load data info?

[DMC99999]

Hi all; I have a 20 inch Grendel barrel, and I have mounted a Primary Arms 4x14 x44 ffp scope on it. P.A says that for the scopes reticle to work correctly i need to get a 123gn bullet moving at 2650 fps. any Ideas where to start. I have looked around the net a bit but, have only found loads that will get me up to 2550fps. Any info would be much appreciated. Thanks

[depletedyourcranium]

Don't go off manufacturers recommendations for BDC, it's never going to be precise. Download a ballistic calculator like Strelok, punch in your data and figure out your holdovers for whatever load you want. It's a much better way than trying to "square peg" a load into a "round hole" of a reticle.

[A5BLASTER]

If you get a 123 bullet going that fast out a 20 inch your going to break something very quickly. I.E to get that speed your going to be in very high pressure ranges. Way above sammi pressure spec.

I wouldn't worrie about trying to match the ballistic layout of the scope. Worked up a great load at a safe pressure limit for your rifle and chonagraph it.

Keep very detailed info in a ballistics app and get a range finder, that will be more accurate then any kind of speed based reticle.

[grayfox]

I am actually moving gradually away from my bdc style reticles to straight moa-based. You might want to consider that. With the strelok app it's turning out to be better than using bdc's with some kind of off the shelf markings, be they circles, 1.5/4.5/7/11 or 200, 300, 400 etc drops, etc etc. Shooting different bullets and powders means too many variables for bdc to cover, plus you can't dial for that distance your target actually ranges for.

[bravo5two]

Hi all; I have a 20 inch Grendel barrel, and I have mounted a Primary Arms 4x14 x44 ffp scope on it. P.A says that for the scopes reticle to work correctly i need to get a 123gn bullet moving at 2650 fps. any Ideas where to start. I have looked around the net a bit but, have only found loads that will get me up to 2550fps. Any info would be much appreciated. Thanks

2650 fps? Not for 123 gr, more than likely no way to get there without breaking something. Not worth it.
The hottest load from Hodgdon reloading data for 123 pills only shown 2500 with 24" barrel. Similarly, Sierra 123 HPBT shown the same max load @ 2500 fps. Best is to work up load from below max, test it with your barrel over a chronograph. Don't rely on published data for velocity out of your barrel. In particularly when trying to use the bdc reticle from any scopes.

A little bit off topic - If you insist on using the PA scope's reticle substensions, do the math assuming a MV of 2580 out of their test barrel of 24", subtract 100 fps estimated loss for the shorter barrel, run a ballistic calculator using this velocity to find ballistic data. Acquire substension data from PA for your scope and try to match that to your calculated data with different zero distances. Most likely 200 yds zero would work instead of 100.

[LR1955]

Hi all; I have a 20 inch Grendel barrel, and I have mounted a Primary Arms 4x14 x44 ffp scope on it. P.A says that for the scopes reticle to work correctly i need to get a 123gn bullet moving at 2650 fps. any Ideas where to start. I have looked around the net a bit but, have only found loads that will get me up to 2550fps. Any info would be much appreciated. Thanks

DM:

What will you be using this for? Target sizes, max and minimum distances, how fast you need to engage, and if the target is moving or stationary ought to give enough info for a fix. May be you just have to zero the thing at 500 yards and accept give above and below that distance. One thing you probably won't do without shearing bolt lugs and or damaging your rifle is get 2650 fps from a 123 grain bullet out of a AR-15 Grendel.

LR55