800 yards + calibres: 7.62x51, 6.5x55SWe or 7.92x57 ?

[meles meles]

oomans, we've been pondering. A fair few of you shoot out beyond 800 yards (m) with 7.62x51 and there is plenty of discussion on these fora about the best bullets, powder loads and so forth for that calibre. However, it seems to us that at 800 yards or more the Swedish 6.5x55 cartridge starts to look quite promising, holding on to its energy and supersonic velocity out to 1000 yards or more. Similarly, the heftier (194 gn?) 7.92x57 round looks to have potential too.

Anybody here tried them and can give a comparison against the ubiquitous 7.62 NATO ?

[ovenpaa]

The 6,5x55 should have the legs on the 7,62x51 plus you have the advantage of the high BC bullets to load with. Downside is the lighter bullets will get pushed around a bit more in higher winds however you should still get away with.

As an example my AI with 155 Scenars needs around 2,5Mils (8.7MOA) for a 10mph wind at 1000 yards. The 6,5-284 with 139 Scenars needs 6.0MOA in identical conditions. A modern 6,5x55 will not be so far behind the ballistics of the 6,5-284

[GazMorris]

The 6,5x55 should have the legs on the 7,62x51 plus you have the advantage of the high BC bullets to load with. Downside is the lighter bullets will get pushed around a bit more in higher winds however you should still get away with.

Agree with the assessment of the round, the 6.5x55 will outperform a 7.62x51 in a modern rifle proofed to modern pressures; however the comment about higher wind drift isn't correct. It's the BC which will determine the wind drift and not its mass, so the 6.5 will win out even when using lighter bullets. (Unless I've misread what Ovenpaa is trying to say here.)

For example, a 30 cal 190 grain Sierra of BC 0.53 with an MV of 2750fps will drift about 87 inches at 1000 yards in a 10mph crosswind from 3 o'clock, whereas a 6.5mm 142 grain Sierra of BC 0.59 with an identical MV will drift only 75 inches, about a foot less.

UPDATE - I do think I may be misunderstanding what Ovenpaa's trying to say, as the numbers he quotes at the bottom seem to agree with his choice of calibre but contradict the comment about lighter bullets...

Gaz

[ovenpaa]

Gaz, I did not make a very good job of making my point..

[GazMorris]

Gaz, I did not make a very good job of making my point..

Hehe, couple of post-dinner glasses of wine eh?

Gaz

[ovenpaa]

Erm... A rather fine single malt actually, purely medicinal of course as I am sniffing and coughing.

[meles meles]

Hmmm, the 6.5x55 Swe definitely seems to remain in contention. Any thoughts on the humble 7.92x57 ?

[Sandgroper]

Hmmm, the 6.5x55 Swe definitely seems to remain in contention. Any thoughts on the humble 7.92x57 ?

Does it matter? Everyone will have their own views - good and bad. Just pick one and go for it.

My preference would a calibre I haven't had or used before just for something different and to expand my knowledge.

[dromia]

As the diameter goes up for the same weight bullet/boolit then the boolits BC gets worse. You can shoot heavier boolits to get the BC back but then recoil and pressure goes up.

What do you want to achieve group wise at 800 yards plus?

The accuracy mob seem to go for 6-7mm calibres as the compromise 'tween bullet weight, BC, recoil, velocity, pressure and stuff.

Another consideration if you to get a highly accurate, tight toleranced rifle is the availability of quality components especially bullets and brass in the calibre of your choice to make the best of a quality rifle, action and fitting.

Of course with cast boolits then boolit choice and design is almost unlimited.

[meles meles]

Hmmm, we can see 6.5x55 getting the upper paw, and Dromia seems determined to make a lead founder of us !