"Sweet spots"

[Infidel_319]

Ok, been hand loading many years, but for the most part, like the last 15 years, only rifle. Loaded handgun when I was in my late teens / early 20's. With my rifle loads, I almost ALWAYS find a LOW and HIGH sweet spot as far as accuracy goes. I was testing some loads in .357 mag and found that to possibly be the case for hangun too. Was using Win 231 powder, Sierra 125 grain jsp and cci550 primers. Excellent accuracy at 7.6 grains and again at 8.4 grains. I'll be using the 7.6 grain load as these are just for target practice. Some of the loads in between (.2 grain increments) looked like a shotgun pattern, not a good one at that.
Is this pretty normal with handgun as I have found it to be with rifle loads? Sorry for the dumb question, it appears I've already answered it for myself, just looking for opinions from more experienced hand loaders in handgun rounds. Thanks in advance.

 

[Nevada Ed]

In my 686 6" with cci500 primers, I got a very nice grouping with 8.1 grs of w231 and I stopped there with my 125gr Jhp bullets.

Since this is a medium burn powder you are near its limits in
the 357 magnum but it makes a nice medium hot load.

 

[1991a1colt]

I have seen groups shooting low and high poa/poi with different charge weights with the same weight bullets, but I have not seen groups open up wide with different charges. I bet it has to do with your barrel twist and bullet weight and velocity. I know a fast, heavy bullet can skid and not rotate well on shallow lands and grooves can cause all kinds of problems even keyholing. Reloading is like science because everyone's gun is different and there is so many variables that can cause accuracy changes. I have always heard that every gun likes a certain combination of components to be truly accurate. Its the experimentation that's fun and rewarding.
The one thing I do have to say is loading hot rarely wins in the accuracy department.

Sent from my Nexus 7 using Tapatalk 2

 

[AzRedleg]

Ok, been hand loading many years, but for the most part, like the last 15 years, only rifle. Loaded handgun when I was in my late teens / early 20's. With my rifle loads, I almost ALWAYS find a LOW and HIGH sweet spot as far as accuracy goes. I was testing some loads in .357 mag and found that to possibly be the case for hangun too. Was using Win 231 powder, Sierra 125 grain jsp and cci550 primers. Excellent accuracy at 7.6 grains and again at 8.4 grains. I'll be using the 7.6 grain load as these are just for target practice. Some of the loads in between (.2 grain increments) looked like a shotgun pattern, not a good one at that.
Is this pretty normal with handgun as I have found it to be with rifle loads? Sorry for the dumb question, it appears I've already answered it for myself, just looking for opinions from more experienced hand loaders in handgun rounds. Thanks in advance.

I've been loading handgun ammo for about 25 years, rifle for only the last few.

What you are describing is exactly the same as I have experienced over the years. Holding everything as constant as possible and changing only charge weights can result in surprising differences in accuracy with a small (.2 grain) change in charge weight.

There can be several "sweet spots" but usually one is a bit "sweeter" than the others.

I try to develop loads that deliver acceptable accuracy over a range of pistols although I do have loads optimized for specific handguns, especially if I'll be shooting 50 yards and beyond. I tend to load these handgun specific loads in small batches and the generally acceptable loads in large batches for plinking usage.

Some bullets are more sensitive to this phenomenon than others and some of my pistols and revolvers are more sensitive as well. The bullets I cast seem to be the most susceptible, and I suspect it is because it is difficult to hold alloy absolutely constant for the hobbyist using scrap alloy. I try to alleviate this by smelting batches of alloy as large as possible and noting the alloy hardness.

Some cast bullet designs have proven to me they are not very accurate regardless of the pistol, powder charge, primer, COL, or powder type utilized. Even these bullets have “sweet spots” but the “sweet spots” are not so “sweet.” These molds get sold, traded, or put in storage until I want to torture myself trying to find the correct combination that will yield decent accuracy!

 

[Infidel_319]

Thanks For The Input. Loaded Up Two Batches Of 25 Each. One @ 7.6, One @ 8.4 Grains. If No Major Difference Is Noted, I'll Stick The Lighter Load. Only Shooting Paper With These Anyway.

 

[Infidel_319]

In my 686 6" with cci500 primers, I got a very nice grouping with 8.1 grs of w231 and I stopped there with my 125gr Jhp bullets.

Since this is a medium burn powder you are near its limits in
the 357 magnum but it makes a nice medium hot load.

I think it makes about a perfect power target load, at least for me. Haven't chrono'd 'em yet but would guess around 1300 fps out of my 4" 586. Fun to shoot, accurate, still wouldn't want to be on the receiving end of one.

 

[garbler]

This has always been my experience too in 45 plus years of this pursuit. When you find IT like that, it really is sweet. I know myself I almost always run back to my reloading room and crank out fifty to a hundred and write in all down in my loading logs.

Last year I had something happen that has happened only once before to me. I have a very reliable load for a custom single shot 444 that just loves H-322. I could go up and down 5% and with Hornandy's 265 grain FP bullet and it would still print .500 to .750 all day. These bigger straight wall cartridges can eat up a can of powder so I always kept a couple cans of H-322 on hand. I emptied a can right down to the last case and opened the next not paying attention to batch # or anything since they were bought at the same time.

Next day at the range I set up my rest for a session with my favorite 444 and I am getting a spread that is close to 2-3" and not high or low left or anything but all over the place. Has to be a loose scope base or ring something mechanical I am convinced. Pull out my tools and check all screws and sight in again and I get the same thing at 100 yards. Well after a couple of very frustrating sessions I had to give up on that batch of H-322 as that Ackley barrel just would not play with it. I ended up going back to 4198 with a loss of velocity and not quite the reliable accuracy but starting to look like H-335 will work fine too. But that old batch of H-322 was magic. I now alway dump and mix my cans when they get to the last third and this really helps with consistency. I should also add I have a really good 4# can of 4756 but before this batch I had real pressure problems and accuracy issues with this powder back in the late 80's early 90's when I was shooting tons of 45acp in IPSC years ago.

Regards

 

[OKFC05]

Excellent accuracy at 7.6 grains and again at 8.4 grains. I'll be using the 7.6 grain load as these are just for target practice. Some of the loads in between (.2 grain increments) looked like a shotgun pattern, not a good one at that.

Having loaded W231/HP38 for decades in large quantities, these results strike me as odd. Of course, you don't give any numbers, so I don't know what range, group size, number of shots, or whatever, or what you consider excellent or poor.
At normal pistol distances, I just don't see groups going from 2" to 12" and back just on a few tenths powder charge change. And shooting just one group with each is poor testing technique, if that is what you are doing.

What range?
What group sizes?
Repeatability?

 

[Infidel_319]

Having loaded W231/HP38 for decades in large quantities, these results strike me as odd. Of course, you don't give any numbers, so I don't know what range, group size, number of shots, or whatever, or what you consider excellent or poor.
At normal pistol distances, I just don't see groups going from 2" to 12" and back just on a few tenths powder charge change. And shooting just one group with each is poor testing technique, if that is what you are doing.

What range?
What group sizes?
Repeatability?

Good point.

The two groups I really liked were both 5 shots at 10 yards and measured just over an inch. 1.16" I believe on the one, the other a tad larger. The "bad groups" were in the 4" range. Each load was shot in two five shot groups. Results were the same with both groups in almost every test with the occasional flyer. The worst group which I thought was strange was vertically about 4" and maybe 2" wide. This occurred both times I tested it. I think it was the 8.0 grain load.

 

[Infidel_319]

7.6 Turned Out To Be The Best. That's My New Target Load. MV Probably Around 1050 Fps But Its Fun To Shoot And accurate. Thanks For The Info Nevada Ed.

 

[OKFC05]

The two groups I really liked were both 5 shots at 10 yards and measured just over an inch. 1.16" I believe on the one, the other a tad larger. The "bad groups" were in the 4" range.

Just flipping back through my notebook, these results are far worse than any 125gr or 135gr jacketed bullet I have tried with W231/HP38 in .357 cases! Anything I've tried does 4" at 25yds. The Speer does 4" at 100yds.

I have used 7.5gr as a "walking around" light .357 load for decades before the "short barrel" bullets came out from Speer.
Now I use the same load under their 135gr SB bullets, and it will do under 2" at 25yds all day.

I do have the advantage of having a scoped 686 that I can rest and minimize human error. It makes a great ammo tester compared to iron sights, hand held.

As I approach 8gr, there is a little increase in dispersion, but no tendency to alternate "good" and "bad" groups with slight increases of powder.

 

[Nevada Ed]

125gr Jacket bullets work but are a little pricey for my taste
and I use lead for killing paper critters.

4.8 grains of bullseye or w231 is a nice light load and 4.7c
grs of Trail Boss at 780 fps is also very accurate in my 6" magnum.

I never tried down loading w231 in my magnum.............(357 case )
would like to see a picture of the 7.0 or 7.4 grs of w231, though.
Good shooting.