Different weight 9mm

[Jeryray]

Been re-loading 115gr FMJ with 4.1 Bullseye. Worked out fine.
Noticed my dealer only had 124gr 9mm. Did not realize until I got home.

Would it make much difference in the load?

Any direction appreciated.

TIA

[Aguila Blanca]

Define "much."

It makes a difference. How much probably depends on the bullet construction and the powder used. In general, you need/want a bit less powder behind the 124-grain bullets. I would drop your load by at least 5 percent (or 10 percent if you really want to be safe) and work back up from there.

[higgite]

What does your reloading manual say?

[Tsquared]

Not knowing what type of bullet I pulled out my Speer manual. I rarely use the Speer as they treat all of their bullets the same except for the COAL. And it is data for their bullets.

Bullseye starting 3.9 966 fps Max 4.4 1059fps
Speer Manual for 124 grain 9mm bullets
9mm TMJ RN COAL 1.135
9mm UCSP COAL 1.120
9mm GDHP COAL 1.120

That said, I load RMR 124gr HMFNP with 3.9gr of Bullseye with a COAL of 1.125 and it is getting 1102fps in my Colt Govt. The RMR is a heavy plate bullet.

I have 4 manuals I draw info from plus the powder and bullet manufactures data if available.

[bigcountryeb]

You will want to use less powder. As to how much less, see your manual, start with a starting load, and work up from there so as to avoid a "boom." I personally only use 124 and 147 gr bullets in 9mm. I find the bullets are not much more expensive than the 115 gr bullets and use significantly less powder. I find accuracy is also better with these heavier bullets in my 9mm carbine but there isn't much difference in my pistols. I find the 147 gr. Bullets have a lighter recoil impulse than lighter bullets. If you shoot lead bullets I would suggest heavier bullets as the lower velocities you will get with heavier bullets should reduce leading.

[Don Fischer]

I tried 115gr bullet's in the beginning but didn't bother with a second box. Just didn't care for that light a bullet. In my carry gun I use 124gr JHP. I think I'd like a bullet that expands well. It should help limit penetration. Shooting through some one and getting some one behind bother's me. For practice I cast 124 gr bullet's. Also use them in my other 9mm I keep for around the house. I have though several time that just maybe the 147gr HP might be a better choice. But haven't tried them and know all things being equal, the extra weight will cause more penetration. Bad thing about this is it's all really no more than a guess. Until you actually shoot a human being, you really don't know what might happen. with luck, we'll never find out!

[kmw1954]

Jeryray, have been loading and shooting a large mix of both 115gr and 124gr from 2 different guns. My impression is this. If both are loaded to the near same velocities you will not see much difference in performance or the way they feel.

The difference will come with loading them though. The heavier bullet will use less powder and normally be made a bit longer. With the 2 powders I use I find a loading difference of about .5 gr between the 2. Also the 124gr are being seated out to 1.155" to 1.160" while the 115gr are seated 1.125" to 1.140".

So use them up, just restart your load workup. It should only take a few rounds to get back on track and then you'll also have that data for the next time. I find I buy my 9mm bullets by what's on sale at the time, 115gr or 124gr.

[hdwhit]

Jeryray wrote:
Would it make much difference in the load?

Considerable.

First, consult your reloading manual (if you don't have a manual, go get one, preferably one published by the people who make the bullets you are shooting).

Second, consult the powder manufacturer (http://alliantpowder.com/). You may need to contact their support people since they are emphasizing their new Sport Pistol in place of Bullseye for 9mm.

Third, proper load development begins with the Starting load (it's known as a Starting load for a reason) and if you're not given a Starting load, take the Maximum and back of 10%. Load and test rounds at the Starting load. Depending on the difference between the Starting and Maximum loads, increase subsequent loads by 0.1 or 0.2 grains until you find a load that 1) cycles the gun reliably and is accurate, or 2) begins to show pressure signs.

[hdwhit]

Don Fisher wrote:
I think I'd like a bullet that expands well.

The paradox everyone faces is that expansion of soft and hollow point bullets is closely correlated to velocity. The higher the velocity, the more likely it is to expand, but to get higher velocities the bullet has to be lighter (and all the things that entails).

... all things being equal, the extra weight will cause more penetration.

But all things are not going to be equal since the lighter bullet is generally going to have greater velocity.

And, human beings are not blocks of ballistic gel; they have bone, skin, muscle, various kinds of tissue and even empty spaces all of which can greatly impact the bullet's performance.

-----

Also, if you're going to carry reloads in an SD pistol, please be sure to read the articles on the subject in the legal forums on this and other firearms sites. There are potential problems particular to these of hand hand-loads in a self-defense situation that may make it wiser to carry factory loaded ammunition.

[T. O'Heir]

4.1 of Bullseye is a tick below minimum for a jacketed 115. Only .1 of a grain so it won't matter. However, when you change bullet weights you must work up the load for that weight. 4.1 of Bullseye is a near start load for a jacketed 124. 4.4 is max. 4.0 is the start load.
The 124 grain 'GDHP' data you see on Alliant's site will do nicely. You load according to the weight and cast or jacketed. Not the maker of the bullet.
"...the Speer..." Both Speer and Alliant are owned by the same holding company. (who also own Federal) Chances of them using different ballistics labs are decidedly slim.
"...a bullet that expands well..." Is not an FMJ.

[Unclenick]

Guys, let's not wander off into SD loads and other OT subject matter.


Jeyrey,

What Alliant lists with Bullseye is about 14% lower in a 124 grain bullet than in a 115 grain bullet. QuickLOAD gives exactly that difference for 115 and 124 FMJ's. So 3.5 grain for the heavier one should produce the same peak pressure as 4.1 grain behind the 115 grain FMJ. This assumes same COL, so the 115 is seated more shallowly in the case than the 124 is. MV from a 4" tube will be down about 75 fps.

[RC20]

Unclenick: but we have the most fascinating conversations going off track.

Jeyrey: I would get a manual, even if its an out of date Hornady 9 - 9mm is a picky round pressure wise (that and smaller rounds, it don't take much to get a large affect)

Normally I would then start at the low end and work up. If its FMJ, then Hornady will have an identical shaped round in their group. Their data is conservative as they will have a number of shapes and the loads are good for all of them.

I don't have my books available, not sure where that 4.1 falls in the scheme of things, Aliant list it as pretty mild for 115. I don't see the 124 grain load with just an FMJ.

[Jeffm004]

As a data point, I load 124 platted at 4.2 of Bullseye. Around 1075 fps, 4" barrel.

[RC20]

Good base reference.

[noylj]

I don't understand--the ONLY response is "refer to a manual."
There should be no guessing or assuming.
My own method is to check several manuals and start at the LOWEST start load.
For 115gn FMJ bullets and Bullseye, start loads range from 3.5-4.5gn and MAX loads range from 4.0-5.1gn. I would certainly NOT start at 4.0gn or higher.
For 124gn FMJ bullets and Bullseye, start load range from 3.2-4.2gn and MAX loads range from 4.3-4.9gn.
To me, this indicates that the mix of components can have a major effect on pressure and you should NEVER assume anything, particularly that one manual has "better" data. It also shows that the 124gn bullets "typically" uses about 0.3gn less powder.
So, 4.1gn Bullseye with 124gn FMJ is just below the lowest MAX load and just below the highest START load.
I wouldn't risk it and I would use the start load, where most of my manuals used a 3.3-3.5gn start load.

[kmw1954]

For 115gn FMJ bullets and Bullseye, start loads range from 3.5-4.5gn and MAX loads range from 4.0-5.1gn. I would certainly NOT start at 4.0gn or higher.
For 124gn FMJ bullets and Bullseye, start load range from 3.2-4.2gn and MAX loads range from 4.3-4.9gn.

I have to say those are some very wide variances. Over a full gr. difference between starting loads and also over a full gr. difference in Max loads. Sorry but that makes me nervous, One full gr. of Bullseye is a lot of powder. Where these all with the same bullet or were different brands used?

[noylj]

That is what you get from variances in components (bullets and powder mostly).
Since I have no idea how my mix of components matches ANY manual, I start at the lowest start load I can find.
When you have a start load recoil worse than factory ammo, you start to be a bit more cautious at assuming ANY manual has better data than the others.

[Nick_C_S]

Looks like this topic has been covered thoroughly.

I just want to add some perspective:

Jeryray, when moving from one bullet to another of significant weight difference (like in this case), it's best to just start your approach from scratch. Don't view the 124's charge weights relative to the 115's. They're two different things and have no relation to one-another.

Just do a restart. Gather 124 data and proceed with your work up with the usual caution. And read Unclenick's post

In more practical terms: You should be able to make some good consistent shooters with 124/Bullseye. That said, don't forget that you're dealing with a small case and a really spunky propellant. Small changes in charge weight can make for big changes in peak pressure. And the heavier the bullet, the more this is true. i.e. a 124 grain bullet will grant less forgiveness than a 115 grain bullet.

Load safe.