Reloading  firearm cartridges: part 5

Reloading firearm cartridges: part 5

by using Tom Gaylord
Writing as B.B. Pelletier

half 1
part 2
half 3
half four

This document covers:

  • Reloading rimfire cartridges
  • good velocity for lead bullets
  • Strip out?
  • Case education
  • CUP?
  • Transducers
  • So what?
  • Brass movement
  • 5.fifty six mm brass
  • Trimming situations
  • abstract

there is loads of hobby during this sequence. I’m stretching it out over time because it deals with firearms, but it surely’s helpful for everyone to bear in mind in an effort to improved have in mind airguns.

Reloading rimfire cartridges

Reader Yogi requested about reloading rimfire cartridges. And he was justified in doing so, for the first firearm cartridges in any caliber have been either rimfire or needlefire — a kind of ignition I don’t want to get into in this sequence. Centerfire cartridges — the type we reload these days — got here a bit later on this planet of self-contained cartridges.

in reality, Yogi, you now not most effective can reload rimfire cartridges — there are precise kits to help you do it! because I had no idea any of this was feasible, I’m now not going to faux i do know what I’m speaking about. here is a brilliant article on reloading rimfire cartridges. And here is the vicinity the place the elements and tools are bought.

That noted, would you want to reload rimfires? It takes lots of time to do every thing that has to be done to reload a rimfire cartridge. except you are huddled in the ruins of a post-apocalyptic protect and fending in your existence I’m going to bet most of you’ve got more desirable issues to do. read the article and also you come to a decision.

precise speed for lead bullets

Reader 1st Blue asked me what the desirable pace for a lead bullet can be. Now a copper gas assess may also be put on the base of a lead bullet and it changes everything, so what I’m talking about right here is an all-lead bullet.

bullet gas check
A copper gas check has been swaged onto the bottom of the .308 bullet on the left. The .308 bullet on the appropriate is just lead.

I have shot gentle lead rifle bullets up over 1,300 f.p.s. with some success. I don’t like going that speedy, although, as a result of staying around 1,200 f.p.s. or less is nearly always extra correct. but he requested and that is my adventure.

Some reloaders trust that bullets need to be forged very hard to go their excellent speed. They communicate of Brinell hardnesses of 28-30 for their bullets and a few go better than that. My forged bullets are tender — in the Brinell eight-12 latitude. I do know that the harder the bullet the greater lead it’ll deposit within the barrel. tender bullets shoot a lot cleaner — but their top speed is probably within the 1,300s, the place some challenging bullet shooters are claiming up to 2,000 f.p.s. Put a fuel determine on the bottom and the suitable pace goes up over 2,300 f.p.s.

Strip out?

Many shooters together with 1st Blue are involved that lead bullets will “strip out” of the rifling at excessive velocity. I actually have by no means considered that or even heard of it occurring. as long as the bullet is one-thousandth of an inch over groove diameter, it should do neatly at any speed up to its max. I talked about bore diameter in an prior document and somebody brought my consideration to it. I’m speaking about measuring the diameter of the bore across the rifling grooves.

I have heard that tumbler-difficult bullets (Brinells of over 30) will once in a while shatter from the force of the gunpowder exploding at the back of them. I even have never considered that however again, I don’t harden bullets that challenging. I do be aware of that soft lead bullets don’t do that.

Case instruction

Some cartridges are low preservation and require little past cleansing and possibly resizing earlier than reloading. Straight-wall cases are among folks that are handy. that you may just reload a .38 particular case or a .forty five ACP case for a very long time earlier than they start to fail. So the form of the case is one massive a part of even if it is going to final a long time or no longer.

drive is the different huge explanation for case failure, and it is even more influential than the form of the case. Load a .38 special as much as +P+ pressures (over 22,500 copper devices of pressure — CUP) and the necks will start cracking after a couple of reloads. Discard the case if you note that. if you load the .38 special at or below 15,000 CUP you may get 20 reloads from it. I have a .32-40 rifle case that’s been reloaded about 100 instances and is still going robust, however I doubt my hundreds for that cartridge ever went above 10,000 CUP. truly they are so low that the lead unit of pressure or LUP can be used to specific them.

CUP?

once we get into the drive degrees of firearm cartridges we frequently don’t check with pressure as pounds per rectangular inch — even though it nevertheless is. We refer to copper units of pressure — which is the force that crushes a copper crusher gauge it truly is held in a verify fixture when the cartridge is fired. It isn’t fallacious to express pressure as psi, but CUP and LUP are the more usual skill of expression when talking about inner ballistics. When the drive is under 15,000 psi, the LUP is used.

Transducers

nowadays electronic transducers are used in its place of copper or lead crusher gauges. they are sooner and more cost-effective to make use of and cause fewer mistakes because cautious dimension of the crusher gauge is not any longer required.

So what?

right here is so what. Shoot that .forty four Magnum with loads that strengthen about 20,000 CUP and get 10-12 reloads per case. Bump the power up to 36,000 CUP and the case longevity drops to 3-four reloads. Drop it back to fifteen,000 CUP and get 25-30 reloads from each case.

k, all of that discussion become about straight-walled circumstances — apart from the .32-40. What about bottleneck cartridges? Let’s delivery with a common one — the .223 Remington this is shot in the AR-15. It customarily generates around 55,000 CUP/psi if you load it with standard looking masses. which you could go a bit larger, however no longer too a good deal.

Brass circulation

At this drive degree the brass the case is crafted from will move forward below force. It’s referred to as flow as a result of it is what happens. on the high drive the brass will flatten against the walls of the chamber and truly stream (move) forward. The size of the case will develop the greater instances the cartridge is fired. To offset that growth, we should trim the case again to a common size before reloading it once more. So we measure the size of each fired case and then trim all cases to one normal length before reloading starts off. In my journey, the .223 Remington case needs trimming after every three reloads. Trim it two times after which throw it away, because the place it flowed from is getting too thin.

5.fifty six mm brass

The armed forces version  of the .223 Remington cartridge is called the 5.fifty six mm cartridge. It is a similar measurement on the backyard, however it’s made from thicker brass. It will also be loaded into and fired from many rifles which are chambered for the .223 Rem. however — the 5.56 mm generates greater drive than the .223 Rem. It generates 58,000 CUP which doesn’t sound like a lot more — but the 5.56 mm cartridge chamber is 0.125-inches longer than a .223 Rem. chamber. Shoot a 5.56 mm cartridge in a .223 Rem. chamber and it generates 65,000 CUP, which is closing in on the proof pressure for the .223 Rem.! Case length and chamber length matters!

are you able to reload 5.56mm cartridges and shoot them in a rifle chambered for the .223 Rem.? sure — provided that you bear in mind that the thicker brass of the 5.fifty six case will dangle much less powder than the .223 Remington case when the bullet is seated to the equal depth. That’s no longer a foul factor because that thicker 5.fifty six mm case will generate more force with less powder. My guidance in case you wish to hit what you shoot at is do not mix .223 Remington and 5.fifty six mm cases collectively, and by no means load them with the identical quantity of gunpowder!

I keep my circumstances separated (the headstamp tells you what’s what) and that i increase loads for each class of case, retaining a pointy eye out for any signs of excessive force. they might be:

  • flattened primers
  • primers that circulation lower back into the firing pin hole
  • primer pockets that develop into loose (evidenced by using soot around them after firing)
  • cases that are bulged at their base (additionally a sign of excessive headspace)
  • cases that are split at their base
  • circumstances that are complicated to extract
  • situations whose heads are deformed (commonly they flow into the extractor cutout)

if you see ANY of those indications, stop shooting immediately and do not fireplace the the rest of these reloads.

Some circumstances actually stretch!

Of all the centerfire cartridge situations I have reloaded, the 6.5X55 Swedish Mauser case stretches probably the most. I had to trim them lower back after every firing and they begun splitting on the base after as few as three reloads. To prolong case life I reduced my loads except they generated around 20,000 CUP. You need to study the reloading manuals and interpolate to work out issues like that. after they had been loaded to that level I might get five or six reloadings earlier than the hazard signals appeared, and that they stopped wanting trimming after every firing.

The 6.5 Swede become this type of chore to video display that i stopped shooting them altogether. a person requested whether this stretching became due to extreme headspace, however took place on all 6 Swedes that I owned at one time or one other. It became simply too plenty to keep up with.

Trimming instances

I trim cartridges to length with an L.E. Wilson case trimmer. This tool dates back at least eighty years and nevertheless does brilliant work. Lee Precision also makes a a lot less costly case trimmer that i use for a pair calibers. where the Wilson depends on a bushing into which the case fits, the Lee has a relevant rod that limits the depth the slicing head can commute. The Wilson is universally adjustable for size, the Lee simplest trims to 1 typical length.

case trimmer
The Wilson case trimmer adjusts to a big range of cartridge case lengths. as soon as adjusted, each and every case that’s inserted into the bushing can be trimmed to the same length.

abstract

That’s about so far as I need to go with reloading, until there are particular issues a few of you wish to discuss. Reloading starts out standard and steadily turns into fairly complicated as you gain knowledge of more and more. As I mentioned in the starting, people that reload will also be shooting whereas others lament the lack of industrial ammunition. Plus, it’s fun!