Lester,I have not heard of truing up the bolt face. The lugs, yes. Now on my rolling block it is a definite issue that has to be addressed. I do this by indexing my brass and align it when inserted into the chamber.

Brass is different than steel in that you can only soften (anneal) brass with heat, and quenching in water will stop the heat from migrating to the base of the shell but won't do anything else. No need to use ice water or even quench for that matter because it doesn't change the anneal once it gets to the right temp just pull the heat away and you're done. From what I've read annealing brass is a very specific temp and time. The hotter the flame the less time it takes to anneal, but it's very easy to over-anneal and that's where you get into trouble.


Suz

Suzanne wrote:

it's very easy to over-anneal and that's where you get into trouble.

I tried annealing once with a torch and drill to spin the case. I need more practice. I had a couple of cases where the shoulder collapsed during bullet seating and several that buldged out when loading a compressed load.

Oh,the primer pockets started being too loose shortly after, but not related, and I had to discard the cases. Thus, have not seen the value of trying to anneal again.

Lester,I have not heard of truing up the bolt face. The lugs, yes. Now on my rolling block it is a definite issue that has to be addressed. I do this by indexing my brass and align it when inserted into the chamber.

Lady's and gentlemen as far as reloading and firearm mechanics I will bow to most everyone of you as having far more knowledge about the subjects than I. Frankly, after all my research on the subject of cartridge to chamber clearances, bolt face and lug lapping, and a plethora of other sloppy areas I am surprised that we can hit the broad side of a barn let alone produce some of the groupings we do.

But, I am looking at everything from a die makers perspective, and there is a ---tload of slop in the chamber/cartridge interface, obviously it works, better sometimes than others.

The reason I commented regarding the alignment of the projectile to the cartridge, is that I agree wholeheartedly they should align as closely as we can possibly get them, but that in my simplistic thinking there were other issues of equal importance.

As I began pondering the other factors in the slop of the chamber/cartridge interface using my limited knowledge of rifle actions these are some of the questionable areas I have come up with. I don't think we ever have to agree entirely about this stuff and I truly enjoy reading all your comments so if I am off base please edify me, but I would prefer objective and not subjective enlightenment.

The first action I can imagine on ignition of the primer and the forward movement of the projectile is that the cartridge slams back into the face of the bolt. Therefore if the bolt face is not perpendicular to the center-line of the bore the cartridge will cock to whatever tolerance of clearance exists between the chamber and the cartridge and miss-align the projectile to the bore. As there is clearance between the ogee of the projectile and the rifle bore there is plenty of time for this to happen. Now, having said that I understand that the expansion of the cartridge (form fitting to chamber) may lessen the impact of an out of square bolt face but do not believe that it eliminates it. Because there is a good deal of tolerance in the wall thickness of the cartridge body, as I have read up to .003. That tolerance itself makes me question fire or form fittings benefits (I may be splitting hairs that have been split a couple times already, but as a die maker I have to look at the potential total stack up error).

If a cartridge has that much tolerance in its wall thickness then it will cool unevenly, slower in the thick sections than the thinner sections, then couple that to the cylindricity of the chamber and I question its total value. As far as I can see the only way to assure that we are getting the true value of fire fitting our cartridges is to index them ensuring that they go into the chamber the same way every time.

Now to reloading, what is the primary contact on your press. As I have said I am using Lee presses and so it is the face of the base of the cartridge, you know the part that I say slams into the face of the bolt, My reloading set up is all I know if yours is different I'd like to hear about it. My set up does not use the fire fitted outside diameter of the cartridge for anything as all I do is resize the neck. So add all the alignment issue of a press, the tolerances required to allow it to work and then the clearance and tolerance issue with the cartridge and chamber and as I said I am amazed we can hit anything more than a few inches away from the muzzle. I really think that projectile alignment to the cartridge is critical, but I also think the bolt face must be perpendicular to the center-line of the bore, and to truly benefit from fire fitted brass they must be indexed in such a way that they go into the chamber and into the reloading press the same way every time.

Lester, I will be the counter. The bolt face makes no difference. The thin brass side walls expand first grabbing the sides of the chamber wall.

Cut open a brass case and look how thick the internal structure of the case is. It is not going to bend and miss align when it goes into the die for resizing. There is so much slop in the base, the first interface with the die is the already fired and concentric case neck. The second is the case wall then the shoulder. The primary purpose of the base is to have a lip on it to extract the case out of the die.

Any modern bolt face is close enough. It doesn't matter compared to the other factors we are discussing. As you pointed out already the slop In the chamber all goes away on the first firing.

One note...Firing pin strikes the primer pushing the case forward. As the powder burns it slams the case head against the bolt face just before it expands enough to grip the chamber wall.

Totally agree Lester! and I have to say I never thought about the slop in the chamber. Why has no one devised an idea about how much the barrel is involved in straightening everything out? With the distance the bullet has to travel you would think that things could be pretty out of square on the cartridge end of the action and still come out in a straight line, because the barrel is the last thing the bullet reacts to. If you start the equation with the first action on the ammo (firing pin) and discount the last action on the bullet (barrel travel) then you've missed something. Take everything into account to come up with the final factor. How much does the barrel influence the final out come?




Suz

Here is a good read (with pics) from Hornady on the beginning of internal ballistics.

www.hornady.com/ballis...e/internal

Bushmaster wrote:

One note...Firing pin strikes the primer pushing the case forward.

True, bullet is now in alignment with the bore.

Bushmaster wrote:

As the powder burns it slams the case head against the bolt face just before it expands enough to grip the chamber wall.

Whether true or not, for every action there is a reaction. If the case is going aft against the bolt face, the bullet has already gone forward.

The thought that an "out of square" bolt face may have an effect on bullet alignment with the bore when fired is an interesting thought. However, I feel that any misalignment is minimal to the point of being moot as demonstrated by the fact that we do achieve excellent accuracy from our firearms.

I'm not a tradesman, nor do I have the knowledge or expertise of Lester (correct me if I'm wrong, but being anal about exact measurements is almost a prerequisite for being a toolmaker) or the mechanical knowledge (of parts alignment and movement) of Bushy or others here, but i think that there may well be self correcting fault actions at play as well. When fired, the bullet leaves the cartridge case at the angle the case is aligned. This bullet (which is base heavy) then moves forward to contact the rifling then continue on its journey down the barrel and onward to the target. I believe that it is this base heavy property that helps the bullet enter the rifling straight, or it straightens the bullet as it enters the rifling.

Suz added another necessary consideration, that of the barrel...add to that the harmonics of the barrel. (My head is starting to hurt.)

All very fascinating reading on the mechanical aspects of firearms and shooting, but unless you are tooled up to machine parts to extremely close tolerances, there is little we as shooters can do other than what we do now...load development to suit our particular firearm.

Lester, maybe you could measure the alignment of the bolt face to the chamber. Only way I can think that you could do this is by making a chamber cast using Cerrosafe and then check all measurements, including the bolt face/chamber alignment.

Vinnie to square up a bolt face you remove the barrel and use a tool that screws into the receiver threads. It holds a polishing disk that is square to the bolt face. You lap the bolt face with polishing compound to get it (square) at a right angle to the bore. You have to start out with a square receiver face, which is what a gunsmith can do for you on a lathe. I always did it to my Mauser builds along with lapping the bolt lugs which makes sure the lugs all contact equally. Personally I do it before I even shoot the gun, sort of truing up everything I can, then attaching a new barrel and seein what it does. If there's some sort of anomaly that makes it not shoot right, then I already know it's not the squareness of the action to the barrel, because once you get the barrel attached it's a pretty awful pain to have to remove it.

I've had good results doing these truing-up rituals, or I have good luck to start with, considering they are vintage veteran actions.


Suz

Thanks Suz...I thought that if you do a chamber cast against the bolt face you would be able to measure to see if there was a discrepancy. The method you describe would not measure for a discrepancy...it would correct one if it existed, but more importantly ensure everything was square.

Yes Vince I am a little anal about dimensions, fit, and alignment, well maybe not just a little. I hate woodworking it just won’t hold my dimensions. By God, if the hole is 2 inches then 1.9999 should go in and out of it all the time, damn wood. I say again I know that the vast majority of you have more knowledge about reloads and rifles than I, I am just conjecturing, and because of my paranoia on dimensions, fit, and alignment I think about this stuff all the time, used to spend all my time chasing women, but today I’m don’t do that for fear I might catch one.

Anyway to continue playing the devil’s advocate role I did a little calculation and found that if we have a base of .375” and a length of 2.5”. And, if the base is out of square to the side by .0001 that results in .031 degrees deviation in the squareness of the end opposite the base. That amounts to a variance of .00135” off centerline at the opposite end of the base. Or measured from the centerline .000675” per side. Hope I did the math right it’s been a long time, but if I am wrong I am sure somebody will correct me. Now as for fire fitting, a cartridge does not just grow diametrically when exposed to up to 60,000 PSI they grow in every direction to fill the available cavity, the only factors that can logically effect the amount of expansion is the amount of crimp on the projectile and the time between ignition and the projectiles contact with the bore. So the cartridge expands to some lesser or greater degree to fill the available cavity, and then retracts after the pressure is gone and further upon cooling, but to some degree or another it retains the shape of the cavity both diametrically and longitudinally. Add to this the unique characteristics of each individual cartridges wall thickness. Its physics, I didn’t make the rules.

Doesn’t sound like a lot, but now we have fire formed all the cases we are going to reload and they all have this squareness issue. So now I am going to reload and by gosh the base of my reloading die is out .0001, and the neck sizing die is off .0001 in the opposite direction and so on and so on. So during reloading I could be compounding the out of square. And, I am only talking about .0001”, what if it was, and most likely is more. And, now I put that cartridge back in my rifle but this time it goes in 180 degrees from its first time, what can I expect?

As I said before I am surprised that we can achieve the accuracies we do a 100, 200, or 500 yards down-line based on what we are working with.

Now I am not suggesting that we all need to send every one of our actions in for blueprinting, and I am not talking about loading a 40 round clip for an AK-47 to blast away at a heard of zombies. I am talking about sitting at a bench and seeing just how small we can make that damn pattern. So in all likelihood we are loading singles by hand and taking time between our shots.

I have read a lot about reloaders that get a real nice three shot group and the fourth is a flyer but the fifth is back in, then I’ve read about folks who have recovered their bullets only to find that the rifling patterns are much longer on one side of the bullet than the other which would mean that the projectile was yawing or creating a helical pattern at its nose in flight. And, that makes me think about the times where I’ve read about the projectile creating an oblong hole in the paper, meaning that it hit somewhat sideways.

So, in thinking about all these results and wanting to develop a dialog I brought the subject of the bolt face up. Again, I agree that our bullets should be as concentric as we can get them to the cartridge, and I was not arguing that point. I have no idea how square my bolt faces are, they are as square as they came and will stay that way, but there are some things that I do that I believe help with the accuracy (and more importantly the repeatability) of my reloads, can’t prove it cause I can’t shoot that much anymore, and my grandson Douglas will be shooting my reloads after I’m a memory. Of course that’s barring a heard of zombies coming up over the hill anytime soon.

Anyway, when I sit at the bench and as best I can when hunting I try to make sure that my cartridge goes into the chamber in the same orientation every time, and when I was reloading I made sure that it went in the press the same way every time. Additionally, when changing out my dies I try to make sure they are in the same orientation every time. Is all that significant, I don’t know, and I would love it if someone who still shoots a lot would test my theory.

We will never reach perfection, all we can hope to achieve is a very high degree of repeatability, but I believe we can only achieve that if we do it the same way every time. Basically, I do not care if my bullet comes out of my barrel at some small angle, I only care that it comes out at that angle every time I shoot.