question about bullet brands for new reloader.

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mmcb987

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I apologize if this has already been brought up on THR but I could not find any information on the subject.

I have been looking up a lot of load data, and for the most part, the data is very bullet brand specific.

This is kind of confusing to me. If brand x is 9mm 115 gr jhp wouldn't that weigh exactly the same as brand y @ 9mm 115gr jhp. The same mass coming out of the same crimp with the same OAL. What is the difference here? (excluding powder/primer types). Just trying to be safe.

I have not actually started reloading, but am planning to very soon. I have ordered a few manuals along with my equipment.
 
The difference might be minor but brand x and y jhp have a slightly thicker/thinner jacket and therefore the bullet length is changed slightly, which in turn will be affected by the twist rate in your barrel .... also brand x might be "pointier" than brand y and thus ballistic coefficients will change (one more hollowed out than the other)...boat tail vice a flat base spitzer for rifle bullets.... flat brass enclosed base vice exposed lead base pistol bullets. There are many things which can affect a bullet's performance and a box of 9mm 115gr jhp will contain bullets weighing 114.045gr and 115.083gr etc.
How precise do you want to be for what you're reloading for?
 
Welcome to the wonderful world of reloading...

The reason for the difference in data for the 9mm and 115gr bullets, is that there are significant differences in the length of bore bearing surface. Also, the 9mm has a very small case capacity (efficient), and operates at high pressures compared to other contemporary cartridges such as the .45acp and .38spl. It actually operates at similar pressures to the .357magnum.

Two counter examples are the Sierra 115gr JHP and the Sierra 115gr FMJ.

The JHP has a much longer bearing surface and when seated into the very short 9mm case occupies a greater volumn of the case. Such causes the pressures to be much higher than that with the same weight FMJ that has significantly more of the bullet outside the case. It dosen't have the void in the nose which moves the weight foward..... with less bullet in the case...

Such is also the case with the .38spl and a 148gr wadcutter bullet seated flush with the case neck. With a given powder charge, the wadcutter will have higher pressures than a similar weight Round Nose bullet seated in the usual manner.

Thats why there is different data for different bullets of the same weight. The design of the bullet makes the difference....
 
The typical differences in the weapon's chamber, leade, bore, rifling and barrel lenght will make a bigger difference in effect than any small differences between bullets. Use your book data as generic by bullet weight and powder type, observe normal precautions and all will be well.
 
Yes this is the reason that we (experienced reloaders) always caution any new reloader to start with a 10% reduction from max charge and work up for the combination of components selected. This will build in a safety margin because the exact identical loading/components/firearm are not used. I have been reloading since the early 70's myself and still do this every time I try something new or change lots of propellant--no exceptions! IMHO when you loose your respect of reloading dangers you will soon loose fingers or possibly much more.
 
I'm going to let everyone in on a secret.
The reason there is differing data in different books is that if they were all the same no one would ever buy more than one.
 
also you cant always start 10% under max, if you reload for any of the magnums with win 296 the manufacturers warn against going under 3% of max because you could get unsafe pressures
 
Every time I decide to load a certain weight and design projectile, I look in at least a half dozen places to get all the various loads they suggest for the powder I am using. Now, with the internet, not only do I have about six references printed and bound at my bench, I can also go online and find another ten or so sources to choose from!

I then figure which is about middle of the road between them all. If one book happens to really show a huge difference, I will write that off as not being correct or accurate and will NOT use that particular load -- especially if it is telling me I can put about 30% more powder in my new loads than all the other sources state as their maximum loads!

I have many times started a load at middle of the road (all sources combined - except for extremely way over-charged loads) and have never seen signs of excessive pressure. I am extremely careful to make sure my scale is totally accurate, and that I have it adjusted properly. I make a note of just how full the cases are with this load (e.g., case 2/3 full). I am not saying this is what everyone should do, it is just what I have done ON Occasion! Considering the fact that the load I am loading, in at least one place is considered the Low-end of the load!

Main thing:
Be Careful!
 
If brand x is 9mm 115 gr jhp wouldn't that weigh exactly the same as brand y @ 9mm 115gr jhp. The same mass coming out of the same crimp with the same OAL. What is the difference here?
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Reloading isn't an exact science. When presented with a choice, always follow the bullet manufacturer's recommended load data. Even then variables will exist. That's the reason for starting loads.
 
The reason why data is bullet specific is due to the following:

Bullet Shape- some bullets are longer than others and take up more room in the case at a given OAL. You sometimes cannot increase OAL to compensate for the profile because the resulting round will not chamber. The shape of the bullet dictates how far from the rifling it sits at a given OAL. Hornady XTP, for example, have to be seated shorter due to their abrupt Truncated Cone nose.

Firearm Chamber- some pistols have shorter freebores (areas without rifling) and necessitate short OALs. Other firearms have long freebores and will accept any OAL that fits in the magazine. In most cases, you cannot load a Truncated Cone bullet to magazine length. But you can load tangent ogjive bullets, like those offered by Winchester, to any OAL you want.

Firearm Bore- most load data is developed in SAAMI spec test barrels, not actual pistols. These test barrels are made to minimum specs meaning the bore is tight (.355"). Actual pistols are quite a bit looser. My Sigs and Berettas, for examples, have .357" bores.

Legal- A bullet manufacturer cannot afford to state their data is universal. This would lead to legal problems if and when some yahoo blew up his gun. Making the data specific gives them a legal safety cushion: "Oh, you did not follow our data to the letter, therefore you are liable for your error..."

So, as you can see, mass is only one factor. You also have to consider the ratio of air to powder under that mass and how that totality interacts with the geometry of the firearm chamber (which varies from gun to gun).
 
Unless the bullets are the exact same shape (including the size of any hollow point) they are very likely to have differences in bearing area between the bullet and bore.

Even FMJs from different manufacturers can have enough shape difference to affect bearing area.

Add to that jacket thickness and hardness and the odds of two manufacturers having completely identical bullets is pretty small.

If you are not near a maximum load it is unlikely to be an issue, but if you take a maximum load with vendor X's 12- gr super expanding hollow point iit could well be over with vendors Y's bullet.

Buying large batches of a bullet you intend to use frequently (and large powder and primer batches) reduces time working up new loads every time you change something.

They are not as easily available now, but I still have factory cartons of bullets (2,000 to 3000 per carton) and 8 pound jugs of powder (purchased as a 32 pound carton) along with primers in batches of 10,000.

The load is about 7 years old, but I know I can load a few thousand rounds and get the same performance I have been getting for the past 7 years.

Usually all I have to do is dial up the micrometer head on the Uniflow, check the throw, and start loading.
 
Thanks for the replies everyone. The reason I asked was that I couldn't find any data on the RMR bullets that I ordered. I hear they make a good product and they seemed to be the cheapest that I could find in stock.
 
"I couldn't find any data on the RMR bullets that I ordered"

There are quite a few bullet makers we couldn't use if we had to have different loading data for all of 'em. Fortunatly, that's not necessary.
 
ranger335v said:
The typical differences in the weapon's chamber, leade, bore, rifling and barrel lenght will make a bigger difference in effect than any small differences between bullets. Use your book data as generic by bullet weight and powder type, observe normal precautions and all will be well.
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+
OAL of the cartridge which makes the most difference.

crestoncowboy said:
also you cant always start 10% under max, if you reload for any of the magnums with win 296 the manufacturers warn against going under 3% of max because you could get unsafe pressures
Click to expand...
Unsafe pressure meaning not enough to get the bullet out of the barrel. This could be dangerous because the second shoot would have a barrel obstruction.
 
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