I purchased a new Shield Plus and decided to load up
Some new rounds. All I could find was 115 grain Hornady
Xtp bullets. I found some load data starting at 4.2 grains and all the way
To 6.1 grains starting charges. I’m a little nervous with such a
spread in starting charges. Anyone have a good formula that I can start with?

That's one reason you should consult several paper load data sources and at least one of those should be a Hornady book if you're going to use Hornady bullets. Many good powders and what works for one may not be the best for you. Enjoy load development. Effort will pay off.

Unique wouldn't be my first choice but it's a good 9mm powder and will work without problem so use what you have but also consider others.

FWIW, buy and Study at least 3 book type loading manuals.

What manuals do you have? Hornady, RCBS, Sierra, Lyman can all be trusted. Don't worry about the specific bullet, use 115 grain data from anywhere. for any bulletJust be sure you are looking at standard pressure or +P loads

This doesn't answer your question directly, but my standard 9mm load with 124 gr. bullets is 6.1 gr./Unique. I had to go that high to get my P-1/P-38 to function! As long as you stay below 6.0 with the 115 grain there will be no issue. For a starting load reduce this by 10%.

For some reason Alliant doesn't show Unique for 9mm in their on-line reloading center.

rockquarry gives good advice, buy as many different loading manuals as you can afford so you can cross-reference if you have concerns like this. Buy a chronograph too, really!

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Gunsmithing since 1961

I’ve starting using CFE Pistol for just about everything and really like it.

Hornady 10th says 4.3 - 5.4 grains. 1.075" col.

Attached Images

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Follow the Manual

It's not directly relevant, but 4.5 gr Unique under 125 gr Speer LRN was the unmatched accuracy king in my issue 5906 back in the day. I could ring (but not topple) 200 meter IMSHA rams with boring regularity.

I have learned that no matter what manual I buy, there will be a new edition within two weeks.

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"Don't Give Up the Ship"

... of your present formula. I used Unique and Accurate#7 to get some pretty hot loads experimenting with heavy (147 gr to 160 gr) 9mm bullets. I didn't get a good defense load because of poor expansion of available bullets in that weight even with a modified hollow point, but I sure got some good shooting, ACCURATE loads with heavier bullets.

PS: Loading data for the heavy bullets was SCARCE!

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"He was kinda funny lookin'"

Hornady's data for the bullet starts at 4.3 with a max of 5.4

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it just needs more voltage

I'm going to argue with you just a little bit on this.
Bullet construction starts to matter in this cartridge as it's capacity is fairly small.
to be of the same weight, a hollow point design must take up the case volume displaced by the cavity. Thus, a HP tends to be in a lower range of charges than it's solid counterpart.
Lead vs jacketed also shows up in the data
The safest bet is to seek data for the exact bullet you are using. If that is unavailable, Use the data from the bullet most similar to the one you're using.
In this case, it's the 115g XTP .... probably the most prolific hollow point on the market with an abundance of data behind it across several component combinations.
We'll rarely have it as good as this particular case.

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it just needs more voltage

The 9mm has a small case, bullet seating depth along with bullet design has a lot to do with the pressure in such a small case. both have a factor in case volume, powder charge is only one part of the big picture.
not all 115 grain bullets are the same

The XTP’s can have a longer bearing area (greater friction) than generic 115g data.

I’d encourage you to pick up the Lyman Third Edition Pistol and Revolver Handbook. Inexpensive and lots of data. They show a range for Unique of 4.4g to 5.8g max specifically for the 115g XTP.

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Uvidíme se později, aligátore.

I use Unique with my 9mm loads for factory or +P loads, if needed.
Some of the top loads with certain style bullets are a "Compressed load"
so you do have to know what you are doing in these high pressure, areas.

I try to save my Unique when loading light, target loads and use a medium fast, burning powder, in the 231 range, or faster.

Have fun.

...with compressed loads in 9mm? Just seating the bullet I always bulge the case.

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"He was kinda funny lookin'"

As rockquarry mentioned; Hornady bullets-Hornady data. I have found the safest/best data is from the bullet's manufacturer...

Using a 115 or 124gr coated lead bullet, my standard load was 4.5gr of Unique. Fairly soft but for plinking with cheap lead bullets, it was perfect. Then my son started playing around with building Glock clones---evil ghost guns. 4.5gr would not reliably work the slide. We bumped it up to 4.8gr and it got much better but still not 100% function rate. So we ended up at an even 5gr. I use the same 5gr load for 158gr coated lead for 38sp. Sort of a medium/soft load that is cheap to shoot, easy to remember, and easy to calculate cost per round using the same load for both. I had piles of Unique and have lots of ammo already loaded with it. As I started to run low on inventory, I have been picking up CFE Pistol which seems to be somewhat readily available. Started low and have not had a chance to get back out due to extra dry conditions where we shoot outdoors---waiting for fall rains.

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"Tastes just like chicken"

I've used a lot of Unique in many, maybe all of the popular handgun chamberings over fifty or more years. Despite it's versatility, I've seldom found it the best for any particular cartridge. As close as I've come has been the .32-20 and .45 Colt. I no longer load the Colt cartridge, having lost all interest in it in favor of the .44 Special.

I think the last batch of .32-20 (rifle, but loaded down to revolver level) is charged with Unique, but I'm confident one of my few remaining handgun powders will be able to replace Unique perfectly from both accuracy and velocity perspectives.

Again, versatility is unmatched or close to it, but the single best for any one chambering? Possibly, but I'm not so sure...

If memory serves I've had decent loads with Unique in 45 ACP. And as many have said it's good for a lot but probably not the best with much.

Both my 2nd and third Edition Lyman manuals state that with 9mm Luger caliber and a 115 grain JHP you use from 4.4 - 5.8 grains of Unique. I would go around 5 grains and try that. Autoloading guns generally don't cycle and chamber well with minimum loads from my experience.

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S&WHF #946
S&WCA #3824

Black69, I used a lot of Unique in 9mm back in the day; 6.1 grains is definitely not a starting load. Why not start with something around 5 grains. This may or may not reliably cycle your pistol, but then you'll have a starting point. I used 6 grains as a top load with 115-124/125 grain jacketed bullets. This gave ~1250 FPS in 4" barrels, but I preferred the slightly slower Herco for top loads. Back then, I used 7 grains of Herco with the same bullets. Herco with the 115 gave 1300+ FPS depending on which gun, barrel length, etc. I've not seen any Herco for sale in a LGS for the last several years though, so perhaps not much of a consideration for loading now days..

Disclaimer: I am not a scientist, am not a ballistic testing laboratory, did not pressure test these loads. These loads caused no issues in my guns, but that was with my guns, using the Unique and Herco of that time...YMMV

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NRA Life, COTEP 640

Unique is my go-to powder for 9mm.

Appreciate all the input from all of you. I’ll be trying some of your recommendations. I may also try some polymer and see how that works out.

[I've not seen any Herco for sale in a LGS for the last several years though, so perhaps not much of a consideration for loading now days..[/QUOTE]

I bought a pound each of Herco and Green Dot last week from Midway USA. All of the Alliant powders have been around here so I am pretty sure your issue is regional.

Link: Alliant Herco Smokeless Gun Powder 1 lb

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S&WHF #946
S&WCA #3824

My current load is 4.5 grains of UNIQUE with 124 grain FP or 135 grain RNFP X-tream platted bullets. Accurate loads , low recoil.

Just to give you a hand, the newest Hornady manual lists the charge range for Unique with a 115gr XTP bullet as 4.3gr to 5.4gr. They list the OAL as 1.075" who h is probably where the crimp groove sits.

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Freedom is never free!!
SWCA #3437

LOL, Sierra took 16 years to come out with a new manual.

.

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Waiting for the break of day