DEWHighpower,
I haven't done more than skim the above posts, so some of this may be redundant: I think you might find this article a useful read. It's not Highpower Service Rifle shooting, but the practice methods and some of the loading information is applicable. The Froggy's Lube mentioned is no longer available commercially, but I was told it is just graphite powder in alcohol.
You may also find some useful information at Glen Zediker's site. He's written a lot of books on the subject of the AR, including a book on loading for competition. There are free articles there, too.
In general, if you have a good bullet and good brass and can dispense powder with good repeatability, which I assume you have already, there are four additional things you can do to improve precision for service rifle.
For brass sizing: once in awhile you hear of someone who needs to use a small base die to get his AR to feed. This is the exception, though, and I've never seen anyone having the problem give critical dimensions or the results of gauging the rifle and checking its timing, nor careful measurements of the case OD's at SAAMI key points. If you have one of these rifles, I would check the latter dimensions against the SAAMI drawing to see if your chamber was cut narrow with a worn reamer. You can also take it to Camp Perry during the Nationals and talk to the military armorers about it and see if they might be willing to gauge it.
If it turns out you have a SAAMI minimum diameter chamber and you own a generous sizing die, that could be the issue. A small base die will narrow the brass more.
For most of us, the commercial brass sizing allowance is adequate. That is, if you measure brand new commercial brass from head to shoulder datum diameter, you generally find it is about 0.002" shorter than a good quality headspace GO gauge is. Glen Zediker also uses this number. 0.002" shorter than your chamber's headspace length should be shorter enough. Sizing shorter than that will work and age the brass faster.
So, how best to go about that? There are a number of techniques. The Redding Competition Shell Holder set can be useful. A lot of folks use a comparator to measure the fired brass then size to set the shoulder back an additional 0.002". However, it is common (varies with pressure) to see a case spring back from full chamber length by 0.001" as it comes from the chamber, so setting it back 0.002" from chamber headspace takes only an additional 0.001". So if you have a headspace GO gauge and can shim it to find your exact actual headspace, that becomes a reference from which you can judge setting the shoulder back when sizing. You'll also likely find 0.001" of variance in the results. This is why the Redding Competition shell holders are in 0.002" steps.
To use the Redding shell holder set, put the holder with the highest deck height (0.010") in your press first and set the sizing die up normally. Measure what comes out on a few cases. If it is too long, go down in shell holder deck height size by the number of thousandths shorter your cases need to be. Try it again with a few more cases (not the same ones, as they will likely come out of the new setting a little shorter than those being sized for the first time.
Note that a number of shooters have found this type of sizing technique provides more accurate ammunition than neck-sizing-only. The thinking is that the small wiggle room both laterally and longitudinally allows the taper of the case shoulder to self-center the neck in the chamber when the firing pin drives it forward, improving bullet alignment and working even if your chamber isn't perfectly coaxial with the bore.
Another method of doing the above is to get shim rings that slip over the case after it is in a standard shell holder with 0.125" high deck. This works the same way as Reddings taller decks, but adds the step that you need to slip the washer over a case each time. Some have permanently soldered shims to the inexpensive Lee shell holders. Yous gets to pays your nickel and takes your chances.
For primer seating: If you are using a stick powder you may find the Federal GM205MAR primer made for the AR is best. You may also find the inexpensive Russian Tulammo KVB556M primer most consistent. The latter is a NATO spec magnum primer and it or the CCI #41 (also magnum) may be needed for some spherical propellants to perform best. The NATO and CCI primers ask you to compress the bridge by 0.002" to 0.006" or by 0.002 to 0.004". Compressing the bridge is how far beyond anvil contact with the bottom of the primer pocket you press the primer further. The military calls this reconsolidation of the primer. This optimizes sensitivity. Federal says their small rifle primers want 0.002" and their large rifle primers want 0.003" reconsolidation, period, but I have never seen signs of them being unable to tolerate a little more.
For primer seating tools, the most precise is the K&M Primer/Gauge tool. It is also the slowest priming tool in existence. This is because it first probes the individual primer pocket and subtracts the height of the individual primer to zero the indicator in one step. And then the case and primer are removed and put together at the top of the tool for seating in a second step. The dial indicator then directly reads how many thousandths of reconsolidation (the number of thousandths past zero) you have achieved.
A second and more practical method for most service rifle shooters is to uniform the depth of their primer pockets, and then seat the primers on the priming tool that presses the primers a fixed depth below flush with the bottom of the case head. For floating firing pin self-loaders, especially, this is the way to go as it mitigates the chance of slamfires. Such a tool is built into the Forster Co-ax press. Indeed, it is the only priming tool made that I am aware of that seats to a fixed standard primer depth below flush with the case head. Not even Forster's own Co-ax brand bench priming tool does it. Just the tool on the press. It is also possible to make a Sinclair hand priming tool do this with the right shims and ram adjustment.
One thing to be aware of is that the floor of a primer pocket gradually bulges outward with each reloading. It's because pressure inside the main case body builds faster than it can flow back through the flash hole to equalize. On trick commonly employed is to use a primer depth uniforming cutter to clean the primer pocket after each firing and thereby resetting the depth each time.
Alas, would that this were reliably so. The drill burrs are not as bad as punched burrs, but they are often present. I use a Dillon primer pocket swaging tool on once-fired military brass. It backs the web up with an anvil on the inside while swaging from the outside. Many is the time I've examined the swaged pocket only to find a burr has been bent over the flash hole by the anvil and has obscured a significant percentage of it. Once that happens, the deburring tool can't find the center easily. So, deburr lightly first, then swage.
Runout has been much discussed on this forum. The first step in minimizing is to be sure your resized necks come out of your sizing die straight and coaxial with the body of the case. Even an outside turned neck will not run true if an expander has pulled it off at an angle. That doesn't always happen, but it's not uncommon. So, what to do? One of three things:
Once you have a straight neck, you need to seat the bullet straight into it. Before he took it offline, German Salazar's Rifleman's Journal had a good comparison of seating dies. The Redding Competition Seater Die did best, and was the only one that actually corrected for neck runout a little bit. I've used these dies for over 20 years and found they really do cut runout a lot. If you buy one from the factory at full MSRP, for an additional $10 they will let you send them some of your resized cases and will custom fit the die to them. To me, the drawback to that is that it is then married to the chamber I resized them for, so I would only do this if I owned the reamer all my chambers in that caliber were cut with. If you don't chamber your own, you can send such a reamer to your custom smith with directions to use it.
An alternative exists. Get a standard RCBS seating die. The long stems allow the ram at the end to flex its lateral position a little, giving you some of the effect of a floating seater stem. This die can do remarkably well if the bullets start in straight. To get that to happen, you buy a Lyman M die for your chamber. Use it to expand the case mouth just far enough to start forming the little step its profile creates. Don't go far enough to get a flare, as you might want for a cast bullet. Set each bullet squarely into the step for seating, and let the RCBS seating die's crimp shoulder kiss it just enough to iron the step back out. You'd be surprised how little runout there is in a cartridge assembled this way.
Bullet pull is how many pounds of force it takes to pull a seated bullet out of the case. The release of the bullet during firing doesn't actually depend on this. During firing, the case neck expands away from the bullet until gas starts bleeding out at the front, at which point it stops expanding and leave the case mouth very slightly smaller in diameter than the rest of the neck. But up to that point, the speed and timing of that neck expansion is related to the bullet pull, so the more consistent the pull, the more consistent initial ignition seems to be. That makes for consistent velocity and pressure and barrel time.
So, how do you make it consistent? This is tough. Even commercial ammo doesn't pretend to be consistent over its life as the case neck and bullet gradually form a degree of bond that increases bullet pull and raises peak pressure. The best thing seems to be to minimize direct contact between the two. First, run a bore brush or a neck cleaning brush into your case mouths even if they are sparkling clean. The rough surface will mitigate bonding for awhile. Second, add a neck lube that remains between the bullet and the neck. The Froggy's lube mentioned earlier will do this. Just make a mixture of graphite and alcohol and Q-tip it around the inside of each neck and let it dry before seating.
If you shoot coated bullets, you have your lube already on the bullets, so if you have clean necks as from stainless steel pin tumbling, you can skip the inside neck brushing. You do need to burnish your case mouths, however, after trimming and chamferring. Per member Bart B's suggestion, I used a Dremel tool to polish an old EZ-out and chuck it in my drill press on low speed and touch freshly trimmed case mouths up against it. This dulls them so they don't scrape the moly coating off the bullets, something they do pretty completely without a burnishing step.
Resizing gradually work-hardens case necks, so if you have a consistent method of annealing cases, you may want to try doing it every time for consistency. But do take the time to check cases you have not reannealed for accuracy. You may find your gun likes the hardening cases for a load cycle or two or doesn't seem to care about this factor at all.
I haven't done more than skim the above posts, so some of this may be redundant: I think you might find this article a useful read. It's not Highpower Service Rifle shooting, but the practice methods and some of the loading information is applicable. The Froggy's Lube mentioned is no longer available commercially, but I was told it is just graphite powder in alcohol.
You may also find some useful information at Glen Zediker's site. He's written a lot of books on the subject of the AR, including a book on loading for competition. There are free articles there, too.
In general, if you have a good bullet and good brass and can dispense powder with good repeatability, which I assume you have already, there are four additional things you can do to improve precision for service rifle.
- Customize brass sizing for your chamber.
- Improve primer choice and seating.
- Improve cartridge runout.
- Improve bullet pull consistency.
For brass sizing: once in awhile you hear of someone who needs to use a small base die to get his AR to feed. This is the exception, though, and I've never seen anyone having the problem give critical dimensions or the results of gauging the rifle and checking its timing, nor careful measurements of the case OD's at SAAMI key points. If you have one of these rifles, I would check the latter dimensions against the SAAMI drawing to see if your chamber was cut narrow with a worn reamer. You can also take it to Camp Perry during the Nationals and talk to the military armorers about it and see if they might be willing to gauge it.
If it turns out you have a SAAMI minimum diameter chamber and you own a generous sizing die, that could be the issue. A small base die will narrow the brass more.
For most of us, the commercial brass sizing allowance is adequate. That is, if you measure brand new commercial brass from head to shoulder datum diameter, you generally find it is about 0.002" shorter than a good quality headspace GO gauge is. Glen Zediker also uses this number. 0.002" shorter than your chamber's headspace length should be shorter enough. Sizing shorter than that will work and age the brass faster.
So, how best to go about that? There are a number of techniques. The Redding Competition Shell Holder set can be useful. A lot of folks use a comparator to measure the fired brass then size to set the shoulder back an additional 0.002". However, it is common (varies with pressure) to see a case spring back from full chamber length by 0.001" as it comes from the chamber, so setting it back 0.002" from chamber headspace takes only an additional 0.001". So if you have a headspace GO gauge and can shim it to find your exact actual headspace, that becomes a reference from which you can judge setting the shoulder back when sizing. You'll also likely find 0.001" of variance in the results. This is why the Redding Competition shell holders are in 0.002" steps.
To use the Redding shell holder set, put the holder with the highest deck height (0.010") in your press first and set the sizing die up normally. Measure what comes out on a few cases. If it is too long, go down in shell holder deck height size by the number of thousandths shorter your cases need to be. Try it again with a few more cases (not the same ones, as they will likely come out of the new setting a little shorter than those being sized for the first time.
Note that a number of shooters have found this type of sizing technique provides more accurate ammunition than neck-sizing-only. The thinking is that the small wiggle room both laterally and longitudinally allows the taper of the case shoulder to self-center the neck in the chamber when the firing pin drives it forward, improving bullet alignment and working even if your chamber isn't perfectly coaxial with the bore.
Another method of doing the above is to get shim rings that slip over the case after it is in a standard shell holder with 0.125" high deck. This works the same way as Reddings taller decks, but adds the step that you need to slip the washer over a case each time. Some have permanently soldered shims to the inexpensive Lee shell holders. Yous gets to pays your nickel and takes your chances.
For primer seating: If you are using a stick powder you may find the Federal GM205MAR primer made for the AR is best. You may also find the inexpensive Russian Tulammo KVB556M primer most consistent. The latter is a NATO spec magnum primer and it or the CCI #41 (also magnum) may be needed for some spherical propellants to perform best. The NATO and CCI primers ask you to compress the bridge by 0.002" to 0.006" or by 0.002 to 0.004". Compressing the bridge is how far beyond anvil contact with the bottom of the primer pocket you press the primer further. The military calls this reconsolidation of the primer. This optimizes sensitivity. Federal says their small rifle primers want 0.002" and their large rifle primers want 0.003" reconsolidation, period, but I have never seen signs of them being unable to tolerate a little more.
For primer seating tools, the most precise is the K&M Primer/Gauge tool. It is also the slowest priming tool in existence. This is because it first probes the individual primer pocket and subtracts the height of the individual primer to zero the indicator in one step. And then the case and primer are removed and put together at the top of the tool for seating in a second step. The dial indicator then directly reads how many thousandths of reconsolidation (the number of thousandths past zero) you have achieved.
A second and more practical method for most service rifle shooters is to uniform the depth of their primer pockets, and then seat the primers on the priming tool that presses the primers a fixed depth below flush with the bottom of the case head. For floating firing pin self-loaders, especially, this is the way to go as it mitigates the chance of slamfires. Such a tool is built into the Forster Co-ax press. Indeed, it is the only priming tool made that I am aware of that seats to a fixed standard primer depth below flush with the case head. Not even Forster's own Co-ax brand bench priming tool does it. Just the tool on the press. It is also possible to make a Sinclair hand priming tool do this with the right shims and ram adjustment.
One thing to be aware of is that the floor of a primer pocket gradually bulges outward with each reloading. It's because pressure inside the main case body builds faster than it can flow back through the flash hole to equalize. On trick commonly employed is to use a primer depth uniforming cutter to clean the primer pocket after each firing and thereby resetting the depth each time.
DEWHighpower said:
Alas, would that this were reliably so. The drill burrs are not as bad as punched burrs, but they are often present. I use a Dillon primer pocket swaging tool on once-fired military brass. It backs the web up with an anvil on the inside while swaging from the outside. Many is the time I've examined the swaged pocket only to find a burr has been bent over the flash hole by the anvil and has obscured a significant percentage of it. Once that happens, the deburring tool can't find the center easily. So, deburr lightly first, then swage.
Runout has been much discussed on this forum. The first step in minimizing is to be sure your resized necks come out of your sizing die straight and coaxial with the body of the case. Even an outside turned neck will not run true if an expander has pulled it off at an angle. That doesn't always happen, but it's not uncommon. So, what to do? One of three things:
- Use only brass of the same neck wall thickness and buy the sizing die direct from Foster, paying the extra $10 to have them hone the neck out to the right size so your necks are minimally resized just enough to hold your bullets. That way you don't need and expander.
- Use a bushing type die the same way.
- Use a Lee Collet Die to size the neck and size the body separately with a Redding body die.
Once you have a straight neck, you need to seat the bullet straight into it. Before he took it offline, German Salazar's Rifleman's Journal had a good comparison of seating dies. The Redding Competition Seater Die did best, and was the only one that actually corrected for neck runout a little bit. I've used these dies for over 20 years and found they really do cut runout a lot. If you buy one from the factory at full MSRP, for an additional $10 they will let you send them some of your resized cases and will custom fit the die to them. To me, the drawback to that is that it is then married to the chamber I resized them for, so I would only do this if I owned the reamer all my chambers in that caliber were cut with. If you don't chamber your own, you can send such a reamer to your custom smith with directions to use it.
An alternative exists. Get a standard RCBS seating die. The long stems allow the ram at the end to flex its lateral position a little, giving you some of the effect of a floating seater stem. This die can do remarkably well if the bullets start in straight. To get that to happen, you buy a Lyman M die for your chamber. Use it to expand the case mouth just far enough to start forming the little step its profile creates. Don't go far enough to get a flare, as you might want for a cast bullet. Set each bullet squarely into the step for seating, and let the RCBS seating die's crimp shoulder kiss it just enough to iron the step back out. You'd be surprised how little runout there is in a cartridge assembled this way.
Bullet pull is how many pounds of force it takes to pull a seated bullet out of the case. The release of the bullet during firing doesn't actually depend on this. During firing, the case neck expands away from the bullet until gas starts bleeding out at the front, at which point it stops expanding and leave the case mouth very slightly smaller in diameter than the rest of the neck. But up to that point, the speed and timing of that neck expansion is related to the bullet pull, so the more consistent the pull, the more consistent initial ignition seems to be. That makes for consistent velocity and pressure and barrel time.
So, how do you make it consistent? This is tough. Even commercial ammo doesn't pretend to be consistent over its life as the case neck and bullet gradually form a degree of bond that increases bullet pull and raises peak pressure. The best thing seems to be to minimize direct contact between the two. First, run a bore brush or a neck cleaning brush into your case mouths even if they are sparkling clean. The rough surface will mitigate bonding for awhile. Second, add a neck lube that remains between the bullet and the neck. The Froggy's lube mentioned earlier will do this. Just make a mixture of graphite and alcohol and Q-tip it around the inside of each neck and let it dry before seating.
If you shoot coated bullets, you have your lube already on the bullets, so if you have clean necks as from stainless steel pin tumbling, you can skip the inside neck brushing. You do need to burnish your case mouths, however, after trimming and chamferring. Per member Bart B's suggestion, I used a Dremel tool to polish an old EZ-out and chuck it in my drill press on low speed and touch freshly trimmed case mouths up against it. This dulls them so they don't scrape the moly coating off the bullets, something they do pretty completely without a burnishing step.
Resizing gradually work-hardens case necks, so if you have a consistent method of annealing cases, you may want to try doing it every time for consistency. But do take the time to check cases you have not reannealed for accuracy. You may find your gun likes the hardening cases for a load cycle or two or doesn't seem to care about this factor at all.
