Load data versus ballistics calculator

[223copperhead]

My load is 23.3 grains RE15 and Hornady 68 grain BTHP
COL 2.255"
Savage model 25, 24" barrel, 1:9 twist, 223 Remington.

According to load data, 22.7 grains RE15 and 68 grain Hornady BTHP
Should be at 2,681 ft/sec.

At 200 yards I have a 5.1 inch drop. According to every ballistics
Calculator my velocity is 2,550 ft/sec.

So here's my questions:

Shouldn't I be shooting faster than the starting load speed?

Are the ballistics calculators accurate enough the base my
Speed on?

Am I missing something's?

PS, I don't have a chronograph yet, so this is not an option.

Thanks for all the advise!!!!

 

[Rule3]

A test is a test. is a test this only a test, with different variables. Your specific set up will be different. Heck the manuals vary all over. A calculator is theory and math in a computer, Algorithms or whatever.

A chronograph will tell what YOUR rifle is doing.


The crash test of my car says I should survive a offset collision but when a semi hits me is that true?

 

[farmerboy78]

I would try it further out, say at least 300 yds then put it in a calculator. But you have to have every input dead on...

 

[HJ857]

Every load I've chronographed needed to be tweaked, or proofed, at the range.

Gravity is a constant value and so is the B/C (assuming it's a correct value). Your variable is MV, so once you get a drop value it's easy to reverse the calculation to arrive at your MV.

I start with a solid 100 yard zero, then shoot to get click values at 300 and then again at 500, then adjust MV until those click values line up. I can do this in fewer shots than needed to get a chrono average and later proofing. If you get an error then the published B/C is probably somewhat off. An app like iSnipe or Strelok makes life a great deal easier.

The chrono is just another tool, it's not the definitive answer, IMO of course.

 

[Schwing]

There are so many variables that play into this that there is no way to know for sure WITHOUT a chronograph.

Many choose not to employ them, however. If you are not truly concerned with the speed and just accuracy, I would just continue working on the load until to achieve the desired accuracy and/or drop and forget about it.

I put little faith in those calculators.

 

[climbnjump]

Gravity is a constant value and so is the B/C (assuming it's a correct value)

Actually, ballistic coefficient isn't a constant. For a given bullet, BC varies with velocity. Sierra Bullets, for instance, publishes several BC values for each bullet. For instance go here: http://www.sierrabullets.com/resources/ballistic-coefficients/ and choose a bullet diameter for some examples.

Most bullet makers list a single BC of course, because most shooters don't know - or need to know - how to deal with BC variation.

So whether or not BC variation actually makes a difference in your shooting depends on your application. For most folks it won't matter. But it is still good to understand the concept.

 

[BigBore45]

is the COAL the same? did you use the same primer at the same elevation as the book test. did the book test use a gun or just a test barrel? to many variables to guess your velocity off the book. and if you are not OCD in setting up every measurement you can think of it is hard to get velocity with bullet drop. wind/ sight height from center of bore to center sight/ ammo temp/ outside temp/ humidity/ gun vised down to not move at all/ target angle/ target height from gun height/ and many more to that equation. Trust everyone on here you want to know your true speed you need a good crony!! good luck

 

[TBJK]

You need a chrony. Really the only way to document items. Document all your shots with all the conditions. Ammo temp, bore condition, case volume, COAL, barametric pressure, wind direction & speed as well as the corrections for that. That's just a few. Get into long range shooting then add more to it.

 

[spitballer]

A chronograph will tell what YOUR rifle is doing...

Have to agree here. Without a chrony I'd be inclined to simply adjust load until I got a fouling shot on the right and then a tight little group left, for right hand twist with thin-jacketed bullets.

 

[Bart B.]

Chronographing Bullets 101

Barreled actions that hard fixed in a mount and don’t recoil produce higher muzzle velocities and lower standard deviations and spreads with a given load than one fitted to a stock then hand held by someone.

The same rifle and ammo can easily have a 50 to 100 fps spread in average muzzle velocity as well as greater spreads in standard deviations when fired by several people holding onto it.

Barrels with smaller bore and groove diameters produce higher muzzle velocities for a given load than those with larger ones. All barrels of a given make and type in a given rifle don’t have the same bore/groove dimensions.

Primers smacked with firing pins with weak springs and/or shallower dents have less flame output producing lower muzzle velocities than those smacked hard and deep with strong firing pin springs.

Powder lots can easily produce 50 fps different average velocities across several of them depending on their exact chemical composition.

Primer lots vary less that powders. And there’s a huge difference in flame output across all primers of the same type with the same firing pin impact conditions. Lower outputs cause lower muzzle velocities.

People get higher muzzle velocities shooting a given rifle and load slung up in prone (conventional or F-Class) than when shooting it from standing without a sling.

Rounds left in a hot barrel for 30 seconds shoot their bullets out faster than rounds fired within a few seconds of chambering.

The first few shots from a clean barrel have bullets leaving 10 to 20 fps slower than those fired after the bore’s fouled.

============================

What’s the difference between your testing conditions and that used to get the load data you’re reading?

 

[HJ857]

Just out of curiosity for the chronograph users, do you get a MV, calculate your drop values and take it for granted from that point on, or do you actually test those numbers at real distances?

 

[climbnjump]

Just out of curiosity for the chronograph users, do you get a MV, calculate your drop values and take it for granted from that point on, or do you actually test those numbers at real distances?

Speaking only for myself of course, I test. Ballistic calculators can get you close if your inputs are good, but because there are variables that they don't/can't take into account testing is important if you really want to know what's going on at longer distances.

 

[Bart B.]

I have chrono'd Sierra 155's and 190's from .308 Win, 190's from .30-.338 Mag, shooting from prone to get zeros at 100 yards with both metallic and scopes. Then used Sierra software to calculate bullet drop at 100. Adjusted the sights to move group centers down equal to sight height above muzzle axis plus bullet drop. I then had what I call a "actual shooting bore sight" for range conditions. I then zeroed the sights windage and elevation knobs and scales.

Most interesting was the first time I did that, I learned the bore axis for zeros didn't point to a place above group center equal to bullet drop plus sight hight. As I remember, it was low and left from that assumed point.

Using Sierra software and having measured each sights exact movement per click, then entering atmospheric conditions for different rifle ranges at altitudes from 580 to 8200 feet, calculated sight elevation settings for 300, 600, 800 and 1000 yards. After checking rifles and loads at all places and distances around the country, first shot with each was within 1/2 MOA of perfect in elevation. Which tells me if you precisely "measure" your stuff and use good ballistic software, you can calculate good longer range zeros from short range ones.

 

[spitballer]

Just out of curiosity for the chronograph users, do you get a MV, calculate your drop values and take it for granted from that point on, or do you actually test those numbers at real distances?

Not sure I understand your question but obviously any numbers will be obtained from the bench. I mainly use the chrony to show me the charge with which the bullet starts to drag on the barrel (obturation) and try to maintain a low enough charge to keep velocity from snowballing. For me this means low numbers, generally around 3000 fps or a little higher with a 30" barrel.

Attached photo (if it attaches)from last December illustrates: these 400 yd, 5-shot targets were done using 55 grain bullets traveling at around 3025 fps. The target on the right already starts to roll laterally from increased velocity from fouling and barrel dilation from heat, and numbers are starting to get up over 3040.

 

[Bart B.]

spitballer, all bullets obturate and drag on the barrel. That's proved by seeing copper wash in the grooves even with reduced loads.

If they didn't expand and fill the grooves, barrel life would be severely shortened by high pressure gas cutting between the bullet jacket and the bottom of the grooves.

I've shot .3075" diameter 30 caliber bullets in 7.65 Argentine M1909 Mausers rechambered to .30-06. Their groove diameter was .3112" and had copper wash in the grooves all the way from throat to muzzle with 10% reduced loads. If that doesn't show that bullets can obturate a few thousandths in diameter from lower peak pressures, well......

 

[spitballer]

Of course this means blow-by Bart B but doesn't this also affect cast bullet shooters trying to avoid fouling? Or FMJ's that don't seal as well? I mean, blow-by is a fact of life unless you're planning to completely coat the bore with a layer of copper and blast through it with every shot - why clean a new barrel after every shot when you're breaking it in if the tooling marks would do a much better job of holding this theoretical layering of copper? I'm just trying to offer a little practical help to an individual that obviously knows enough about longer barrels to consider slower, unlisted powders but not enough about reloading to invest a hundred bucks in a chrony to guide his experiments and protect his equipment. Obviously right hand twist pattern is from bottom left to top right as charges increase, and I'm just saying that I've had much better, longer lasting tight groups down left with a fouling shot on the right with the thin-jacketed bullets. This doesn't mean he can't max out every round and get a small group up on the right somewhere. He'll just build up a lot of heat and get flyers a lot faster IMO. FMJ's may be a totally different story I'm not too familiar with them but I can't believe they don't have at least as much blow-by as an optimally charged thin-jacketed bullet.

 

[Bart B.]

Deleted

 

[Bart B.]

spitballer, I've never heard of group centers moving clockwise as you state working up loads. Not from anybody. Therefore I think that's caused by something besides the rifle or ammo. If what you claim is true, how come it's never been put in print on/in any medium? What's the size in MOA such moving around clockwise? If it has been proved elsewhere and you know about it and didn't influence it, please forward me its location.

I've not seen any significant accuracy difference shooting 1 grain increments at 40 to 44 grains of IMR4064 under 168's in .308 Win cases in the same barrel with a 2.8" OAL for all shot at 200 and 300 yards. All test groups started out at the same place horizontally and each ones center changed a little in elevation from velocity differences.

All cast and jacketed bullets upset to fill the grooves and seal the bore. People have been cutting off barrels at the chamber mouth, re threading an chambering them for the same cartridge then getting the same great accuracy as before. There was no gas cutting nor erosion that would degrade accuracy in the bore caused by gas cutting caused by blow by. If there really was blow by, it would precede the bullet exiting the muzzle before the bullet did. Never saw any in videos of bullets leaving. If there really was high temperature gas blow by, jacketed bullets would have visible evidence of it between their grooves' engraved by the rifling that easily seen. That doesn't happen.

I have heard of shots walking in different patterns as barrels heat up, but that's typically fixed by squaring up the receiver face then shimming the barrel back in to headspace and clock the iron sights back in place.

That layer of copper is not theory. It exists. It's miminized if the bore finish is about 10 to 13 microinch. Any smoother or rougher and copper wash will get worse.

People getting best accuracy with any bullet typically get a barrel whose groove diameter is at least .0003" smaller than bullet diameter; I've shot some bullets almost .002" larger in diameter than the barrel's groove diameter; excellent accuracy. Starting with a clean barrel with maximum loads, they've shot 30 to 40 shot groups fired once every 15 to 20 seconds producing 1/3 MOA at 600, 1/2 MOA at 800 and 5/8 to 3/4 MOA at 1000. Those barrels went from ambient to very hot in the first 5 or 6 shots then stayed there. First shot from a clean barrel is often 1/4 MOA low but tests have shown that happens with a clean barrel producing lower muzzle velocities by about 10 to 15 fps than what they are 5 rounds later.

 

[spitballer]

spitballer, I've never heard of group centers moving clockwise as you state working up loads...

Okay, maybe the triangle is not the best analogy, but often rounds will land at an angle starting from bottom left and move up and to the right, velocity increasing with each shot. until bore dilation from heat causes them to drop, forming a triangle. The point being that my tightest, longest lasting groups seem to be lower than, and to the left of the fouling shot. Presumably this is from the right hand twist throwing them left when they exit the barrel off the bottom lands. When I charge the bullets enough to pass upwards and rightward through the center axis (point of aim or bore) they tend to roll left and right unpredictably. Therefore I keep the charge low.

Bart B my apologies for any misinformation I may have posted, I get carried away sometimes. I've listened to a lot of advice myself, and some of it's not so good. But I never intentionally mislead anyone. Copperhead says he's using a long gun with 68 gr Hornadys and I believe those are thin-jacketed bullets. The RE15 is a listed powder, comparable to H380 and probably a smart choice. I'm just trying to share anecdotal info to save him time and effort dialing in a load, but maybe I'm just sowing more confusion by bringing up subjects like drag and obturation. Therefore I'll simply urge anyone who's using soft bullets to take Lee's advice and "use the starting loads". Best of luck to Copperhead.

 

[Bart B.]

spitballer claims:

...often rounds will land at an angle starting from bottom left and move up and to the right, velocity increasing with each shot. until bore dilation from heat causes them to drop.....

...Presumably this is from the right hand twist throwing them left when they exit the barrel off the bottom lands.

So you think the bullet's riding on the lands at the bottom of the bore and because the lands at the bottom pointing about 4.4 degrees to the left at that point makes the bullets go only 1 MOA or thereabouts to the left. Then faster ones leave higher up on the left side of the bore and print higher 'cause the rifling there points up at the same angle.

And you also think the barrel heats up enough to expand (dilate) the bore diameter to larger than the bullet diameter and that's why this happens.

Do you think the bullet then rests at the bottom of the bore that's now much larger than .224" diameter so bullets only touch the rifling at its bottom?

hmmmmmmmmmmmmmmmmmm.

I calculated the angle of the rifling in that 22 caliber barrel and it's about 4.385 degrees; over 263 MOA.

Barrel steel increases its dimension about .000006" per degree F. How hot does that barrel have to get to increase its bore diameter of .219" at ambient to over .224"?

 

[spitballer]

How hot does that barrel have to get to increase its bore diameter of .219" at ambient to over .224"?

I don't know and I'm almost afraid to speculate. However, I would posit that the effective bore diameter will be determined more by fouling build-up than it will be from heat if I'm firing at a sustained rate of only 1 shot per minute.

My apologies to Copperhead if I've hijacked this thread. I'm not too proud to take good advice and I'm genuinely interested in Bart B's input here...

 

[Bart B.]

spitballer, your bore doesn't change diameter more than .0002".

As barrel steel increases dimension about 6 millionths inch per degree, dividing .0025" (rifling depth) by .000006 is 466 degrees F; the barrel temperature needed to enlarge the bore to over .224" so bullets wouldn't touch it. But with 500 to 2000 pounds of force on the base of the bullet all the way to the muzzle, that will easily upset the bullet to groove diameter all the way to the bore.

The rifling at the bore's top counteracts any tendency of the rifling at the bottom to move the bullet to the left. And the rifling angle on the left side of the bore is countered the same way by the rifling's opposite angle on the right side.

Bullets are fully engraved by the rifling all the way to the muzzle.

If you care to recover some bullets you think have behaved as you claim, check their rifling grooves. If they're all the same appearance, shape and depth in the bullets, that says they are fully engraved all the way to the muzzle.

Your bullet impact shift is caused either by your nonrepeatability in getting exactly the same position behind the rifle, or the barrel's poorly fit to the receiver. It's not due to the bore getting larger. It's the same reason several people will have different zeros for a given range with a given hand-held rifle and ammo; not because the way they look through the sights (a decades old myth) because light from the target and sights travels to the aiming eye exactly the same for everyone.

 

[spitballer]

Your bullet impact shift is caused either by your nonrepeatability...

Thanks for taking time out to respond. Your qualifications suggest that your input is more valuable than the sincere local gentleman who managed to get me to use 4198 propellant. All I know is what I see, and what I see is that the fouling shot always lands dead center, but not subsequent shots. But it sounds as if you're saying no, this is abnormal, a fouling shot does not normally land on either side of the main group, regardless of direction of twist. In a dead calm with perfect aim fouling shots should be landing up or down on the same vertical axis as subsequent shots. Therefore I should not be telling people to expect fouling shots to land to one side or other. Any tendency for fouling shots to land on one side or another indicates an abnormality with my particular rifle and is unrelated to direction of twist. Is it therefore safe to assume that others who have corroborated this phenomenon simply happen to have a similar abnormality?

 

[Bart B.]

Yes, others can have the same issue. But remember that people cause the most shot dispersion for a given load compared to that of the components. Having watched 8 or 10 people shoot the same rifle and ammo into 3/4" to 2" five-shot groups at 100 yards, yet the rifle's owner consistently gets sub 1/2" ones.

In a dead calm with perfect aim fouling shots may or may not be landing up or down on the same vertical axis as subsequent shots.

If your first shot from a clean barrel always shoots to point of aim, but the following ones scatter about in the same way, that's proof to me that your position probably hasn't changed since shooting the first shot, but the barrel's bending from heat expansion.

If subsequent shots tend to take different paths after the first one, that's probably caused by the barrel bending and your position changes.

Both are independent of the direction of twist.

Best thing to do so you can see what's really happening is to let someone else shoot your stuff, then see what differences there are.

 

[spitballer]

remember that people cause the most shot dispersion for a given load compared to that of the components...

Have to agree with you there. Old-timers have repeatedly said this and I certainly have room for improvement also. I'll try to illustrate with a couple of targets on another thread and get some more input. Stlll waiting on a 5mg check weight so it may not be this weekend. Thanks again for response, and again my apologies to copperhead for taking up so much space. - TH