Hello, I´m looking for a good combination in a CZ550FS of 52cm of barrel an a 8 twist ratio in 6.5x55SE. Until now I´ve been shooting NP140gr at 820m/s with a Carl Gustav but with this one the group are not good. 2MOA at 100m.

I´m thinking in:

-Change bullet, use A-max in 140 with a great BC.

-Change to an lighter bullet like BT 120.

What would be the better bullet and MV in order to have good groups for hunt until 300m in my rifle?

Thanks.

I have found the Sierra 140-grain bullet with 46 to 48 grains of H4831 to be a good load for hunting in the 6.5X55. How much powder you can use depends on the rifle! You must work up your loads from a lower powder charge-for example, 44 grains or so. Increase the chare 0.5-grain at a time, and stop when you find the most accurate combination.

As far as velocity is concerned, the load which gives the best performance in a long barrel will do the same in a shorter one.

Going to a lighter bullet will allow you to get a higher MV, BUT the lighter bullet will slow down quicker. So, at some range the heavier bullet, if of the same shape, will overtake the lighter one.....

What are you hunting? The game you are after will have an bearing on the bullet wgt you might want to use. Deer size game is no problem for 120 gr bullets but if moose or elk sized game is what you are after I`d stay with 140 gr.
The 140 gr Sierra has shot well for me as does the 129 gr Hornady SP (not SST) I use R22 with both and get good velocity, 2700 fps+, along with accurate loads. IMR4831 has also been a good powder for me with 140 gr bullets. I use the 129 gr on deer here and have been real happy with the performance on game. It seems to penitrate similar to the 140s and is a little faster if that matters.
Nosler now has a 130 gr AccuBond that should be a good bullet. It is a plastic tippped bullet with a bonded core and from the reports I`ve read it is also a very accurate one.
The 120 gr bullets have been on the average most accurate for me. Your rifle may not agree with them, but if game is on the deer level is size they are a bullet you should consider. I get excellent accuracy with the 120 Nosler BT. The Sierra is another very accurate bullet. I like H4350 with this wgt but there are many powders that should do.

The most accurate loads for my Swede are the 129 gr Hornady with 37.5 gr's of Varget, the 140 Hornady with 36 gr's of Varget, 5 in .436" at 100 yd's.
I had an SEE effect with 46 gr's of 4831, blew the pimer pocket and I needed a mallet to open the bolt. No gun damage. I switched to Varget.
My friend had the same thing happen to his with the same load of 4831.
The Swede has a long lead to the rifling.

Thanks again.

I´m from Spain, and I can use, basically, three types of powder Tu-3000/5000/7000.

I´m hunting deer size, due to that 120gr also be a good bullet.

But my problem, by now, is the accuracy. With the Gustav with NP140-40.5 of Tu-5000 the accuracy was very good. But wiht this another rifle not. In order to not be always doing changes I´d elected the same wheihgt, 140gr. I now the OCW developement but, knowing the MV and a accu bullet (wheight and type) in short barrels, like mine CZ550FS 52cm, in 6.5x55SE I think that will arrived soon to OCW. And then I would probe the terminal ballistic in deers.

Many thanks, everybody I hope more help. Thanks.