How to correct drop?

[Antares]

Get a good zero
Plug in estimated velocity and bc from mfg
Shoot at 600 and adjust velocity to match your drop
Go to 1000 and adjust bc to fine tune drops at distance

You don’t need a chrono, spend the money on powder and primers.

Exactly this. I've never owned a chrono.

I'm even lazier...

- 10-shot zero
- Plug in estimated velocity and bc from mfg
- Shoot at 500 and adjust velocity to match your drop

Go shoot. That's it for me.

 

[wind gypsy]

Edit: Applied ballistics says 0.209 G7 for a 124 Hammer hunter, use that. Do tall target scope test to verify scope tracks true. Then true velocity by actual drops. At under 600 yards it will be mostly velocity but inflated BC can have some impact.

JBM says at standard atmospherics and 10mph 90 degree wind and 3000 fps MV, the gap between AB measured BC and Hammer advertised with that bullet is 4.5" in elevation and 5.7" of windage. 0.2 mil and 0.3 mil respectively.

 

[mxgsfmdpx]

Get your hands on a chronograph and make it easy

Even with a good chrono like the Garmin, OP is still very likely going to need to true the velocity and/or update charts/app to make confirmed hits line up properly.

 

[mxgsfmdpx]

Exactly this. I've never owned a chrono.

I'm even lazier...

- 10-shot zero
- Plug in estimated velocity and bc from mfg
- Shoot at 500 and adjust velocity to match your drop

Go shoot. That's it for me.

This really does work very well OP. Since you don’t have access to a chrono and aren’t sure about BC, this is your route.

@Formidilosus has a thread somewhere on here that explains this step by step I’ll dig it up.

 

[mxgsfmdpx]

This should be a stickied thread always at the top in long range forum in my opinion.

Read it all but look closely at posts 4 and 5.

How to use a mil/mil scope-reticle, turrets and proper usage

I have gotten a bunch of requests to write up a "how to" for using mil reticle scoots. In this case the SWFA Milquad reticle. It is the 6x42mm SS with MQ reticle in the pictures, however the process and use is the same as long as you have a scope who's reticle matches the turret adjustments-...

rokslide.com

 

[Lawnboi]

Even with a good chrono like the Garmin, OP is still very likely going to need to true the velocity and/or update charts/app to make confirmed hits line up properly.

With a hammer, probably. With any other well known bullet, at 500 yards, he really shouldn’t.

 

[wind gypsy]

AB has hammer BCs. @SouthPaw Confirmed tested BCs that align with what AB has. Use that, true the velocity. Unless hammer has wild swings lot to lot i don't see why that wouldn't work well like it does for everything else.

Good data in (including density altitude), adjust velocity until firing solutions match.

 

[EdP]

A completely acceptable chrono will cost you $160 (ProChrono DLX). Why continue to guess and burn components and barrel life?

 

[mtnbound]

With a hammer, probably. With any other well known bullet, at 500 yards, he really shouldn’t.

Validating what the computer is telling you is always a good thing to do IMO.

 

[Antares]

A completely acceptable chrono will cost you $160 (ProChrono DLX). Why continue to guess and burn components and barrel life?

Why use a chrono if you're going to disregard the results and use a different value after truing?

 

[mxgsfmdpx]

Use a chrono or don't, it doesn't matter. OP doesn't own one, so suggesting he buy one when it is not needed isn't ideal as @Antares mentioned.

I personally still use a chrono for only one reason now, used to be two reasons...

1. I used to re-load most of my ammo and it was a useful tool for that application going back 25+ years of shooting both causally and professionally.

I also used to do a TON of ballistics gel and ply wood stacking shooting with reduced hand loads, which simulated long distance impact velocities with ballistic tip and "match" style bullets. Bullets that hunters and guys I shot with said "I can't use on animals". This allowed me to keep the chrono at my barrel and shoot into gel at 20-50 yards and closely simulate impacts at 500-1200 yards (not apples to apples but it was great info which ended up translating well in animals at range).

2. The only reason I use it now is I am a bit of a data nerd and shoot only factory ammo; and a whole heck of a lot of it. I like to occasionally keep track of factory ammo ES/SD and see what happens lot to lot. As mentioned by @Lawnboi out to 500 yards you have guys are killing (or wounding and tracking due to no follow up shot skill) using box velocity with a 20" barrel. Scary to think about, but he's correct in that you will likely still get vital sized hits shooting prone or on a bench in an IDEAL shot position.

 

[EdP]

Why use a chrono if you're going to disregard the results and use a different value after truing?

That's a valid point if the actual BC is significantly different from published. I have not had that issue.
My chrono is used during load development so I can compare stats to group size. Once I've settled on a load I know the MV. Using a ballistic calculator little or no correction has been necessary to extrapolate out to 500 or 600 yds and proof the load at those distances. For me those are max hunting distances and if any minor correction is needed I do it with holdover adjustments. Perhaps there are better ways but this has worked for me. Obviously if the results predicted by the ballistic calculator were far off at the distances being shot this wouldn't work very well. Having the published BC being accurate for the chosen bullet is essential.

 

[Antares]

For me those are max hunting distances and if any minor correction is needed I do it with holdover adjustments. Perhaps there are better ways but this has worked for me.

Can you help me understand this? You're dialing for 600, then fudging it up or down with a reticle hold... or your using a reticle holdover at 600, then fudging that up or down...? Why not just true your data?

Having the published BC being accurate for the chosen bullet is essential.

Essential for what? Using my 6.5CM profile, I have to change my BC by >15% to get a 1 MOA change at 600 yards, and I could compensate for most of that by adjusting velocity.

That's a valid point if the actual BC is significantly different from published.

So the method I laid out only works if you have the wrong BC but not if you have the correct BC?


This is directed at the general reader, not you specifically @EdP. Be cautious of fooling yourself into thinking you know more than you do, or can control more that you can. Under the best of circumstances, BC and MV are still just estimates; accept that and move on. Putting together drop data that gets you within +/- 1 MOA out to 600 yards is not difficult, don't make it harder than it needs to be.

 

[koppertop]

This should be a stickied thread always at the top in long range forum in my opinion.

Read it all but look closely at posts 4 and 5.

How to use a mil/mil scope-reticle, turrets and proper usage

I have gotten a bunch of requests to write up a "how to" for using mil reticle scoots. In this case the SWFA Milquad reticle. It is the 6x42mm SS with MQ reticle in the pictures, however the process and use is the same as long as you have a scope who's reticle matches the turret adjustments-...

rokslide.com

Thanks for linking that thread. It’s roughly what I was trying to do but I had two unknowns BC and velocity where I’m pretty sure Form only guessed on MV but had a solid BC. That thread is GOLD!

 

[koppertop]

AB has hammer BCs. @SouthPaw Confirmed tested BCs that align with what AB has. Use that, true the velocity. Unless hammer has wild swings lot to lot i don't see why that wouldn't work well like it does for everything else.

Good data in (including density altitude), adjust velocity until firing solutions match.

Wow thanks for tracking down hummer bc’s in AB! The fact that they jive closely with SouthPaw’s is great!

 

[koppertop]

Edit: Applied ballistics says 0.209 G7 for a 124 Hammer hunter, use that. Do tall target scope test to verify scope tracks true. Then true velocity by actual drops. At under 600 yards it will be mostly velocity but inflated BC can have some impact.

JBM says at standard atmospherics and 10mph 90 degree wind and 3000 fps MV, the gap between AB measured BC and Hammer advertised with that bullet is 4.5" in elevation and 5.7" of windage. 0.2 mil and 0.3 mil respectively.

When you say the gap using the two different BC’s is 4.5” elevation, at what distance is that? If that is at 580 yards I might have been in the ballpark for using the incorrect bc.

 

[wind gypsy]

When you say the gap using the two different BC’s is 4.5” elevation, at what distance is that? If that is at 580 yards I might have been in the ballpark for using the incorrect bc.

Sorry, I think that was 600 yd.

 

[SloppyJ]

I use my garmin chrono to get a solid baseline to get me started. While I'm zeroing the rifle I'm gathering velocity data. From there I plug it into my profile and see what it spits out.

I typically shoot at 300yds first and I very rarely have issues there. Next is 600yds and I'll tune my velocity to get me on track.

After that I jump straight to 1000yds and tune my BC. My last batch of dtacs I ended up with a .328 G7 and 2895fps for a load that my chrono said was 2870fps. After that I verify at 400 and 500 and then shoot. BC seemed really high but it was working.

I ended up shooting 14th out of 32 shooters so I don't think that was too bad for my second match.

I can and will tweak it a bit more to really dial it in. I only had about 30min to do this before the match and it was a new load. I'm sure it can get better. This has worked for me.

 

[EdP]

Can you help me understand this? You're dialing for 600, then fudging it up or down with a reticle hold... or your using a reticle holdover at 600, then fudging that up or down...? Why not just true your data?

I don't dial in most cases. I holdover using BDC reticles. Have not needed to true my data from the calculator predicted values.

Essential for what? Using my 6.5CM profile, I have to change my BC by >15% to get a 1 MOA change at 600 yards, and I could compensate for most of that by adjusting velocity.

Essential for getting a valid and useable result from a calculator w/o having to true the data.

So the method I laid out only works if you have the wrong BC but not if you have the correct BC?

You questioned the need for a chrono and asked why not just true the data. With the MV from my chrono the ballistic calculator has given me accurate results. No need to true data in that case. If I saw results that indicated BCs off by 15% as you have, I'd be truing the data too, but I think I'd also be ahead by having the MV. Otherwise, how do you know if it is the MV you have assigned or the published BC that is off?

 

[Lawnboi]

The issue with trueing is that environmental are now a factor. Like a longer range zero, your assuming everything is static out there. I understand it sometimes needs to be done and I have done it in the past. Normally I’ll only trust it for the day/ area I’m in. I’m also only speaking to supersonic trueing.

Trueing to certain environmentals has bit me before, partially by just not knowing what I’m looking at(environment), partially because that’s what the internet told me to do.

On top of environmental you could now be truing, any zero error, which a lot of guys have, into your solver. Now down the road when you adjust your zero 2 tenths, everything down range that you trued may not be where it should.

An example would be I can go to a range, on 5 different days throughout the year and need to adjust small amounts. Knowing when and why is the hard part and truing is not a one size fits all the internet plays it to be.

On top of that, almost nobody is trueing with statistically relevant group sizes.

I’ll say it again, using known bullets or known BC, if your truing anything at supersonic ranges, you need to take a hard look at your rifle system and environmental factors.

Since I stopped velocity truing and focusing on the above, I have had zero elevation errors out to supersonic ranges. None. As in I go for a 4 hour ride and am hitting small targets because I trust the BC, know my scope works, have a balls on zero, and have accurate velocity.

Now that Garmin changed the game it’s even easier. If I notice anything strange happening I can slap that thing on my gun for a few shots and eliminate that as a variable. I’ll shoot a few over the chronograph any time I’m confirming zero. It’s simple and makes everything else simple.

Nothing is more frustrating than chasing elevation problems.

If you prefer the guess, check and confirm method that can work too. I do the same thing but instead of burning rounds getting a trued velocity I take 5 shots at small targets on a day where environmental are within my ability to read.