6.5 PRC head scratcher.

[king1886ranch]

I’m loading a 6.5 PRC up for a guy and can’t wrap my head around these numbers. Here’s my load:

140gr Berger Elite Hunter
58.2gr Retumbo
Fed 210m primer
Gunwerks brass

Here’s where it gets interesting. Self admittedly I have not chronographed yet, but I was sure (after extensive reading of load data) that I’d be somewhere around 3075fps with this load so I didn’t bother before taking it out long range. When I trued my dope it “trued” MV at 2740fps.

I’m planning on loading some more up and testing with the magneto tomorrow but I just don’t get it. Am I missing something? I know the dope is correct, I confirmed hits at 850, 1146, 1400 and had 3 hits in a row at 1877 yards.

 

[BigTex]

What barrel length? What BC are you using? What ballistic software?

For Reference I have a 26" 6.5x284 and it does 3080fps with 140gr Berger VLD and 57.1gr H1000, so your 3075 estimate shouldn't be far off.

 

[king1886ranch]

@Travclem 22” barrel 1:8 twist and I’m using Applied Ballistics with Litz’s custom drag model.

22” might be a little short for that much powder but I would think it wouldn’t account for 300fps. Only thing I could of last night was that maybe the scope doesn’t track correctly. If that’s the case then could calibrating ballistics account for that? I tried at 850 then went out to 1400 and tried again. Got them on then checked it at 1146, dead on, then checked it at 1877 again dead on.

 

[BigTex]

Maybe try to use a g7 BC instead of a CDM. The CDMs have caused a few people problems in the past.

 

[king1886ranch]

I’ll try that