How easy is it to create reduced loads? Being a newby I don't know if it's simply a matter of using less powder,or if doing so might create space inside the cartridge that could result in a dangerous condition. I do understand that a bullet not leaving the barrel could be disastrous on the next shot,and I understand that bullets are designed to expand at specific speeds. I've just never read much about creating reduced loads lower than published manual starting loads.

This question arises wondering how difficult it would be to load a 358 Win to 35 Rem levels or even below for a child, and creating reduced loads for children in general. I do understand that sometimes different bullets or even pistol bullets or cast bullets may be necessary if hunting with reduced loads.

I consider there to be 3 fairly typical levels of "reduced loads".

One would be simply looking at the manuals you have on hand and picking a tested load that shows a lighter charge weight and generally a corresponding lower velocity. I do this with my 35 Whelen to get 358Win ballistics. Nosler showed that the charge weights for RL10x could go much lower than other powders, I had some on hand, and it worked out well. I see RL7 on their online data for the 358Win, and the charge weights/speeds are light when compared to the other choices.

The second would be to use either the "4895 rule", which you can find online, or to get data from others regarding other faster-burning powders that only require 2/3 of the typical charge weight of a common full house load for slower-burning powders. 4198 is commonly used in other 308 and 30-06-based chamberings like the 7mm-08, 308, etc. This is how some factory light load ammo is built. My 12 year old uses these loads.

Lastly, you have the "powder puff" loads, like Blue Dot and Trail Boss. These burn very small amounts of fast-burning powder. I've used the Blue Dot loads I got here from Seafire to good effect, but also picked up some Trail Boss recently. IMR had a process detailed online where you can load TB in rifle cartridges up to a level where it is not yet compressed and it is still safe (TB is super bulky, on purpose). I know it's common to be using 12-15gr of TB in other .308-based chamberings for ultralight loads. This level of recoil/report is great for youth to get some target practice before maybe moving up the the second tier of reduced loads that offer a bit more speed. My 8 year old uses these loads.

using the correct powder is the first choice......read Hodgdon's info using the 60% formula with H4895

Trailboss is another reduced load powder........follow load info........do not compress Trailboss.......

With TB....you fill case to base of bullet....not compressing......

https://www.hodgdon.com/wp-content/uploads/2016/11/h4895-reduced-rifle-loads.pdf

https://www.loaddata.com/articles/PDF/LD-36%20Haviland%20LR.pdf

yes........Bluedot works well too.............

300 BLK......Ruger bolt gun.......8.5/BD & 110 Nozler..........

223..........12/BD & 53 V max.........

nice quiet loads around the house.........

Like JPro said it depends on the level of reduction you want. A lot of mine are "somewhat reduced."

For example I shoot a lot of 308 Winchester. Full power loads using something like Varget give a 168 about 2700-2750 fps from a 24" barrel. OTOH, exceptionally accurate loads may be constructed using below max charges of IMR3031 for about 2550 fps which is similar to old school Lake City match ammunition. Such loads are easier on the brass, gun and shooter and still provide plenty of steam for deer hunting purposes past 300 yards.

Theoretically, you can use any powder in any case and get some kind of non-dangerous result. Satisfactory results are another story. I began studying the writings of Phil Sharpe and other writers of nearly a century ago when I began getting serious about reduced load work-up and shooting. Most any fast-burning handgun and rifle powder will work in all but the big magnum cases, but make sure you have a good idea of what you are doing (study manuals, books, ask questions for enough time that you KNOW what will happen when you pull the trigger) before stepping into the pursuit. It's a hell of a lot more fun for me than just picking a set of data and following it, and it's far more satisfactory than just following what the manuals contain. I've had largely great results, and a few surprises, not all of them unpleasant. I studied for a couple hundred hours before I began though.

Not that I would do anything without knowledge and research,but just so I have an idea of what is going on, what would happen if you were to reduce a known load by half using the same powder? I'm trying to learn what the extra space inside the cartridge would do to the pressure levels.

That depends a good bit on the particular cartridge and powder. For example, using a 60% of max charge of H4895 in a 308 is a recommended youth load in a 308, but cutting a charge of 7828 that much in a 300 Wby. will probably make trouble.

I wouldn't know, and I wouldn't do it. That's not how powder reduction for velocity reduction is done. The pressure/powder density will likely be well under that needed for an effective burn, and anything from a secondary explosion to a stuck bullet to a delayed fire may occur. The way to reduce is to step up in burn rate, usually quite a bit, in order to get the desired result (accuracy, consistency, safety).

Since it IS rocket science, and since you DON'T know what you are doing -- please use only published data for reduced loads. Rolling your own is not a trick.
The very first thing you are likely to do is produce buckled brass commonly found due to blow by gases -- the bullet isn't "sent forward fast enough", so to speak, to seal the case against the chamber/barrel.
Similarly, trying to make homemade WAG recipes by duplexing powders is also STUPID. Unless you have a full grasp of the physics (which I do not), stick to loads others have found to work. Even then, work up for maximum loads and don't go below minimum loads for any given bullet/powder/primer/case combination. Sorry for the shouting, but on the internet you sounded kind of tentative...

I'd look at using 158 jacketed or cast bullets and a pistol powder. I use 158 JFP's in my 35 Whelen for plinking/practice rounds.

Suggested read:

http://www.gmdr.com/lever/lowveldata.htm

I've used Unique, Blue Dot, W-231 and Trail Boss in this application. W-231 worked best for me. 1" at 75 yds for 5 shots. Right at 1,100 fps over the chrono and it's a pussycat to shoot.

I'm sorry,I thought I was very clear that I wouldn't be doing any experimenting without a basis of previous knowledge . I simply asked about how a smaller amount of powder would effect pressure to try to get some grasp on the dynamics. I didn't think I was tentative at all,at least about not doing what you are cautioning against. Rest easy,I am not a fool. I do however appreciate the reasons for your abundance of caution,and I thank you.

Are there trusted sites dedicated to development of reduced loads similar to the manufacturers load data sites?

I'd look to the 200gr FTX as a reduced load hunting bullet, as it's fairly sleek and designed for 35rem speeds.

Also, Hodgdon currently lists a SR 4759 load for 200gr bullets of 29.5gr for 2,170fps. This is in their online guide.

That load, with the 200FTX is actually pretty flat. JBM says a 125yd zero is 1" high at 100yds and 1.5" low at 150, where it is still going about 1,800fps. That'll kill something without kicking too badly. I've seen it work in the .35rem.

There are old reloading and powder manuals that contain some data that is informative, such as the old IMR data. Search for IMR load data pdf online. You get results like this:

http://pdf.textfiles.com/manuals/FIREARMS/imr_reloading.pdf

Go to the rifle data on page 50, and you'll see max data for the 358 using powders like 4759 and 4227 that mimic 35 Rem with full pressure charges.

again.............

https://www.hodgdon.com/wp-content/uploads/2016/11/h4895-reduced-rifle-loads.pdf

There are a multitude of powders one can use for reduced loads. 2400, 4227, RL-7, 4759 are just a few I have on hand for that very purpose. Also pistol/shotgun powders from Bullseye on up work dandy for low velocity loads in medium sized cases. About 90% of the shots I fired over the last 40 years have been reduced loads. I see no point in creating a dearth of muzzle blast and recoil every time I pull a trigger when the goal is to make small holes in paper. No risk in leaving air spaces with those fast powders, they do require one to tighten up one's quality control protocols at the bench though. No big deal.

I dislike Trail Boss. Worst "bang for the buck" of any reduced load powder, plus I never ever got as good accuracy with it as I did with any number of other powders. I gave away the last two pounds I had.

The data is out there. Exercise your google-fu and find it.

As for bullets, yes jacketed work swell. So do cast lead and those only cost you your time to make them, reducing your costs smack into the realm of .22RF ammo costs.

H4895. You can go as low as 60% of max load. Velocity will be close to that same percentage. I've used it a lot in .243, 270, and 30-06. That's the best route to take.

I have used both the starting load and the 60% H4895 approach.

I have had success with both methods in the 22-250 and 270 Win and see no reason to mess with TB. The blue dot method intrigues me, have not gotten around to trying it.

Very pleasant to shoot and worked very well on deer and antelope for when my sons were younger. Accuracy was never an issue.

IMR4198 is much simpler to use than 4895 for reduced loads, IME.

Though XMP5744 is easier yet, especially in that case size/bore diameter.

I have never messed with IMR4198 or XMP5744. But I have enough H4895 to reload reduced loads for a very long time.

Very safe, that's the main thing.

If you guys will check out the pdf IMR data link I posted above, you'll see that IMR tested and produced data for most of their powders in most cals, such as 4350 in a 44mag. It is highly informative, and useful for moving up or down the burn rate scale to produce different results.