[ExMachina]

Would anybody care to share some of the general reloading principles they have found to be particularly helpful? I know that some very good information already exists here (and elsewhere) on equipment and techniques. However, being a neophyte to reloading, I would love to see some *general* information I can apply when trying to decide how to err on the side of safety, efficiency, and accuracy when developing a load.

To start things off, I’ll offer several points which are unclear to me :confused: :

1) Cast bullets vs equal weight jacketed bullets—how do they differ in the chamber pressures they generate. How do moly coating or copper plating figure in?

2) For an identical loading (rifled portion of barrel being of equal length), is there any meaningful difference in pressure curves between autoloaders and revolvers?

3) What are signs to look for to indicate that you are approaching the limits of a gun’s design?

4) I've heard of using fillers for small ammounts of powder. How does powder *volume* figure in when compaired against case volume--can you ever have too little/too much?

5) How does primer choice affect pressure velocity for an otherwise identical load?--is hotter always better?

Thanks for any help.

-Dave

[Gary H]

Do your research and then save your money. Buy the equipment that you want. Quality tools will keep the regrets down later on. Should have bought the Spolar....

[larryw]

I'll take a swing at a couple.

1: Jacketed bullets generally require more powder than lead to reach the same velocity because of the force required to engage the rifling and drive the harder bullet down the barrel. Plated bullets, IMO, are to be loaded like lead as the plating is thin and does not measurably change the hardness of the bullet. Moly is a lubricant, easing the bullet's path down the bore, treat accordingly. But remember, there are no absolutes in reloading (outside the fact that there are no absolutes in reloading).

2: I have no idea, interesting question.

3: You know you're approaching the limit of your gun when it breaks or wears out prematurely, so don't do it. Look for signs that you're approaching the limit of the load by examining the cases, primers, extraction, etc. This is discussed in detail in Rodney James' book, The ABCs of Reloading (Amazon carries it if you can't find it locally). He also discusses how he blew off a hand.

4: Fillers like dacron are used to keep the powder charge in proximity to the primer for consistent ignition. These don't measurably change the case volume as they're mostly fluff and burn off as the charge ignites. One example of many why you'd use a filler: suppose you have a small powder charge and you've had the gun holstered. When you draw, the powder may be against the bullet and the primer flame has to jump the gap to ignite the powder which can lead to inconsistent ignition. I don't know the dynamics of case volume to powder charge because that is the domain of the experts who work up the load data in the manuals for a living.

5: Primers can effect ignition and using Magnum primers in a standard load can and will effect pressure. When you change any component in a load, safety dictates you proceed with caution. This applies to primers.

[dodgestdshift]

Ex:

1) There is more friction using a jacketed bullet rather than a cast bullet. All things being equal (highly unlikely) the jacketed bullet of the same weight behind the same charge of the same powder will have higher pressure.

2) You have to be careful with this one. The barrel length of the gun is measured differently in a revolver than in a semi-auto. The revolver barrel length is measured from the muzzle to the beginning of the forcing cone, the semi is measured from the muzzle to the base of the chamber. To compare the pressures and overall performance of equal length barrels you have to take this into account and also the cylindar gap in the revolver. To sum up comparing a 4 in. revolver to a 4 in. semi, the revolver has a longer barrell but also has a cylindar gap. Whether the differences cancel or one gives better performance is out of my league.

3) If you stay within manufacturer's recommended limits you will never find out what happens when you get near the "limits of the gun design" and that's a good thing.

4) I am not sure I understand completely the problem but generally "all things being equal" the less case volume the higher the pressure. This can be noticed with thicker brass, you have to drop the powder charge to keep pressures the same. Too much volume can cause misfires and inaccuracy due to the powder's non consistant ignition. Also be aware that some have claimed that small amounts of slow burning powders have "detonated" and had the same effects as a gross overcharge. As far as I know this is controversial, but safety first, stay within manufacturers recommendations.

5) Hotter primers (magnums) are usually used with large volume cases with slow burning powder to get more consistant ignition. They also have uses in very cold climates. In other case they could raise pressures. Under normal circumstances loading manuals recommend whether to use magnums or regular powders.

Hope this helps.

[E357]

Question 2) As pointed out, the bullet travels maybe 1.5 inches more out of a revolver that has the same length of barrel as a semi-auto. However, the revolver has that pesky cylinder gap that leaks pressure in some unknown amount. In my limited experience with the same cartridges and barrel lengths - 1911's vs 5 inch 625's the same loads chrono about the same with my 625's actually a tiny bit faster. But I've only chrono'd target type loads and my cylinder gaps are small.

Elliot

[ExMachina]

Thanks for all the input thus far. Yesterday I picked up a 4th edition Speer manual which has clarified several things regarding technique, but the theory info is still lacking. I've also ordered the ABC's of Reloading in the hopes that it will offer some insight.

Back to a couple of my original confusions...

1) Reloading manuals almost (always?) give cast bullets a LOWER maximum charge than jacketed? This would seem to imply that the lead load is achieving the limit pressure with less powder, right (which would mean that the jacketed bullet is sealing less efficiently perhaps?) So, a load that is designed for a lead bullet could then be safely loaded w/ a same-weight jacketed bullet, but the reverse (substituting lead for jacketed) is not necessarily safe--right?

2) The reason that I'm curious about this is that none of the reloading manuals I've looked at mention barrel/cylinder gap in the test guns. If their test gun had a b/c gap of say .008", it would seem to imply higher pressures in a gun w/ half that much of a gap.


Can anybody recommend a good book with info on the pressures generated in various firearms?

-Dave

[dodgestdshift]

ex:

1) There are several reasons why reloading manuals give lower charges for cast bullets among the reasons I can think of are:

a) Jacketed bullets can be shot faster because lead bullets driven fast (somewhere over 1100 fps) will begin to shread in the the barrel and lose accuracy fast as well as make for a nasty cleaning job.

b) Manuals will sometimes give a accuracy maximum load for lead bullets and not necessarily max pressure load.

Usually your statement is right that a lead load causes lower pressures than jacketed. I would not substitute a lead bullet for a jacketed bullet load unless it is mentioned in the manual as ok. There are many other factors to consider and you should leave that kind of activity to the people who write manuals. Stick to the loads in the manual, and you will be all right.

2) If you are asking if you can figure pressures in your gun by measuring your cylinder gap, I would not do that. There are many things that effect pressure including cylinder gap. If you are using your measurement of the gap to load "a little higher" don't do it.

The only way to get pressures on your gun is with highly sophisticated equipment which probably the average reloader doesn't have and will never have. There is a gizmo on the market that uses a strain guage to measure pressures, but I don't think it will work on a handgun.

As for pressures in various handguns, I have never heard of any such book. The pressures can vary between the same firearms with almost identical serial numbers. I suspect that the pressures vary in the different cylinders of a revolver. This is probably due to manufacturing tolerances.