.308 precision reloads

[Eppie]

I'm getting closer to my goal of .308 precision reloads, but I'm not there yet, so I'm looking for place to improve accuracy.

I do the following steps:
1. Resize the brass (no ball expander)
2. Expand the neck with a Lyman Neck expander die
3. Turn the brass necks on a Gracey Neck Shaver

Now I've discovered that the neck expander mandrel is .306 but the Gracey neck shaver mandrel is .3035. So there is .0025 difference that may be impacting accuracy and consistency of my reloads. A micrometer verifies that the neck thickness varies.

I believe that if I have the Lyman neck expander mandrel ground down to .304 and reduced the variance in the case neck size the neck shaver would do a better job and improve accuracy and consistency. Am I on the right track? Is .304 a good target or is it too tight?

Thanks for your help.

[603Country]

How good are you shooting right now? Is the ammo the limiting factor in your shooting. Is more extensive case prep really going to get you more accuracy?

[Eppie]

Hi 603Country,
A picture is worth a 1,000 words, so here:


I you can see in the first group ,when I use the Federal Gold Medal Match ammo, the group is substantially better than my reloads. As I am planning to start shooting in long range matches in the future, every little bit matters.

[Unclenick]

Several thoughts come to mind:

First, don't change the neck expander. .306" or even .307" should produce neck tension closer to Federal's.

If you are going to shoot a ball powder like 760, try CCI Magnum primers or the Federal 215M primers. Those older deterrent coating formulations are harder to light up than modern ones such as those in the Ramshot line. You may even want to try deburring the flash holes to get ignition to improve.

You might also reconsider that powder choice altogether. If you insist on staying with a spherical, you could try 748. That's the powder Winchester Supreme Match ammo was loaded with under a 168 grain match bullet. Accurate 2520 is also liked by some. I've never heard of 760 being liked for match shooting with that bullet weight in the .308.

I've used both 748 and 2520 and found I had to go to more trouble with both to get accuracy to approach that of stick powders like 4064 or Varget or Reloader 15. Even though spherical powders meter more uniformly, their more difficult ignition makes them prone to higher velocity variation than a less uniformly metered stick. Federal Gold Medal Match with 168 Grain MatchKing used 43.5 grains of IMR 4064 originally. It currently uses Reloader 15, but I haven't weighed the quantity. The old GMM 168 I pulled had a 0.4 grain spread in charge weight of the 4064.

I would be checking bullet runout. Some chambers seem to be much more sensitive to this than others.

If you are going to shoot long range, I would also switch to the 175 grain Sierra MatchKing. The 168 grain SMK, with it's 13° boattail, tends to become dynamically unstable in the transonic range (somewhere around 700 yards in most .308 Win loads).

One year I attended the Long Range Firing School (LRFS) Mid Tompkins used to hold at the end of the National Matches. At the first firing exercise at 800 yards, over half the students (myself included) had brought ammo using 168 grain MatchKings. Moans, groans and curses could be heard up and down the line as none of us could stay on paper (a 6 foot square LR target) and reports of keyholes came back from the pits.

That year, Sierra's Kevin Thomas was attending the LRFSl and he explained the 168 grain SMK had been designed for 300m International Rifle, and the fact it shot well to 600 yards had been a bonus for the company. But the 175 grain MatchKing with 9° boattail was designed for long range. So, at lunch, we all ran out and got commercial ammo loaded with the 175, and after lunch everyone got on paper and stayed there, and no more keyholes were reported.

I've heard people tell of successfully shooting the 168 to 1000 yards. Interestingly, it has always been with slower barrel pitch than the 10" twist I and most others at the LRFS had, and with which the bullet should theoretically be more stable. I think it may partly have to do with side wind which was gusting to 10 mph at the school. The other time I had trouble with the 168's was at Gunsite where we fired at a 748 yard popper in a steady 20 mph 3:00 wind, and nobody could hit that popper consistently either, with the 168's whizzing off diagonally left and right. But it may also have to do with the yaw of repose and spin drift when spinning faster. I don't know. I just know to consider those bullets trouble at over 600 yards.

For your Gracey outside neck turner, that mandrel diameter sounds too loose. Check with Gracey, but I expect you want it about 0.001" smaller than the ID of the neck you are turning. Since you size without using an expander, your necks may be that small coming out of the sizing die, which would then be the time to trim, before expanding. If you are using a bushing type die, you can get bushings that will make them that size.

To see if the brass is the issue, invest in one box of 100 Lapua .308 cases. Their case capacity is similar to Federal's but they are the best .308 brass made right out of the box. No flash hole burrs. Necks walls even within 0.001". Best hardness for durability (Federal brass is famously on the soft side, limiting your load pressures).

Be sure you are bump sizing: setting the case shoulder back just 0.001"-0.002" from the size they are when you extract them. That seems to allow the most and best self-centering of the case in the chamber.

Get or borrow a chronograph. Every time you make a change, check to see what happens to the velocity standard deviation. For long range you want to try to get the standard deviation of 10 rounds to under 10 fps. Depth uniforming your primer pockets and using the primer seating tool built into the Co-ax press can help with this.

Nick

[Eppie]

Unclenick your advice is golden as usual.

I will leave the mandrel alone, instead I will modify the thickness of the neck shaver from .016 to .015 and see if that improves/degrades accuracy. I can always set it back.

I'm sort of committed to Winchester 760 because I have around 24 lbs. of it from when I was using the LnL AP press. I'm also committed to the Federal 210 because I have 5,200+ left.

I'm using the 175grain Sierra for the exact reasons you outlined. Last week I was observing a 800 and 1,000 yard practice and the one guy shooting the 168 key holed every time. The only reason they didn't stop him was because the radio in the pits wasn't working.

I did buy 200 Lapua cases, the first 20 I used performed a little worse than the Federal, which I found surprising. So to avoid more confusion I set them aside for the time being and concentrate on the Federal that I have lots of. I know I will eventually switch to them, but first they have to prove their worth to me.

I'll start using the Oehler 35P on my next trip to the range. Maybe then I can start getting more insights.

[A_Gamehog]

Maybe it's just me, but to neck turn brass for a factory chamber is not needed.

[Unclenick]

A_Gamehog,

It depends on the chamber. A couple of the more knowledgeable guys at the CMP forum found outside neck turning makes a difference in M14's. Glen Zediker also does it for service rifle match loads. It's all about bullet alignment in the bore, and some chambers are more immune to tilted bullets than others (or, rather, are better able to straighten a tilted one on the fly than others). Ironically, it is tight benchrest chambers that tend to be most immune to bullet tilt, and looser chambers in which it often has a bigger influence. It's one of those things you have to try in order to find out if it matters much to your gun or not, but there's no universally applicable rule.


Eppie,

The ignition issue is significant enough with the aging Western Canon series of powders from St. Marks that in 1989 CCI changed their magnum primer formulation specifically for firing them. These powders are WC748, WC760, WC844, WC846, WC852, and WC869. They are sold in canister grade for reloading as Winchester 748, Winchester 760/H414 (both the same powder in different brands), and Hodgdon H335, BL-C(2), and H380, and US 869, respectively. The slower burning the powder, the more it needs the warmer primer to get started burning in a consistent fashion, and 760/H414 is the slowest save for US 869.

In your shoes I would get 100 of the CCI primers and work the load back up and see if you get any improvement. I would also get a single pound of one of the other powders I mentioned to use with the 210M's, and then work up loads with it to see what happens. This is to get a sense of the rifle's potential with handloads and the 175 grain bullet.

Unfortunately, I fear you're handicapping yourself by having the combination of a hard-to-light powder that is slower than the usual match powders used in the .308, and a primer milder than those normally optimal to fire it. There is no way to guarantee you can overcome those combined factors to get that particular combination to shoot up with the Federal ammo.

The ignition uniformity issue, assuming you have it, will not be a matter of failures to fire, but rather of irregular ignition delays on the order of several milliseconds which, like having irregular lock time, tend to allow small disturbances from your trigger release and other position control factors to have variable effect on the exact position of the muzzle at the time the bullet clears it. The good news is that this sort of ignition issue generally corresponds to muzzle velocity variation, so the chronograph should inform you about it.

[Eppie]

Unclenick said: Unfortunately, I fear you're handicapping yourself by having the combination of a hard-to-light powder that is slower than the usual match powders used in the .308, and a primer milder than those normally optimal to fire it. There is no way to guarantee you can overcome those combined factors to get that particular combination to shoot up with the Federal ammo.

I'm slowing coming around to the realization that I may have to try different powder, especially since I no longer use the progressive press. That was the main reason I was using ball powder.

Thanks again.

[Rimfire5]

I get the best results with my 2 Savage Model 10 .308s with Vihta Vuori N140 powder and almost as good results with H4895.

I have shot 150, 168, 175, 190, and 200 grain loads under 0.5 inches with one rifle and all but the 190 and 200 grain bullets with the other rifle ( I haven't tried the 190 and 200s with that rifle yet.)
The N140 yields slightly more accuracy, I think because it meters better.

I know both powders are difficult to find these days but either will do just fine. Reloader 15 is slightly less accurate than the N140 and H4895 but works well. I would have expected Varget to have been a very accurate choice, but I have never gotten Varget to shoot as well with either rifle for some reason.

[Bart B.]

While there's all sorts of ways to assemble handloads or reloads, I'll address the one thing that, in my opinion, is seldom done to asses the accuracy of such loads in ones rifle. Testing for accuracy.

Those 5 few-shot groups Eppie posted are too close to the same size to significantly tell which load's the most accurate. Had each group at least 10 shots, there would probably be a more noticable difference. 20 shots per group are even better.

Want to find out how significant few-shot groups are? Shoot five 3-shot groups of the same load. If all five are not within 10% of the same extreme spread, not enough shots per group were fired for all of them to be meaningful. The largest one's probably the most representative of that load's accuracy that can be counted on. Largest groups show what happens when all the variables for that load are at their maximum limit. The smallest groups are caused by one of two things; all the variables are at zero or they cancel each other out and these are what benchresters get excited about but they don't know which one it was. An example of cancellation is the muzzle axis is a bit to the right of where it should be when the round's fired and the bullet's unbalance makes it jump to the left as it exits. Another is when testing at long range, a bullet has a higher than average muzzle velocity but its unbalance causes more drag so it strikes lower on target than it otherwise would.

All loads will occasionally shoot a few bullets into a very tiny group. But all the rest are larger. And the composite of all few-shot groups fired is larger than the biggest single group because the centers of each few-shot group's are not all at the same place relative to the aiming point.

Most folks will shoot smaller test groups with a given rifle and load when they're slung up properly in the prone position with the stock's fore end and toe resting on sand bags than using the traditional bench position holding the rifle against their shoulder as its fore end rests atop something on the benchtop.

Test your own accuracy by borrowing a friend's rifle and ammo he regularly shoots sub 1/3 MOA groups at 100 yards and see if you can do likewise.

[pathdoc]

One wonders if, had you fired a five shot group with the factory match ammo, a couple of fliers might not have opened up the group wider than a couple of your handloads. Groups 3 and 4, for example are ragged holes plus fliers. Group two? Take away the two outliers and you're still doing better than the match ammo (the bullet holes are all touching).

Ten shot groups will ccertainly give you a more statistically representative sample. Twenty may be going overboard.

[Bart B.]

Pathdoc, the more rounds fired in a group, the more statistical significance it has. Arsenals testing military rifle ammo shoot 200 to 300 shots per test group. They get almost 100% confidence it represents where all fired shot will go; that's what they want to know.

[Jimro]

Bart B.

The Army tests 200-300 rounds per lot. The Navy can do the same statistical analysis with a single 50 shot group.

The Army measures mean radius, the Navy measures extreme spread. That is why the Army specs machine gun ammo and the Navy specs all the Sniper ammo SOCOM uses...

Makes me weep for my service some days.

Jimro

[ronl]

I would agree with the change of powder to get better groups. I've tried 748, BLC-2, and 335 for .308, but they never came close to the groups achieved with IMR 4895, 4064,RL-15 and Varget. In my instance, Varget was slightly more accurate overall. What was most important in discovering the most accurate load in my particular rifle was determining the leade my rifle likes.

[Bart B.]

Jimro, I don't think a 50 shot group's extreme spread will have the same statistical analysis as a 250 shot group's mean radius. There's different objectives for each method. I've seen some of Lake City's match ammo groups of 250 or so shots with mean radiuses in the 2 inch range but extreme spreads of 8 to almost 15 inches at 600 yards; the accuracy spec is 3.5 inch mean radius average. The 1965 7.62 M118 National Match lot had a 1.9 inch mean radius but a bit over 11 inches extreme spread on its 600 yard target; that target had most shots clustered tight and small in the middle, but those wide ones made the extreme spread huge. Most likely they were caused by poor bullets than any other component issue.

I do think extreme spread's a better way to measure. It lets one know the most the shooter can expect most of his shots to miss the point of aim. Mean radius is only what the average miss distance will probably be. And both are much better than average group size for a few 3, 5 or 10 shot groups' extreme spreads.

[pathdoc]

Bart - yes, I agree, but the arsenals have essentially limitless resources and cost is no object. The average shooter doesn't, cost is a vital limiting factor, and they must make a more restricted decision on where a sane place is to stop.

[Bart B.]

pathdoc, arsenals have limited resources; loading machines, for one type. And they also have cost limits.

'Twas proved decades ago that weighed charges of IMR4064 powder shot .30-06 match ammo 30% or more smaller test groups than metered charges of IMR4895. They stuck with IMR4895 because its use gave satisfactory accuracy as well as costing less to load.

Arsenals' ballistic engineers also knew commercial match bullets shot more accurate than their 172-gr. FMJBT bullet, but that old bullet was a lot cheaper to make with tooling reminiscent of that used back in the 1920's when that bullet first came about. It wasn't until the 1980's that a limited amount of 30 caliber Sierra HPMK's were put in their match ammo.

'Twas also well known that ball powder produce less accurate ammo than extruded powders. But the gummint decided Remington had operated Lake City Army Ammo Plant too long and let Winchester take over. Their ball powders were put in the M118 7.62 match ammo and its poor accuracy was disliked by all the folks using it in service rifle matches.

The big difference in accuracy attained by top level competitive shooters compared to all the others is not the components they use. It's their rifle hardware; they use good barrels properly fit to correctly assembled rifles. And they know how to test loads with the minimum amount of rounds fired. One very important thing is, they know how to reduce human error in accuracy testing. The components they use are those that have a good track record and their reloading tools are the same. Expensive reloading tools don't produce any better accuracy than less costly ones if the correct ones are obtained in the first place; one needs to know what's good and what's not. There's little difference in their component suite for a given cartridge and most use the same load recipie for every barrel adjusting it only for different lots of powder in some instances. And a lot of them get virtually the same accuracy with brand new cases as they do with totally prepped new ones fired a few times.