Gents,

Thoughts please. I managed to get a good load on RWS 7x65R with the HIT Bullet on a clearout sale. Paid less than the cots of the brass. Its a non-toxic bullet loaded to 890 m/s.

Now I have always known that combinations shoot high when the barrel is warm, and with my homeload trundling along a 2,600 fps, 2nd shot was c3" high. But I completely missed a Roe doe the other day. Shot the youngster, and then reloaded and held a little low and went straight over the top. Tried it on the target yesterday, and from a warm - not hot - barrel it was 6 to 8" high. But cold barrel - all shots touching.

Sounds about right. My second shot goes about 1-1/2" low at 100 yards and a bit right, my third goes about 6" low and a bit further right. Don't even waste ammo finding out where the fourth one would hit; have to have a bigger target, anyway. That's with the Brno BBF. The Hollenbeck drilling is a little less extreme, but right close. Kentucky windage is the only answer, or patience.
windy

I consider myself lucky that my 12gax7x57R combo guns give 3 shots from the rifle barrel before group enlargement.

Thanks - was just surprised at how far off the HIT ammo is compared to lower velocity homeload. When I expect to need quick follow up shots I have an einstecklauf in 7x65r so in effect a double rifle.

With proper double rifles where both barrels are soldered do you also get big movement when the barrels are warm, or does the heat of both barrels counter each other?

Wow! That is a LOT of movement. From all my drillings I can easily get 3 shots less than 2 inches. The first two will always be around an inch and the 3rd always starts walking. Only thing I can think of is the loads are hotter and the barrel is heating quicker and hotter?

When shooting my ancient double rifles, if I shoot groups going right, left, right, left they hold pretty well.

Which barrel is on top? Savage 24V goes lower as it warms, rifle barrel is on top.

I have not found that to be true with a good double rifle..Wonder why a drilling would be so..Don't have much experience with drillings..

The German term for this is "klettern" or climbing. A solid ribbed drilling should put the first 2 shots within an inch of each other but after that if shooting continues, the group will climb. The top of the rifle barrel is attached to a solid rib which dissipates the heat and limits expansion....whereas the bottom of the barrel will heat and expand. This is the reason that some makers have produced combination guns and drillings without the solid rib or with a synthetic rib between the barrels. This shouldn't matter because the drilling was never intended for volume shooting. That's why you would use a "Repetierer"...a bolt action.

Here are 3 shots from a drilling with a 7x57R at 100 yds...pretty typical...the last shot having "climbed" the highest.