6.5 CM short barrel - bullet weight (bc) vs speed

[Iamnotagolem]

I just picked up a Tikka T3X Lite Compact (20" barrel) in 6.5 CM for my 12 year old. Since reloading components are fewer and further between these days, I thought I'd ask the question here instead of throwing time/money at it first.

Does anyone have experience comparing the wind bucking abilities of a faster 130gr bullet, like the 130gr ELD-M compared to the higher BC, but slower, 140gr ELD-M? Or a 129gr ABLR vs 142gr ABLR? If I had all of the components at hand, I could load all options and plug them into a ballistic calculator and the answer would be staring me in the face.

I know there are a lot of unknows, like the velocity node of each bullet to give me optimal accuracy in specific rifle, but I was hoping to get some generalities based on past experiences you guys have had. Maybe the biggest key piece of information is that shots will be limited to 600 yards due to reasonable access to a range with those kinds of practice distances.

Any help would be greatly appreciated!

 

[Deleted member 115360]

At 600y with a 20" barrel, any bullet weight you mentioned will do anything you want it to. I have done these calculations for my 18" barrel sig cross, and I'm supersonic at 600y with basically any weight bigger than maybe 95gr with factory ammo. That extra 2" will give you maybe another 75-100fps than I have. For a 12 year old, I'd load some stuff into the 120's to mitigate recoil and point that young person at the target.

 

[Buck3]

I have a 20" proof 6.5cm that I hunt with. It's outstanding as far as I'm concerned. I am running the node that gives me 2670fps with 143ELDx. It wasn't the best accuracy node, but it shoots well enough. I'm sure you will be fine. I think I stay above 1,000ft/lbs until around 680yds.

Edit, I just read your post again.

I ran some numbers and the 130gr was very close to the same trajectory. As if I was going to miss with 1 of then I wouldn't hit with the other.

 

[Iamnotagolem]

Thanks for the input guys. I have some 120's and 140's that I was going to use for barrel break-in. Those two should give me enough data to interpolate what the 130's would do and I can go from there. Sounds like at my ranges, any will be fine. For hunting, I'm sure velocities will remain within their operational window inside those ranges, and if not, I'll drop down a bullet weight to keep velocities up.

 

[Kimber7man]

For hunting I'd go with that 129 ABLR.

 

[tonechaser88]

I've always thought the hornady 123 gr SST had a pretty nice BC for its class . Similar construction to an accubond if I'm not mistaken? I shot them out of my .260 for a while and they were very accurate.

 

[Iamnotagolem]

Just to follow up a bit if anyone ever does a search for something like this, I loaded up some 140gr Barnes Match Burners with 40gr of RL17. These averaged 2,480 fps out of my 20" Tikka barrel, which previously had 0 rounds through it. I also fired 4 rounds of 120gr Nosler Ballistic Tip factory box ammo. They averaged 2,808 fps using my Magnetospeed Sporter, compared to the 2,900 fps printed on the box out of their longer test barrel. Interpolating the data would put me at about 2,660 fps for the 129gr Accubond Long Range, which keeps it within its optimal operating velocities further than I'll be shooting. It also makes the 129gr ABLR better in the wind than either of these two loads, as well as ever so slightly better than the 142gr ABLR.

I'll retest the exact same loads after about 100 rounds in hopes that the barrel speeds up a bit. Thanks again for your input guys!

 

[Macht]

For 600 and under, I think the 130gr class offers the best balance of velocity and BC. For a younger shooter you might even look at something like the Hornady 120 CX or 123 SST.

 

[StanleyActual]

I built my daughter a 6.5CM on a 16.5" 6.5CM. She's supersonic past 1k with factory 140gn ELDM's with a MV of 2562 @ 1000' DA.