Lubing for consistent shoulder setback?

[Shrinkmd]

I recently received my Redding Instant Indicator, and I used it to check the chamber on my old Bushmaster XM15. I used some 6x brass, which read 0.007 to 0.008, so I guess we're within spec, less than 0.010 according to the die instructions. I also tested some once fired brass from my rifle, which only read 0.005 to 0.006, so multiple firings in the chamber definitely showed a difference.

I tried adjusting it to set back the shoulder by about 0.003, based on various posts and advice, although the Redding instructions suggest more, 0.004-0.006 Depending on how much lube I use, however, this can vary from only setting back by 0.002 up to 0.005, depending on how often/much of the Imperial Sizing wax I rub on. There were even a few times where I skipped adding wax, and just used the wax left on my fingers after a few cases. The sizing didn't feel as smooth, but still not sticking any cases in my die. On that one, it only set the shoulder back by 0.001 or maybe 0.002, so I lubed it up some more, to increase the setback to at least 0.003 on those pieces of brass.

When I looked at the case sized to 0.003 smaller, it looked great in my Wilson case gauge, sticking out a little more than I had it set previously, just at the top of the gage.

To try and get my setback most consistent, it looks like I should try to use the same amount of lube every time. I will work on my technique, and possibly adjust the sizing die a bit. I guess it is more important to make sure that every round has been sized enough so that there is no sticking, rather than worrying that a few might be set back 0.005 I guess there is always a range for these things, but I next plan on getting a Giraud trimmer, and since the case length functions off the shoulder, I want to try and get things as consistent as possible.

Any other advice or thoughts on how I'm approaching this?

 

[243winxb]

get my setback most consistent

Use redding competition shell holders to better control bump.

When the shell holder contacts the bottom of the fl die, it acts as a stop.

A 223 shoulder can be set back .006" from the firing pin strike. I would not worry to much about shoulder bump.

An auto loader (M16) bolt slamming on a long head to datum cartridge can set the shoulder back .001" to .0015"

 

[Slamfire]

I tried adjusting it to set back the shoulder by about 0.003, based on various posts and advice, although the Redding instructions suggest more, 0.004-0.006 Depending on how much lube I use, however, this can vary from only setting back by 0.002 up to 0.005, depending on how often/much of the Imperial Sizing wax I rub on. There were even a few times where I skipped adding wax, and just used the wax left on my fingers after a few cases. The sizing didn't feel as smooth, but still not sticking any cases in my die. On that one, it only set the shoulder back by 0.001 or maybe 0.002, so I lubed it up some more, to increase the setback to at least 0.003 on those pieces of brass.

Reliable, safe ammunition is the primary consideration in all reloading activities, and for gas guns, premium chow is critical for function. Lets start with the assumption pressures are safe, then what you really, really, want in a gas gun is 100% function. That requires ammunition that is smaller than the chamber. Ammunition that is a crush fit to a chamber will cause an interference fit, the bad situation is on the right:



Some of the thoughts behind cartridge design:



So, for a 223 to be used in a gas gun, I recommend small base dies, to reduce the case as much as possible, for initial clearance on chambering, and clearance during extraction. In so far as base to shoulder distance, because cases vary so much in work hardness, you are never going to get perfect base to shoulder consistency after sizing. Maybe when cases are new, out of the extrusion dies, but not after firing. So, for clearance between case shoulder and chamber, I recommend setting the shoulder back about 0.003", on average. The average should, to repeat should, keep all the rounds from being a crush fit to the chamber.

Of course, why not increase the headspace further? There you will get into problems with case head separations. With a dry case in a dry chamber, the case neck sticks to the chamber during initial combustion, and as pressures build, the side walls stretch to allow the case head to reach the bolt face. Too much clearance between shoulders and chamber will result in this:



This can be fixed by lubricating the cases, something I do when fireforming cases. In fact, oil lubrication was something that was done on many pre WW2 machine guns because manufacturing tolerances of the era were insufficient to maintain chamber headspace. This era of firearm history has been forgotten, and I think deliberately, but the reasons for oiling cartridges are technically, mechanically and physically correct and does not involve magical thinking:

The Machine Gun History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons by George M. Chinn Lieutenant Colonel, USMC VOLUME I OF FIVE VOLUMES

Chapter 8 Nambu Automatic Weapons page 353

All Nambu machine guns were gas operated and air cooled with many radial fins giving more surface for cooling. The earlier models had rectangular gravity oil reservoirs so that as rounds were fed into the feed opening they engaged a spring-loaded lubricator. This action caused oil to flow through perforations onto the cartridge cases. Such lubrication was needed because manufacturing the components to such close tolerances as to permit a workable head space had not been possible at the time. The oil permitted the cartridges to slip back against the bolt until lock clearance was taken up, thereby eliminating the danger of a ruptured cartridge case

Chapter 9 Revelli Aircraft Machine Gun page 354

The Italian Air Force during World War I was so desperate for an adequate rifle-caliber machine gun of native origin that it ordered the lightening of the water-cooled 1914 model Revelli. This was accomplished by the removal of the water jacket and use of an air-cooled barrel with longitudinal ribs. It not only gave more cooling surface but also strengthened the barrel, cutting down dispersion. The rate of fire was increased by use of ammunition more thoroughly lubricated by means of a built-in oil pump.

Chapter 21 Breda Machine Gun page 416

A large oil reservoir was built into the top of the receiver, directly over the feedway. This lubricator was operated by the recoil and counter recoil movement of the barrel and barrel extension, squirting oil with each complete cycle on the rounds then being positioned on the floor of the feedway.

Page 419

Like all Italian machine guns oil was used freely on the ammunition since head space was not adjustable on the weapon. The fixed relation between the front face of the breech-lock receiver and the gas port in the barrel made impossible rotation of the barrel in order to advance or retract the chamber for correct head space. The oiling of the ammunition was resorted to in this case in order to compensate for the above condition.



I get involved with arguments with Hatcherites all the time over these mechanisms.
for example: 300 H&H https://www.thehighroad.org/index.php?threads/300-h-h.843075/
Because they were told case lubrication is dangerous, and the human tendency is to believe something is true when an authority figure tells you something is true, Hatcherites believe what they were told and ignore anything that contradicts this narrative. Which is another part of human psychology, we perceive the world as we want to see it. We only see what we want to see, we discard those things that don't fit the narrative in our minds. But, the historical record shows, Hatcherities are barking mad.

A gunsmith bud left the slzing lube on the 308 cases and never experienced a case head separation in a M1a, and he shot the same brass for an entire shooting season. I copied it, and my brass lasted an obscene amount of reloads. I took one set of 308 LC 22 or 23 reloads, in a M1a, without a case head separation. I have left case lube on 223 cases, to improve extraction, but it also will prevent case head separations in brass with excessive chamber headspace.

So, I recommend, set your case shoulders back 0.003" and don't worry about shoulder clearance. If you find cases where the shoulder is set back 0.005" or more, leave the lube on.

 

[Walkalong]

Different cases will resist sizing differently. There will always be a small spread in how the shoulders come out. Mixed range brass can have a pretty wide spread, while top quality matching cases will have very little. Use enough lube to not stick a case and don't slather it on and you'll be fine.

my old Bushmaster XM15

I do an average of .003 setback for auto cases like 300 BLK & .223/5.56 for an AR. Some will be a hair more, some will be a hair less, but all will function and all will be safe as far as head clearance and potential case head separations are concerned.

 

[Shrinkmd]

Thanks for the info. I've successfully reloaded 1000+ rounds with my dies and no feeding issues, so I think I'm ok without the small base die. Is it ok to always leave the lube on? Previously I used Hornday One shot and left it on. I haven't put any sizing wax inside the necks, since I'm using the Redding carbide ball. I haven't bothered trying to wipe it off, good to hear that it may be extra helpful in case of a case head separation. I tried the paperclip and I've been looking for rings near the case head, and so far this 6X brass looks pretty good. I can see a "line" where the sizing die stopped, but it doesn't look like an actual bring ring.

 

[Slamfire]

Thanks for the info. I've successfully reloaded 1000+ rounds with my dies and no feeding issues, so I think I'm ok without the small base die.

My Garand/M1a gunsmith would tell me about match rifles, of all calibers, that he would build and send back to the owners. Often, especially with the gas guns, he would get a call back about the rifle not extracting. It was always due to brass fired in a different chamber and sized with a standard sizing die. I use a small base die in every caliber I can get a small base die. But you know, that surplus machine gun brass, or brass fired in a Zeppelin hanger chamber, a small base die does not have the reduction capability to reduce the stuff down to where it will reliably extract from a gas gun. That is where industrial equipment, which will positively reduce the case head, such as this roll sizer, is called for:

Case Pro 100



http://www.casepro100.com/

All yours for $893.00, extra sizing dies, extra.

Is it ok to always leave the lube on? Previously I used Hornday One shot and left it on. I haven't put any sizing wax inside the necks, since I'm using the Redding carbide ball. I haven't bothered trying to wipe it off, good to hear that it may be extra helpful in case of a case head separation.

A Hatcherite will read your statement and see nothing but wavy lines on the screen as they can't process the idea that you did not vanish in a puff of smoke. Of course you can leave the lube on.

There have been a lot of lubed cartridges. This is a famous one, the 276 Pedersen. It was coated in ceresin wax.



In fact for my Garand and M1a ammunition, I coated my cases with Johnson paste wax and once the stuff had dried, I buffed the rapid fire rounds. The slow fire stuff, it did not make any difference how crusty the paste was was, but in cold weather, crusty, waxed ammunition would sometimes cause a bolt over ride. No one shoots the M1a in XTC competition, not like when I was shooting. The advice at the time was to fire the round five times and dump them, because the case heads would separate. This is waxed brass from my rifle, stuff that had neck or body splits, but no sidewall thinning:



Back in the day, I would tell fellow shooters about my case life experiences, and they all thought I was nuts. Nuts because cases could not last that long in a M1a, and nuts because everyone knew that lubricated cases dangerously increased bolt thrust. Sometimes, you gotta to recognize that conventional wisdom is all bunk and that the "smart guys" in the shooting community are barking mad.

When it comes to lubricated cases, the in print press has pretty much drilled a hole in their heads, and sucked half their brains out. There are a number of lubricated rounds still on the market. This weapon fires a lubricated round



Gunwriters call it a "polymer coated round" because they know Hatcherites would foam at the mouth if they read that this round is lubricated, and, Hatcherites are too stupid to know that oil, grease, wax, vasoline, hair gel, teflon, etc, are all polymers. It is just not worth the time or effort for a profit maximizing publication to argue with delusions of ideologues. In fact, you have to read George Frost's book "Making Ammunition" to find that aluminum case ammunition is wax coated, so the stuff will extract. Remember the comment I made about Hatcherites seeing only what they want to see?, the grease on the outside of match 22lr ammunition will not register in their brains. The good stuff is coated from tip to rim with grease, and you can feel it. When I have brought this up, I get nonsense about rimfires essentially operating in a different physical universe. "But that's a rimfire!". Yes, it is a rimfire and it follows the same Newtonian laws as centerfire cartridges, in the real universe.

No Hatcherite has ever explained how caseless ammunition firearms can work, if case friction is essential to reduce bolt thrust



I have not asked a Hatcherite for his theory on how these cartridges work. If bolt thrust reduction is directly proportional to the surface area of a cartridge, then, these must be dangerous, right?





Case friction between the plastic and the case head has always been a problem with these two piece cartridges, in the past, the front of the case stays in the chamber while the base is extracted. The joint is the weak part of these two case designs.

There are a couple of real issues with wet lubes that dry wax lubes don't have. Wet lubes, that is case lube, greases, oil, will collect dirt. This was one of the major concerns that the US Army had, prior to 1921, and you can read it in Captain Crossman's article titled "Grease" Captain Crossman goes all Apocalyptic about the red dust storms in Georgia at the beginning of his article. Everyone was dipping their bullets in grease because grease absolutely positively prevented cupro nickel fouling. But, dum-dum's would drop their greasy ammunition in the dirt, and would not wipe off the grit, before chambering the stuff in their Army loaner rifle. I am certain the Army was very unhappy with the number of rifles with scratched chambers and scratched barrels that came back after matches. Dry lube rounds will collect dirt, but you don't have grease or oil over your hands after handling them. I use wet lubes when I have access to water and soap. I don't like being greasy for the rest of the day. The best lubricated case pictures I take have all been at CMP Talladega, where at each end of the firing line, there is a bathroom with hot and cold running water! Wow! Such luxury, clean hands, clean face, for decorum's sake, no need to pee behind the berm when the women are around....



After firing tens of thousands, perhaps, a hundred thousand lubricated cases, primarily with shallow shouldered 30-06, 270's, 308's, and cases of match 22lr, (maybe 5 to 10 thousand 45 ACP rounds), I got a shoulder dent. One day, at CMP Talladega, a cold day, I got shoulder dents on these 6.5 Swedes. I don't know why. Don't recall seeing the dents till I was done. Maybe a bug got in the chamber, or a booger. I have sized these cases and I will shoot the dents out, with a thin layer of lubricant.

I tried the paperclip and I've been looking for rings near the case head, and so far this 6X brass looks pretty good. I can see a "line" where the sizing die stopped, but it doesn't look like an actual bring ring.

Eventually you will have a case head separation, recognize the difference between it and the sizing die ring, and all will be well.

See the scratches, even a good sized case stretch ring can be hard to locate. I wanted to make sure I found the deep side of the ring before I sectioned the case.

 

[243winxb]

Using an RCBS lube pad, i dont think i get lube on the shoulder of 243 or 223?

I guess i dont get how lube has an effect on the shoulder bump.

 

[Blue68f100]

I found that if I anneal the brass prior to sizing the shoulder is set back more consistently. With all the brass being the same hardness helps. When sizing work hardened brass I get twice the spread requiring me to reset the sizing die every run. Which I do not like doing event though all I need to do is adj the shim pack.

 

[rskent]

Use redding competition shell holders to better control bump.

I use them as well. They do simplify setup.

Using an RCBS lube pad, i dont think i get lube on the shoulder of 243 or 223?

Which begs the question, is a lube pad that doesn’t lube the shoulder or inside of the neck a good tool to use?

I found that if I anneal the brass prior to sizing the shoulder is set back more consistently.

Me too.

 

[Walkalong]

Which begs the question, is a lube pad that doesn’t lube the shoulder or inside of the neck a good tool to use?

Necks are easy and don't really need lube in many cases, but both RCBS and Redding make coated bushings that do not need lube. Does Hornady?

.22 Hornet with Redding bushings.


.308 Winchester with RCBS & Redding bushings.

 

[rskent]

I don’t know about Hornady's. But to get consistent results, my Forster’s sure do. Maybe I need to be looking at my setup.