Federal BC's or velocities extremely optimisitic?

[zion zig zag]

You still gotta validate at distance, and preferably at multiple distances. A chrono saves you nothing in terms of zero'ing or validating at distance. I have a Chrono that sits next to my range bag and it rarely leaves my shop.

Any posts here that you know of that talk about step by step validation process? I’ve never done anything besides zero and measure with chronograph and then punch numbers in a ballistic calculator. This works fine out to 400 but I’d like to learn.

 

[SDHNTR]

You still gotta validate at distance, and preferably at multiple distances. A chrono saves you nothing in terms of zero'ing or validating at distance. I have a Chrono that sits next to my range bag and it rarely leaves my shop.


I wouldn’t read too much into that difference. I need to pull out the old data book, but I think one Lot of ELDX was basically on a brand new barrel without a suppressor, and the other was after about 1,000 rounds with a suppressor (IIRC). There’s of course lot-to-lot variances, but the whole 80-fps isn’t solely from lot variance.

Yes, I dont disagree. Of course you still gotta verify your drops, but knowing the numbers will lead to a lot less head scratching.

 

[Wrench]

Be aware that your vertical dispersion will potentially cause errors in velocity estimations.

Don't confuse this with BC errors. You will need to shoot groups and use the groups average to validate.

 

[SDHNTR]

Be aware that your vertical dispersion will potentially cause errors in velocity estimations.

Don't confuse this with BC errors. You will need to shoot groups and use the groups average to validate.

This is an excellent point that is often not considered or blamed on other things. Vertical dispersion can be caused by lots of mechanical and/or form flaws.

 

[Outdoorsman12b]

This is very helpful. Thanks. If I use the lower end of your range (2560FPS) I get very close to my observed drops. So I think it simply is what it is.
A slow load/ barrel.

The method I used is below-
I zeroed with 7 shots at 200 yards.
I then Held dead on target at 300 and 400 and shot 7 shot groups at each.
I then took and average elevation of my groups distance below the target at each range. By doing it This way I know it is not possible for a reticle or dialing error to occur. Since I was holding dead on and measuring drop with a tape on the target

Are you saying you shot a 7 round group at 200 to confirm zero? Or you shot 7 rounds at 200 to zero. Depending on how you zeroed this can be a big issue especially at 200. What group size are you getting?

I use to make the mistake of chasing my zero around after each shot. Now as long as I am on paper I will shoot a group of at least 5 rounds then adjust based on center mass of group. Since that change my zero is where it should be and dialing shots has lead to far less head scratching. Form had a really good post called how to use that new SWFA scope that really breaks down what you are trying to do.

 

[Hunthigh1]

Yeah, there's lots of info out there. I think ideally you are shooting groups at every 100 yard interval on paper & recording real world dope, but that's not always available & might be overkill for a lot of people. A quick and dirty way that I true-up is to zero at 100 yards, guestimate MV, shoot +/- 1 MOA sized plate at 550-yards, make initial MV correction, then shoot +/- 1 MOA sized plate at 1,000 yards. Once I'm comfortable with the hits I'm getting, I confirm data at +/- 330 yards, 420, yards, 650 yards, and 850 yards on small(ish) plates and make sure my ballistic solver is lining up with that real world data. Those yardages aren't special, just how the range is set-up. In general, I'm only modifying MV and running with the doppler derived BC's from AB since I'm using AB as my primary solver.

You can google Weaponized Math, and download a free worksheet from Snipershide. Basically, you get a good zero at 100-yards, you can "try" 1.0 mils at 300 yards to get on paper for almost all centerfire cartridges, then correct to center. From there, the workbook gives you a factor to apply and "try" for each subsequent 100 yard line, which will get you close. Adjust the "try" dope to real world, then apply the next factor.

Also attached is a Firing Solution check list from Applied Ballistics that can be helpful. Tons of other info out there.

This is awesome. Thanks for sharing

 

[Hunthigh1]

Are you saying you shot a 7 round group at 200 to confirm zero? Or you shot 7 rounds at 200 to zero. Depending on how you zeroed this can be a big issue especially at 200. What group size are you getting?

I use to make the mistake of chasing my zero around after each shot. Now as long as I am on paper I will shoot a group of at least 5 rounds then adjust based on center mass of group. Since that change my zero is where it should be and dialing shots has lead to far less head scratching. Form had a really good post called how to use that new SWFA scope that really breaks down what you are trying to do.

I have been shooting groups at each distance then using the average of that group as you suggest. Group size has been about 1.2MOA at 300 and 400 and 0.8MOA at 200 and 100. I will check out that article by form. Thank you.