Basic Reloading Question

For low power pistol rounds, primers don't matter a whit. Powder max listings should not be exceeded. Jacketed or plated bullets can be loaded the same as long as they are the same weight. Cast bullets are a different deal and should be loaded using data for them.

Welcome to the disease!

My experience is that any time ANY component deviates from the "recipe" for lack of a better term, it's time to back your loads off and work your way up.

Now, with bullets, specifically, there is a very good reason for doing this, especially between different TYPES of bullets (like with your question of FMJ vs. JHP). Remember, you're loading these cartridges to a fixed over all length, correct? Now, if they're both 180 grains, the FMJ bullet could actually be a little bit shorter than a JHP bullet. This is because that material they scooped out of the nose of the bullet has to go somewhere if they both weigh 180 grains, correct? Now if you're going from a FMJ bullet to a JHP bullet, your COL is gonna be the same, but your cartridge volume isn't. Longer bullet, more of it inside the case, less case volume, DRASTIC increase in pressure.

This could lead to what is affectionately know as a kB! (for the non-acronym savvy, that stands for kaBOOM!) :banghead:

This is known to be a very bad thing. It's hard on your hardware (your gun) and your software (the soft fleshy bits of you holding onto said hardware).

If you can't find a load that uses the specific bullet you want to use, I would suggest back up to the minimal amount of powder for that specific cartridge/powder/primer combo and slowly work your way up until you achieve similar performance to the previous load (yes, that means a lot of time with Mr. Chronograph).

Plated bullets use the same data as lead. This according to Ranier's website.

We, at Rainier Ballistics, recommend using lead bullet load data when loading our bullets. There is no need for adjustment when using lead bullet load data. Our bullets are jacketed using an electroplating process and are softer than traditionally jacketed bullets; hence the recommendation to use lead bullet load data. If you only have access to traditionally jacketed load data, we recommend reducing maximum charge by 10%. A roll or taper crimp may be used with our bullets; do not over crimp.

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All bullets of the same caliber and weight are not created equal.

You MUST pay attention to seating depth. Not just for feeding reliability but for intrusion into powder space. Two bullets of the same diameter and weight might sit in the case differently.
The smaller the combustion chamber the higher the pressure potential.
The higher prerssure rounds, such as the .40S&W, are even more succeptable to this.

This is why loading manuals are specific as to which bullets they state as tested.

Now, with bullets, specifically, there is a very good reason for doing this, especially between different TYPES of bullets (like with your question of FMJ vs. JHP). Remember, you're loading these cartridges to a fixed over all length, correct? Now, if they're both 180 grains, the FMJ bullet could actually be a little bit shorter than a JHP bullet. This is because that material they scooped out of the nose of the bullet has to go somewhere if they both weigh 180 grains, correct? Now if you're going from a FMJ bullet to a JHP bullet, your COL is gonna be the same, but your cartridge volume isn't. Longer bullet, more of it inside the case, less case volume, DRASTIC increase in pressure

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AmbulanceDriver, Are you saying that a change in seating depth will cause a DRASTIC increase in pressure? If I understand your post correctly, reducing case volume will increase pressure. If I have a load that shoots well and is well with in the limits of my firearm and I seat the bullet deeper I have now just created a "DRASTIC" increase in pressure? Please explain.

I would Call or write the Powder manufacturer, They may have a update on JHP bullets or at least some advice. Also you can check with the bullet Manufacturer’s manual… They have a load for that powder.

If you change any component, reduce your load and work up. If I were changing the type of bullet (JHP vs. FMJ) I would start at the Minimum load and work up, VERY carefully… The Shape of a JHP & FMJ is different and the seating depth will be different so the bullet doesn’t touch the lands.

The only time I have heard of a drastic increase in pressure from deep seating a bullet is where an autoloader's action shoved the bullet back into the case because of a poorly crimped round...then you do have a problem. Varying seating depth in a pistol or revolver round will have little effect on pressure within reason. YMMV

Simple physics here people

Varying seating depth in a pistol or revolver round will have little effect on pressure within reason.

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That's a very dangerous generalization.

Depending on the powder being used, and where on the richter scale the load stands, a small increase in seating depth CAN (i.e. has the possibility to) cause a significant increase in pressure.

For instance check out the difference in velocities between a Lyman 358359 148gr full wadcutter seated flush in .38 special and .357 cases and a Lyman 358385 150 gr lead round nose seated normally in identical cases. The WC has a much smaller powder chamber than the LRN.
Using the same powder charges velocities with the LRN were about 75-100fps less. I proved this with a chronograph 20 years ago.
Any idea the pressure difference it takes to create a 100fps increase in a .38 special?
Think it might be noticable?

Another thing to muddle the water when comparing load data is the barrel length used to get the numbers they are posting. I wish all the load manuals would at least use a standardized barrel length for each caliber.

Also I don't think a bullet cares how OAL changes, shortened by press/cycling or lengthened by recoil, its going to react to the change.

peace.
unloaded

Case volume

Any time you change any components you should start out using the lightest load suggested in the manuals. Seating depth CAN change your pressure CUPS by a lot in some cases as can using too little powder in a case. Not only can changing the seating depth change your pressures but believe it or not, different casing have different volume levels. Most casing of differnent manufacture have different case volumes. On the outside they look the same, but inside that's a different story. Although not drastic in most situations, there is a difference. Serious reloaders that shoot matches, will separate their brass according to manufactures. UMC, Winchester, PMC, Federal, etc. Take different cases from different manufactures and fill the case with salt or sugar, then weigh that particular volume against other casings from different makers, you'll see what I mean.

case volume and COL

Is this drastic increase in pressure something that occurs in both rifle and pistol or is this something that is specific to handguns?

Thanks

Rifle Pistol

Any center fire rifle or pistol casing.

I'm really going to stir things up here ! Even changing loads in to another firearm can affect it's pressure ! Rule of thumb if you change anything from what you've been using ! Go straight back to Min loads ! As firearms are mass produced there is a variation in chamber size (even a custom firearm is going to be different ) I have to change Barrels a couple of times a year in my Working Rifles & each time it's back to the drawing board to work up my loads again & Full lenght resize my cases ! Reloading gets some bad reviews as being unsafe ! That's crap !
Look if you walk across a busy street into on comming traffic ! Ya Toast Right? Reloading is the same ! You just have to pay attention to what your doing & if in doubt,just go back to the min recomened load & work it up slowly a little at a time until you find a load that works in that Fire arm !

Dave

Bullet seating depth can make a great difference.

One way to demonstrate this is as follows:

45 ACP, 200 grain bullet, 6.6 grains Unique for 898 fps, 16,200 CUP
45 Colt, 200 grain bullet, 9.0 grains Unique for 883 fps, 14,400 CUP

Note that this is a situation where the bullet diameter, bullet weight, and powder are identical. Velocity is darn close, but powder weight and pressure are vastly different. Why? Mainly due to the fact that the cartridge volume is vastly different, giving lower pressure with higher powder charge in the .45 Colt. The .45 ACP, having smaller case volume, generates greater pressure.

Seating a bullet deeper than decommended, while probably not as drastic as this example, will increase pressure. If you are already on the "bleeding edge" then you might just go over the edge. As a result, always back off and work up if you deviate from the prescribed recipe.

(Edited to add: The loads listed in this post are considered maximum in the manual from which I took them, don't use these as starting loads. I don't think anyone will mistake my post for a reloading manual, but you never know, thus this disclaimer.)

I guess that the "drastic" pressure changes I refer to are primarily with short, large diameter rounds (such as .45 acp) which experience marked changes in case volume, or with rounds that are already at the high pressure end of things (such as .40 S&W or 10mm). These changes are much greater than with, for example, a large rifle cartridge when comparing strictly the change in volume. I really didn't want to fiddle with the math, but here we go. Let's assume a nominal diameter of .45 inch for the .45 acp. And let's say that we have a internal case length (from base of bullet to bottom of inside of case) of .60 inch (This is an approximation, but it seems to be pretty close). So then, pi(r^2) gives us the area of the base of the bullet, in this case 0.159 square inches. Multiply that by our internal length, and we get .095 cubic inches. Now, if we use a bullet that is 5/100ths of an inch longer, or seat a bullet 5/100ths of an inch deeper, we instead get a volume of .087 cubic inches. This is a reduction in case volume of over 8 percent. Now, .45 acp, being a relatively low pressure round, should be somewhat forgiving with that. .40 S&W on the other hand, I don't know. It may survive, but you are probably going to be severely battering your gun.

Necked rifle cases won't see such a marked reduction in case volume, since the area at the base of the bullet is so much smaller than the diameter of the case, and since there is much more volume, relatively speaking, to work with. However, being on the high end of the pressure curve, I would also be very cautious when changing any component, and keep close watch for pressure signs.

The burn rate of smokeless varies dramatically with a change in pressure/temperature. The more smokeless is confined, the faster it burns. It seems that "faster" powders increase exponentially more quickly than slower powders, therefore slower powders are somewhat more forgiving. This, and the fact that you can see a double charge are the reasons I use slower powders.

I had some .45 acp pistol rounds that were loaded too deep. You could tell the difference just shooting them by hand.

When I was first starting handloading 30+ years ago with a Lee hand kit, I was making some 22-250 rounds for another guy. I knew virtually nothing about handloading but it didn't stop me. I was using 55 grain bullets. I seated mine to a little off the lands and they were fine. He wanted his seated the same depth as his factory rounds (considerably deeper). After one shot, he had to use a mallet to knock open the bolt.

I guess that the "drastic" pressure changes I refer to are primarily with short, large diameter rounds (such as .45 acp) which experience marked changes in case volume, or with rounds that are already at the high pressure end of things (such as .40 S&W or 10mm).

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The same phenomenon seems to occur with smaller diameters too.


Using the same 115gr .355" bullet & CCI 500 primers

Bullseye Powder
4.8 gr = 1184 fps @ 31,700 CUP in 4" 9mm Luger
5.0 gr = 1084 fps @ 19,100 CUP in 5" .38 Super

Unique Powder
5.8 gr = 1233 fps @ 30,700 CUP in 4" 9mm Luger
5.4 gr = 1039 fps @ 19,900 CUP in 5" .38 Super

W231 powder
4.9 gr = 1253 fps @ 32,100 CUP in 4" 9mm Luger
5.1 gr = 1026 fps @ 20,100 CUP in 5" .38 Super

700X Powder
4.5 gr = 1171 fps @ 31,700 CUP in 4" 9mm Luger
4.4 gr = 1032 fps @ 20,200 CUP in 5" .38 Super

HS-6 Powder
7.2 gr = 1193 fps @ 30,400 CUP in 4" 9mm Luger
7.5 gr = 1114 fps @ 20,500 CUP in 5" .38 Super

OR

Using the same 158 gr .358" LSWC

W231 Powder
2.5 gr = 727 fps @ 12,400 CUP in a 4" .38 S&W
3.5 gr = 675 fps @ 9,600 CUP in a 4" .38 Special

OR

Using the same 77 gr RNL bullet and Remington 1½ Primers fired from the same S&W 4" Model 31 revolver (sorry no pressure info available)
*same bullet sized to .309" fired from a 3" Mauser HSc - .32 acp although slightly longer in length usually has a lower water capacity than .32 S&W.


Bullseye Powder
1.5 gr = 578 fps in a .32 S&W case
1.5 gr = 513 fps in a .32 S&W Long case
1.5 gr = 685 fps in a .32 ACP case*

Unique Powder
2.5 gr = 743 fps in a .32 S&W case
2.5 gr = 608 fps in a .32 S&W Long case
2.6 gr = 860 fps in a .32 ACP case*

Red Dot Powder
1.9 = 763 fps in a .32 S&W case
1.8 = 588 fps in a .32 S&W Long case


Green Dot Powder
2.0 gr = 723 fps in a .32 S&W case
1.9 gr = 563 fps in a .32 S&W Long case


700X Powder
1.8 gr = 758 fps in a .32 S&W case
1.8 gr = 598 fps in a .32 S&W Long case
1.9 gr = 895 fps in a .32 ACP case*


So it seems the only real difference in each set of comparison cartridges is the length of the case. That means that powder chamber volume is the deciding factor.

Notice how in EVERY instance the smaller case shows a faster velocity and (where measured) corresponding higher pressure with the same or LESS powder than the longer/larger case.

Starting loads for jacketed can be used as a starting point for developing data for lead bullets. Lead has much lower resistence thus less pressure. Reduce the starting load by about 2-5 percent and work from there. DO NOT REDUCE POWDERS SUCH AS WIN 296 and H 110!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Starting loads for jacketed can be used as a starting point for developing data for lead bullets. Lead has much lower resistence thus less pressure.

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Not sure that you can consider this to be true in all instances. For example there are jacketed and lead bullets of the same weight where the bearing surface of the lead bullet is much greater than that of the FMJ. This would increase resistance as well as pressure.

The key words there were "Starting Loads".

Even when using heat treated linotype, lead bullet offers much less resistance than jacketed bullets. So any safe starting load with a jacketed bullet should be safe with lead. IF you pay attention to your seating depth.

Starting loads for jacketed can be used as a starting point for developing data for lead bullets. Lead has much lower resistence thus less pressure.

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But the factory says:

We, at Rainier Ballistics, recommend using lead bullet load data when loading our bullets. There is no need for adjustment when using lead bullet load data. Our bullets are jacketed using an electroplating process and are softer than traditionally jacketed bullets; hence the recommendation to use lead bullet load data. If you only have access to traditionally jacketed load data, we recommend reducing maximum charge by 10%. A roll or taper crimp may be used with our bullets; do not over crimp.

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Ed (E. C.) Harris says lead bullets develop higher pressures than jacketed bullets because they obturate better. I have reluctantly accepted his conclusion, based on my own experiments. Do not assume lead bullets will give lower pressure.

In my experience all components matter. Bullets matter a lot. Most books have very different loads for FMJ and JHP. If you are in doubt call the bullet manufacture and ask a pro… If you change primers step the charge down (not below Minimum) and work up… same with brass, seating depth… If you change bullet styles call the manufacturer.

Ed (E. C.) Harris says lead bullets develop higher pressures than jacketed bullets because they obturate better.

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While it's true that lead bullets obturate better, lead has a much lower friction coefficient than a similar size/shape jacketed bullet.

This is shown to be true because it's almost impossible to wear out a bore by shooting lead bullets.