Best Velocity for Precision?

[Josh Smith]

Hi Folks,

I'm wondering if there's a general rule of thumb with regard to accuracy from certain weight (or length) bullets from a certain twist.

For example, if I load a .30 caliber 150 grain round for a 1:10 twist, I might be able to adjust the load to anywhere from 2200fps to 3000fps. But would the highest precision be found in around 2400fps to 2600fps?

How exactly does this work? I'm mostly into milsurps and I don't suppose the militaries of the world pay particular attention to precision except in certain specialized applications.

I do like to experiment, but is there a velocity range in which I should look for the best precision?

I do always start at the starting loads and work up.

Thanks!

Josh

[freonr22]

i know the experts will chime in, I am not, but wouldnt barrel harmonics play a factor too? 1/10 20" barrel from different manufacturers, and different profiles mounted differently etc?
and tag. interesting post

[RugerNo1]

What your rifle likes! There is no real velocity that does better than others (unless you are worried about retaining velocity).

My .308 loves two different loads with 155 bullets. One at about 2600 fps and another at 2950 fps. You will just try to see what you get with your loads.

Velocity is more important if you are trying to reach long range. Otherwise, just find out what your rifle likes and go with it!

[XDRoX]

There's no set formula. Different rifles will like different velocities.

[joelogic]

I believe the two different velocities is because of the harmonic nodes.

And yes, keep velocity supersonic for best LD accuracy.

[17+1]

I have had better accuracy results at or near max loads.

[Pete1979]

RE

Velocity has an effect on the BC so I'm guessing that it would have an effect on accuracy depending on how far away the target is. I can tell you that minimum loads with 155s don't group worth a #### out of my 308. Got a batch of 25 loaded a little hotter I wanted to try the other day but it was way too windy.

[choprzrul]

It's voodoo black magic. You must spend hours at the reloading bench concocting the right potion, then test it extensively at the range. Be forewarned: if you start down this path, you may never return. The dark forces of accuracy and precision shooting might steal your heart.

.....well that, or just reload some to see what your rifle likes.....

.

[CSACANNONEER]

Every barrel is going to be different and every bullet going through a barrel is going to like different velocities better than others. Now, to make it a little more complicated, a certain barrel's pet load will change over the life of the barrel. In other words, NO, there is not hard fast rule.

[GeoffLinder]

Accuracy is best achieved by finding a barrel node. No two barrels will usually share the same characteristics. Each barrel will have a number of nodes. Usually but not always one of those nodes can be identified as providing slightly better results than the rest. Generally speaking the lower velocity nodes are better choices if you want to extend barrel life and the higher velocity nodes are the best choice if you want better LD performance. BC is effected by velocity and the slower something starts at the barrel, the closer it will go sub-sonic downrange and the more it will drift in the wind across it's flight path getting to that point (joelogic was on the money about that).

[uscbigdawg]

Two schools of thought that I trust.

First, is following the barrel's harmonics and then when developing from there. Dan Newberry expresses this well in his Optimum Charge Weight theory.

Alternately, like 17+1, I'm a firm believer that best PREDICTABLE accuracy comes from higher velocities. A very well known shooter, who does VERY well and routinely wins matches at Camp Perry, develops his loads this way:

1 - Starts with a 90% max charge of the caliber of choice
2 - Add 0.5 grains of powder at a time until it's difficult to open the bolt on his rifle
3 - Goes back to the previous load that "worked" and then plays with seating depth

Done.

The latter is a little hairy, but is safe inspite of what many think. However, a lot of his confidence in this method comes from his understanding of the rifles, their manufacture/materials and that he builds his own rifles. In the first method, I use this a lot now and in my 308, it's proven to allow me to take some risks and get good hits because of its predictability.

Rich

[Ahhnother8]

Every barrel is going to be different and every bullet going through a barrel is going to like different velocities better than others. Now, to make it a little more complicated, a certain barrel's pet load will change over the life of the barrel. In other words, NO, there is not hard fast rule.

As above. And max loads tend to be the best for any given rifle. Which may be far beyond the max listed in any reloading manual. Just be smart about it.

[CSACANNONEER]

As above. And max loads tend to be the best for any given rifle. Which may be far beyond the max listed in any reloading manual. Just be smart about it.

I've gotta disagree with you here. At least for 50BMG Amax bullets. I've run with up to 235 grains of H50 under them and found that 215-222 (depending on which gun I use) tends to give me the best preformance. When it comes to Amaxes in 50s, this is common. In fact, I don't know anyone who has good luck with them at near max loads.

[Josh Smith]

Thanks folks.

Here's the deal: I'm actually above max according to Hornady on the 7.62x54R loads. I use 47 grains of Varget. This is Hodgdon starting load, but 0.5grns above max according to Hornady. I did call Hodgdon and they assured me the pressure was safe. That load is pushing around 2700FPS from their test barrel.

The 7.92x57J gets loaded with 46.5 grains of Varget, which, according to Hornady's test barrel works out to something around 2550FPS. Hornady's shows a bit faster. Additionally, Hornady's loads show this as mid-range while Hodgdon shows it as 1grn over starting.

Now, I'm not sure that pushing the 7.62x54R as fast as I am is accomplishing anything. I'd sort of like to start working backwards on that cartridge, but especially on the 7.92x57J load using Hornady's data, as I'm not real comfortable pushing the old Gew88 quite that fast.

I'd like to shoot for around 2500fps in both, bumping velocity up or down a few feet per second to stabilize the bullet as needed.

The longest shot I can foresee ever taking would be 200 meters or so. Certainly no more than that, and probably not that far as there are only a couple places where I could take a shot that far, don't know why I would, and would have trouble seeing much past it with my 20/40 vision which I feel is a bad habit to correct when shooting if one carries a firearm for defense.

I'll be saving powder, brass, and undue wear on the rifles, especially the old German gal. I'm still in pressure specs for Gooey's action, but not by a whole heck of a lot. No reason to stress it.

The Mosinka I don't think could care less about how much stress I put the action under, but because of the primitive gas venting system (it does have one; you can see it if you smoke the action with the bolt closed, but it's certainly not up to, say, Remington 700 standards), I'd rather not push it too high, either.

Looking back on performance, I really sort of like the old .30-40 Krag, which ran around 2500fps. Heck, the .30-30 runs less and gets used plenty!

Does anyone see any practical disadvantages to loading the old working gals down to 2500FPS give or take a few feet per second? I started low and worked up, and now would like to fall back a bit.

Any and all thoughts are welcome.

Thank you!

Josh

[Coyotegunner]

Yea.What they said.My example.My Ar 24" 204 rifle is only kind of accurate with any load pushing a 40 gr bullet.Top load in a 32gr or the lowest load in a 26gr will put the bullet through the same hole at 100yds.Another rifle Rem Sendero 300RUM,keep the velocity up with any 180 or 200gr bullet,same hole at 100yds.It produces 1" groups with lighter loads.And the group grows and produces flyers with 150/165gr bullets.BUT,on the other hand I have a Rem older police 308 that is very accurate with any bullet or charge.I also ran into the Tikka syndrome of getting along only with flatbase bullets in 308 and 7mm-08 regardless of the charge.The 223 ARs I use with 1-9 or 1-7 twist produce wonderful groups using the same loaded 40gr bullets.My bolt action 223s in 1-10 and 1-12 both like the minimum charge with about any good quality bullet.Sorry to go on with my opinion,but I can not bring myself to purchase loaded ammo.Pm me and if I have loaded it and can tell you what I use.