Reloading to minimize 'split'

[spitballer]

I've gotten a lot of good reloading advice from this site, especially from the senior members who are quick to point out that a shooter's technique is more important than minor adjustments. Nevertheless I seem to have made a breakthrough with larger groups, and I wonder if I can get any members to corroborate this:

Below are two photos of groups of 20 rounds, shot with a Rem 700 .223 with 12" twist and 55 grain Nosler Ballistic Tip bullets, Nosler cases, CCI #400 primers, and Varget.

The target at the top was from last week. Rounds were charged with 26.4 grains of Varget. Although it's hard to be sure at 400 yards just what is happening, there seems to be a barely discernable 1/2 moa split, with small groups left and right just north of the bull.

The lower target was from this morning. After bumping up the charge to 26.85 gains, the split seems to have been replaced with a single core group. Our senior members will be quick to point out that there are still a lot of rounds that are all over the map, but can anyone verify this phenomenon?

26.85 grains seems to be the lowest charge which will give me a distinct center group, but obviously it's still small: do more rounds collect in the center as the charge increased? Thanks in advance for any anecdotal data or advice regarding this.

 

[Doublehelix]

Don't have any advice, but I'd say that's pretty good shooting from a 55 gr .223 bullet at 400 yds!!! Nice!!!

 

[kingmt]

I can't help ether since I'm not a 400 used shooter. Wind changed directions somewhere between you& the target?

Looks like you probably could give me advice.

 

[Gtscotty]

Sometimes small changes in how you are holding the rifle and shoulder pressure can give you split groups. There may be something like that at work here... On the other hand it might just be random variance that looks like split grouping but really isn't.

 

[Blue68f100]

My experience with light bullets is that they move around more than you expect. Your target is not that bad for 400 yrds. I know many that would be very happy with your results.

I have not had any luck with Varget and light pills. But once I get to 65-69gr it shines. I've had better luck with Tac.

 

[Swampman]

Hodgdon shows 27.5 grains of Varget as max for a 55 grain Speer soft point.

Try working up slowly and see what happens. Sometimes you get to a point where everything "clicks" and group size drops.

On the other hand, that ain't bad shootin' as it is. What are the actual group sizes?

 

[FROGO207]

To verify this you could go back to the lower charge and re-shoot that distance again. I am betting that the other external factors are at work here, not the loads though. Have you done a full load work up with that rifle? Have you tried other bullet brands in that weight. +1 on the TAC with 55 grain Hornaday pills for accuracy this is what I found as well at 300m YD.

 

[Bart B.]

spitballer, I think your thinking and reading things about accuracy that only you seem to do.

How many small 3- or 4-shot bullet hole clusters are there in this target of 1965 M118 7.62 NATO National Match ammo? Out of all 270 shots fired at a target 600 yards downrange, isn't it possible, normal and statistically correct to see several small few-shot groups randomly happen at different places in the group?

Click on it to see more detail. Inner ring's 6", outer 12".

Does it seem plausible that it'll happen when someone shoots 20 shots at 4, 40 or 400 yards? That target is an excellent example of how rifles shoot bullets and the probability of any of them striking dead center on the point of aim at the group center. Most shots are inside half the group extreme spread of about 10 inches; yet some are further out. About two thirds in the 5" diameter, about one third in the 5" to 10" diameter part of the group. Statistical stuff at its best. Do that again and there'll be other few-shot clusters like those but in different places within the 20-shot group.

I've done it at 100, 200, 300, 500, 600, 800, 900 and even 1000 yards. Happened with 10, 15 and 20 shot groups.

If I shot a group like that, I'd concentrate on finding out why the 8 shots furthest away from group center went where they did. Forget about those 12 shots closest to group center. 'Tis my opinion that the ones furthest to the sides were caused by subtle cross wind changes neither you or I could see through your rifle scope. A 20X spotting scope to the side held still and focused at 300 yards would reveal those cross wind changes as mirage wrinkling across the field of view at different speeds. Those at the top and bottom are often caused by the rifle butt placed inconsistently against the shoulder as well a spread in down force on a rifle on a pad on a bench top. If the rifle's bolt face isn't squared up and fired cases from it are reloaded, that alone can cause a half MOA increase in group size at 400 yards, mostly horizontally.

Same thing happens with one round fired from a shotgun. How many few-pellet tiny clusters are in this pattern?
Click on it to see the detail.

 

[Hondo 60]

Don't have any advice, but I'd say that's pretty good shooting from a 55 gr .223 bullet at 400 yds!!! Nice!!!

I agree! If I shot either of those targets at 400 yards, I'd be dancing a jig!

How long did it take to shoot the split groups?
Did the barrel heat up?

Lots & Lots & Lots of "stuff" can cause your "issue".

I hope we've given you things to think about.

 

[farmerboy78]

+1 on tac, I use lc brass and 77gr cc and 23.6gr tac. Nearly one hole @ 100 from my white oak sdm upper

 

[au_prospector]

Statistically speaking, those targets are approximately the same. Well within one standard deviation for sure! I second Bart B., he is on the money. Too much noise in a 20 shot group. Nice shooting!

If I were you, and I wanted to 'fix' something, I would shoot several each 5 shot groups from 100 or 200 yards. What do those groups look like?

 

[spitballer]

I second Bart B., he is on the money...

...yes, although he puts me on the spot at times and challenges me to explain the facts. Thanks for the great responses but please keep in mind that overall group size is well over 1 moa for these targets, and this is the point.

I do in fact notice a very subtle pattern with Bart's first target, a pattern I found while experimenting with BL(C)-2 some months ago - looks like the pattern you'd find on a pair of dice showing the number 5 - four square outside with one in the middle. Anyone else see this? (I know, Bart, I'm seein' things again) Boy, now there's some shootin!

There are too many responses to respond individually but suggestions regarding powder selection are well taken: Varget is still a relatively slow powder even for a 30" bbl IMO and I may run into muzzle upset at some point although groups seem to be symmetrical so far considering barrel growth, and muzzle report is full but not particularly sharp Bart please don't ask me to explain 'full but not particularly sharp'

 

[Sunray]

"...do more rounds collect in the center as..." That has nothing to do with the powder charge. It's a probability thing.
"...26.85 grains..." That a typo? Digital scale set to 2 decimal places? .05 of a grain is virtually impossible to measure. Isn't necessary either. And your rifle appears to prefer the 26.4 grains of Varget.
Why are you testing loads at 400 yards? Just curious.

 

[Bart B.]

Spitballer,

Whats muzzle upset?

Do you think the fact that a 4-groove barrel caused those four corner clusters in that 270- shot target?

How many clusters would different groove counts cause? One for each?

Maybe one groove barrels would shoot one tiny cluster. They would have one land about 1/10th inch wide and .004" high. The rest of the bore at bullet diameter.

 

[spitballer]

"...26.85 grains..." That a typo?... Why are you testing loads at 400 yards?

Oh sorry I use an Ohaus digital scale that I bought some years ago to weigh aquarium chemistry. It only weighs in grams, and smallest increments are about .15 grains although they can be cut in half with a .005 gram weight. That particular load was 1.74 grams - 26.852306 grains.

I've been shooting at longer distances to give an expanded view of a group, but obviously all bets are off when the wind kicks up.

 

[spitballer]

Whats muzzle upset?...
Do you think the fact that a 4-groove barrel caused those four corner clusters...

Muzzle upset being excessive turbulence at the muzzle which throws the bullet off. Made worse by any rifling 'abnormalities' which channel gases in an asymmetrical fashion.

The corner clusters that I got were not caused by a four groove barrel when I was using BL(C)-2 so I would guess no, that your clusters were unrelated to the rifling configuration. Give me a break - at that distance? I'd say... harmonics?

 

[ArchAngelCD]

I have found the best accuracy using a 55gr bullet and Varget in the .223 has been 25.0gr. I'm shooting a Howa 1500 bolt action rifle with a 1:12" twist.

I'm not sure how much the slower velocity would effect bullet drop @400 yards because I never shot a .223 at those distances. It's not that I don't think the .223 is up to it, it's just that there are no ranges near me that reach out to more than 250 yards.

 

[Rule3]

I can not really add much as I do not shoot 400 yards but I will say, comparing 2 targets using different load with a difference of a over a week in between, just adds to many variables to the whole equation. Also, too many shots on one individual target.

That said, really nice shooting.

 

[Bart B.]

Spitballer comments on my picture of arsenal M118 ammo's 10" group at 600 yards.

Boy, now there's some shootin!

It's mean radius is 1.9". Specs are 3.5" mean radius. Too bad they used 4 different lots of bullets, not all of equal quality; all mixed up together for that Nat'l Match lot. A match grade barreled Rem 700 or M1903 action profiled to fit a Mann rest was used.


It shot about 15 inches at 600 in the best rebuilt service rifles. Not so good compared to the same rifles shooting commercial match ammo into 4 or 5 inches at 600.

Regarding "harmonics" being the cause of those clusters at 4 corners about center. A barrel's muzzle harmonic frequencies which are non-linear multiples of its resonant frequency are the most repeatable thing amonst all the variables involved. The test barrel that shot those 270 bullets was very repeatable in its resting position in the Mann rest holding it. I've seen several National Match lots' test groups of some 270 or so shots and they all have a few clusters of bullet holes; all at random places in the group relative to group center. You can generate the same thing with a computer program plotting where 250 shots fired will look like this:

How many few-shot clusters are in that group and where are they relative to center?

 

[spitballer]

I'm seein' five clusters and two subclusters [] all pretty much along the usual "X" axis but - what's most significant to me is the the loose cluster directly above the bull and the two denser subclusters lower left and right of it that form a diamond on a vertical and horizontal axis. High and low groups on the center vertical axis are seldom seen on my targets, in fact I can't recall ever seeing this.

Most of the other asymmetrical stuff looks familiar so I would guess that it's also right hand twist?

 

[spitballer]

It's not that I don't think the .223 is up to it, it's just that there are no ranges near me that reach out to more than...

...I was convinced that even at 100 yds a quality target load could be dialed if I just give up cherry picking and 3-5 shot groups. Bart's suggestion that 20 and 30 shot groups are more revealing was right on IMO, but I suspect most of us never do this with thin-jacketed varmint bullets because they're a lot trickier than FMJ's when it comes to sustained fire...

 

[Bart B.]

Bart's suggestion that 20 and 30 shot groups are more revealing was right on IMO, but I suspect most of us never do this with thin-jacketed varmint bullets because they're a lot trickier than FMJ's when it comes to sustained fire...

Hornady and Sierra shoot dozens of 10-shot tests during production runs of their 22 caliber varmint bullets. At 200 yards, those groups are mostly under an inch with shots fired once every 10 to 15 seconds apart. Production runs are a few thousand bullets and accuracy tests stop when the run stops. Bullets come out of the last shaping die about one every second.

What's tricky about that? Most match bullets are thin jacketed to get more lead in them to raise their BC's. That's also why they're more subject to splitting apart if spun too fast. Rifling engraving their jackets weakens them. Each bullet is only fired once so they don't know their rate of fire therefore perform equally across all reasonable rates.

Part of the cost of bullets pays for new precision barrels installed, reloading tools and other components to test them during production runs.