superdude

The question is why you said that max book loads are conservative. Do you mean max book loads are not loaded to max pressure specs? Or that max SAAMI pressure itself is conservative compared to what a load can be loaded to? - meaning that one can load past max book loads. As Guy Neill notes, max book loads are often at max SAAMI pressure. The ADI load data for 9mm looks to be up to SAAMI max pressure. http://www.adi-powders.com.au/pistol/9mm-luger

Explain.

What is your load data?

Not really. I've found it to be very accurate in the 9mm.

Since you're loading for a compensator, select the powder that uses the largest charge weight for the velocity you desire. More powder weight means more gas and more gas means more downward pressure from the compensator. This is explained here: https://www.shootingtimes.com/editorial/compensators-pressure-gas/99170

Starline is at Brownells; https://www.brownells.com/reloading/brass/pistol-brass/38-super-comp-brass-100-bag-sku749018116-118586-218367.aspx and Grafs: https://www.grafs.com/retail/catalog/category/categoryId/4189 Hornady also makes 38 Super Comp. It's in stock at Grafs: see link above. And it might be in stock here: https://www.sportsmans.com/shooting-gear-gun-supplies/reloading-equipment-supplies/brass/hornady-38-super-comp-handgun-reloading-brass-200-count/p/1663057 Another option is Starline 38 TJ. It's in stock at Starline. And for more than you ever wanted to know about rimless 38 Super brass: https://www.ssusa.org/articles/2019/7/23/rimless-38-super-brass-everything-you-need-to-know/

No need to trim brass. Just push the bullet in deeper. That will emulate a 38 Colt case (Short or Long). As Service Desk notes, you can seat them flush. The reduced space by seating the bullet deeper will increase consistency.

#7. Have you determined WHY those rounds don't fit the case gauge? Method here: https://www.shootingtimes.com/editorial/reloading-tips-the-plunk-test/99389

Mine too. For some brass, I run them through the Lee FCD before I size them. That reduces the chance of a 'ring' of brass at the head which the Dillon die can make with heavily bulged cases.

What do you mean by rejects?

Use lead-free primers. (Easier said than done given finding ANY primers.)

Any powder works a compensator, but powders that use a larger charge weight (for the same velocity) work the compensator better. A slower powder will generally require more charge weight and will work better. But try it and see how it works for you. If you have slower powder that requires more charge weight, try them along side it to see which you prefer.

Google 'open gun' and check out the pictures. Lots of them. They are the quintessential race guns.

On this website it characterizes a gun with an optical sight and compensator - defined by Open Division USPSA/IPSC rules.

Carole, these are difficult times to find primers. Small pistol primers appear to be the most desired, if the posts on forums are to be used as a measuring stick. Our best advice is to watch frequently for them at local stores and every place that sells them on the internet. Sign up at those internet stores that allow you to be notified when they have some in stock, and act VERY quickly when you get notified because they will sell out VERY fast. Good luck.

There's no easy answer to this question. I'd have more confidence in 10-shot groups, simply because it's a larger sample size. If you want to delve into the issue of how many shots to have in your group, the two articles below will be more than you ever wanted to know. 5-shot groups: https://www.ssusa.org/articles/2019/9/25/accuracy-testing-shortcomings-of-the-five-shot-group/ 10-50 shot groups: https://www.nxtbook.com/nxtbooks/nra/ssusa_202102/index.php#/p/22

If you're looking for the most accurate load, focus on shooting from the bench. This is better at accessing mechanical accuracy = how well your gun shoots the ammo. Shooting offhand introduces all kinds of error into the process, something you want to avoid. You should shoot more than 5 rounds in your group. That's because 5-shot groups can vary in size, even when shooting the same ammo.

In some cases using the same charge with different bullet weights results in the lighter bullets going slower. The link below shows data for a 45 Auto. See Table 2. https://www.shootingtimes.com/editorial/power-factor-recoil-bullet-weight-gives-edge/99399

Google: 380 Auto load data Hodgdon Powder Western Powder Alliant Powder Speer Reloading Nosler, check out their Load Data Data manuals include: Sierra Hornady Lyman The 380 is a common caliber.

I wouldn't say load data is almost non-existent. Every major powder and bullet maker has 380 Data.

Another method is to alternate a (tumbled) fired case, a new case, a fired case, a new case, etc. The fired cases, which are still a bit dirty, will 'lube' the expander so the new ones won't stick.

Might be some useful information in this article: https://www.ssusa.org/articles/2018/1/9/how-to-use-9-major-in-a-short-barrel/

Generally what you're looking for with respect to practical shooting competition is whether the slowest round still meets your power factor requirement. At 130 power factor, you're good to go for minor with a minimum 125 power factor.

If they are the same load, combine them into one 20-shot string.