhawk]

I would sight it in as a single. I should note that I do that on my S2 30-06 and .375 as well, and both sets of barrels shoot two-inch composite groups at 100 meters. With that, I get first shot accuracy to the max effective range of the chambering and a back-up shot within a couple of MOA.

I think that technique is even more important with a less well regulating rifle. Your son needs absolute faith in that first shot. Hopefully, he is getting consistent groups from the first barrel?

We’ll know today or tomorrow. We don’t live near a place to shoot and it is literally a 3 hour, $150, round trip endeavor to go to a shooting range by us that is operated by pain in the ass old guys with no knowledge of guns, that think they are experts, and have nazi rule enforcement policies. (e.g. can’t shoot off sticks, can’t shoot a semi-auto with more than one round in the gun, etc.)

I digress. We’re up in New England on the family farm and we just swapped the 3-9x50 leupold on the gun for a 1-6x24 swaro. Maiden voyage for sighting in the gun in next 48 hours.

Thanks for the opinion, I like your smallbore approach of treating like a single shot with the second shot being a ”spray and pray” to get a second shot into the animal if necessary.

 

[Red Leg]

But after a while, after you have burned a lot of money and ammunition,....you will not satisfied with two different points of impact.

You will look for a solution.

And you will burn another pile of time, money and ammunition by regulating the barrels by reloading.

And it will NOT work, no matter what the reloading gurus may tell you.

Because ammunition is not the cause!

You have to regulate the barrels - by a regulation device.

A good gunsmith can make it, Heym does it ..... and it works forever, whatever a ammunition may come.

I am proud owner of two Heym O/U, one in 7x65R, the other in .30-06 Springfield.

Both are extremely accurate with both barrels, and regulated to the same point of impact.View attachment 411959View attachment 411960View attachment 411961View attachment 411962View attachment 411963

I wish someone in the states offered that service. I have a VC that would benefit tremendously from it.

 

[rookhawk]

But after a while, after you have burned a lot of money and ammunition,....you will not satisfied with two different points of impact.

You will look for a solution.

And you will burn another pile of time, money and ammunition by regulating the barrels by reloading.

And it will NOT work, no matter what the reloading gurus may tell you.

Because ammunition is not the cause!

You have to regulate the barrels - by a regulation device.

A good gunsmith can make it, Heym does it ..... and it works forever, whatever a ammunition may come.

I am proud owner of two Heym O/U, one in 7x65R, the other in .30-06 Springfield.

Both are extremely accurate with both barrels, and regulated to the same point of impact.View attachment 411959View attachment 411960View attachment 411961View attachment 411962View attachment 411963

Very encouraging that your Heym 7x65r double rifles shoot so well. My son’s Heym is a model 26b Luxus bought on this forum. It looks near-new. The Heym catalog says it was regulated for the 173gr Geco softpoint of which we have two full cases, or enough ammo to last my son 30 years of hunting.

We’ll shoot it off sticks and see how it performs. We had not considered the remote possibility that we would be getting the level of regulation that HWL is getting with his Heym. The Heym 26b does not have the adjustable regulating wedge featured on HWL’s rifles and its a fairly inexpensive double so we assumed 2” groups at 50 meters would be to be expected.

We’ll test and find out.

 

[rookhawk]

I wish someone in the states offered that service. I have a VC that would benefit tremendously from it.

I’m not sure if this service is fantasy or possible anywhere? I cannot understand how relaying the regulation wedge and potentially rebrazing the ribs, even with a laser bore guide, is going to create a magical double rifle that can be shot with any ammunition perfectly?

You change bullet weight, velocity, powder burn rate, you’re likely to have a double that doesn’t shoot straight. When I send a double rifle that shoots poorly out for regulation, the first thing the barrel mechanic does is load up something within the specs of 1921 ICI / Kynoch original British load performance and see how it goes. If it goes very well, the mechanic may increase or decrease charge by half a grain looking for exceptional performance. If all that fails, they will relay the wedge or even the ribs in an attempt to get it to regulate with the ICI / Kynoch original load performance. I find it hard to believe if I hired better skilled tradesmen they’d be able to regulate the barrels to work with any ammo perfectly all the time. (I’d need someone to explain how that could be anything but magic or witchcraft as a theory)

 

[Red Leg]

I’m not sure if this service is fantasy or possible anywhere? I cannot understand how relaying the regulation wedge and potentially rebrazing the ribs, even with a laser bore guide, is going to create a magical double rifle that can be shot with any ammunition perfectly?

You change bullet weight, velocity, powder burn rate, you’re likely to have a double that doesn’t shoot straight. When I send a double rifle that shoots poorly out for regulation, the first thing the barrel mechanic does is load up something within the specs of 1921 ICI / Kynoch original British load performance and see how it goes. If it goes very well, the mechanic may increase or decrease charge by half a grain looking for exceptional performance. If all that fails, they will relay the wedge or even the ribs in an attempt to get it to regulate with the ICI / Kynoch original load performance. I find it hard to believe if I hired better skilled tradesmen they’d be able to regulate the barrels to work with any ammo perfectly all the time. (I’d need someone to explain how that could be anything but magic or witchcraft as a theory)

I certainly will agree that adjusting a load can make a tremendous difference in finding the regulation of a particular rifle - particularly if it is unknown. However, powder lots change; bullets come and go; and modern three-inch 50 meter factory regulation looks very different at 100. OU dispersion, for obvious reasons, tends to be vertical rather than side to side. The wedge allows the shooter to adjust that vertical distribution. There was an article on it somewhere a few years ago, and the results were dramatic.

The smaller caliber S2 barrels (SxS) like my 30-06 set are equipped with a similar capability to adjust horizontal dispersion. It works.

 

[AZDAVE]

I hope your range session goes well. I have a VC O/U 8x57jrs and I shot it with irons to start with using normal and S&B and both loads shot to the sights with a composite group just under 2 inches at 50. Then started my search for a scope. I look for the lightest weight scope in the power range. Some doubles have serious issues with weight being added to the top rail. (Had a zoli 8x57 that shot well with irons but the group opened up dramatically with addition of a scope, but shot great with a red dot). I put a 2x7 Nikon on it and crossed my fingers and was VERY lucky. The composite group shrunk to just under a inch at 50, 1 3/8 at 100 and just under 3 1/2 at 200. I have it sighted dead on with the first shot and the second is close enough to reliably hunt with. Also developed a 200fr accubond and 196gr solid loads that shoot a bit better than factory. I hope the double goes bless you with a very accurate double.

 

[Rubberhead]

I just went through this process with a Browning Express under a Leupold 1-5x. I don't know much about barrel regulation but I managed to get a workable solution by shooting two different bullet weights.

My bottom barrel shoots about 1/2" left at 100 yards and my over barrel shoots about 1/2" right a 100 yards. I, kind'a, got lucky on elevation where the two bullets stay less than 1" apart out to 300 yards but the cost is that I have to shoot a heavier bullet in the top barrel which means I have to keep them seperated when loading. With the same bullet weight my barrels diverge with the over barrel about 4" higher than the under barrel at 100 yards.

Here's some random thoughts on your situation in no particular order...

1) To minimize ammo use keep exact records of every shot and every scope adjustment.
2) The under barrel will be .7" to 1.0" below the over barrel and the over barrel will be 1.5" below the line of the scope - you can use a ballastics calculator to run the bullets through the different barrels.
3) With the same bullet weight in each barrel even if the bullets touch on paper at a certain yardage, the under barrel will shoot higher than the over barrel after that - you can use that to your advantage but you have to understand the trajectories and you will need to run your own tables because of the -2.2" for the under barrel at muzzle.
4) If it were me, I'd pick a yardage that would be most typical for my hunting distances then zero the elevation to the barrel that shoots lowest at the distance. If the windage difference aren't terrible - I'd zero the windage for the average of the two barrels.