First batch vs bought ammo

[Spencer54]

I'd shot these at 300 previously and they were spot on - no issues at all.
They were back to back with club ammo, it was only at 600 yards they appear to be that much lower.

They werent hitting the mantlet, just bottom of the white, where my club rounds appeared to be high top of the target. I wasn't expecting such a variation as they'd performed almost identically at 300.

Hope that makes sense?

[Spencer54]

Seems the bought ammo was actually 147gr and similar to GGG spec not 168gr.
That will teach me to pay more attention.

Now everything makes sense, higher velocity and lighter bullet = less drop.
Laws of physics strike again...

Thanks everyone.

[kennyc]

I'd shot these at 300 previously and they were spot on - no issues at all.
They were back to back with club ammo, it was only at 600 yards they appear to be that much lower.

They werent hitting the mantlet, just bottom of the white, where my club rounds appeared to be high top of the target. I wasn't expecting such a variation as they'd performed almost identically at 300.

Hope that makes sense?

if your round is underpowered it will start off slow, it won't get any faster and air resistance and gravity will take its toll, the drop at 600 is way more than the drop at 300 the rate of drop is not linear its more of a spiral ie a tightening downwards curve, the further it goes the slower and thus the more it drops, personally I would look at the book loads and start somewhere below max -10% and work up from there, but do your research try the manufacturers site I linked to earlier, cross check it with any other sources you can find, load to the stated length for the bullet you are using, you can get an idea of bullet speed by comparing the difference in drop between the 300 and 600 targets, but a Chrono helps as well .

[Spencer54]

Seems the book (Nosler) recommended 40.5gr is a full 3gr lower than the website.
Being new and following the start low principle that's what I chose.

So testing at up to 300 shows no real difference.

My question now is:

Going forward from here how do I test my loads for ranges up to and beyond 600 safely?
Zero range and even 300 it didn't show up.

Do I need a chrono?

For a beginner this is a bit daunting, quite a lot of warnings about being over but nothing much on being under by a small amount.

These were supposed to be plinking rounds, but did so well I thought they'd bebfine

[jmc67]

Ideally you need a chronograph. I have one of the Magnetospeed V3 and they are excellent. If you don't want to buy one yourself, then perhaps a club one which can be shared out as needed could be a way to go about it.

The QuickLoad software is also very good.

[kennyc]

Seems the book (Nosler) recommended 40.5gr is a full 3gr lower than the website.
Being new and following the start low principle that's what I chose.

So testing at up to 300 shows no real difference.

My question now is:

Going forward from here how do I test my loads for ranges up to and beyond 600 safely?
Zero range and even 300 it didn't show up.

Do I need a chrono?

For a beginner this is a bit daunting, quite a lot of warnings about being over but nothing much on being under by a small amount.

These were supposed to be plinking rounds, but did so well I thought they'd bebfine

if you have a smartphone then an app like strelock will be able to give you estimated drops at various ranges, a webpage such as JBM can give you a guidline to speeds and drops then you need to get out on the range, I tend to zero at 100 then move onto a longer range, ideally 300 adjust for your expected drop and fire a shot, make a note of your adjustments then compare how much you had to adjust to how much the app says you need, from that you can get an idea of how close the app is to reality . you can adjust the bullet speed in the app until the drops match and then you have an idea of actual speed, coarse but for plinking more than adequate.
a chrono will definitley help as you move closer to max loads and will also show the deviation of speed from shot to shot, but you don't need one straight away, and can probaly borrow one, does your club have a club chrono?
keep a note of your drop adjustments and you will be able to get on the target out to 600 fine, for longer then you need really to have an idea of speed as bullet drop is going to be a massive problem if you don't have sufficient velocity to start with.
it really isn't as difficult as some folk like to make it (unless you are competing at F or FTR) you are starting in the right way =low and working up but for longer ranges you will need to be in the upper end of the powder charge range, just increase in small amounts, say .2-.5 of a grn and take your time.

[WelshShooter]

Based on what others had said, you should have a good idea on elevation adjustment to get to 600 before you start. So how do you do that? You should start by measuring the muzzle velocity of your ammunition using a chronograph and zero the rifle at a known distance (100 yards is typical). The type of chronograph should not matter. You can then use a ballistic calculator to determine the bullet drop over set distances. You will need to know:
+ Ballistic coefficient of your projectile, which should be available on the projectile manufacturers website (it usually gives G1 or G7 drag factors).
+ Muzzle velocity
+ Bullet mass
+ Zero distance

I can recommend the Hornady ballistics calculator. I used this with Lapua bullets before I started using the dedicated Lapua android app, and it was good enough to get me on Fig11 at 1,000 yards give or take a few yards. There's a "basic" calculator or an "advanced calculator", of which the latter asks for some environmental details and shooting angle etc. It might be useful to run both scenarios, using details of your local range such as altitude and what not. These will have a noticeable effect on your trajectory.

http://www.hornady.com/ballistics-resou ... calculator

However, real world data is much more useful! Try using the ballistics calculator at 300 yards to see how far off it is. If it's accurate and you're comfortable, try using it at 600 yards or an intermediate distance if your range has the facility.

[Spencer54]

I don't have access to an chronograph- but I might be able to use one on the next shoot if I can sweet talk someone. I'll post the results either way as it's a good lesson for people following on behind me.

Just to confirm for any newbies that read the post - the books as they are and no matter how new need a cross reference with the manufacturers website. Are they by default so "safe" that the loads are significantly under charged you'll be low on the paper.

That's my lesson!

Thanks guys appreciate the time taken to reply.

[Daryll]

Another factor (that has caught me out) is barrel length... much of the load data is done with 24 inch or longer barrels. if your barrel is shorter, you lose velocity.

Approx 25fps per inch..

So if you're shooting a 20 inch barrel, you're losing 100fps over the published velocity, which then throws out any ballistic calculations.