What is critical to handgun cartridge accuracy?

My goals for handgun cartridge loading recently shifted to accuracy.  A desire for better understanding is what prompted me to join this forum.  It has been my observation that when handloaders are focused on producing a bulk quantity of ammunition, we can be efficient and productive.  When we begin to pursue accuracy, we can pursue it with a variety of practices that can leave us wondering if we're just wasting time.  I've attempted to test a few things myself, many of which have advantages that have been statistically hard to pin down.

Let me quantify a bit.  I shoot 357 Magnum from a revolver.  I get 5-shot groups at 25 yards that can be as small as 0.5" x 0.5".  If I could get 50-shot groups that size, I wouldn't have any further questions.  While I appreciate that there is a great deal more to small groups than just the cartridge, the cartridges are all this topic is about.  Also, I do shoot at 50, 75 and 100 yards, but test primarily at 25.

I decap, resize and expand case mouths on a progressive press.  My Lee press is flimsy, but I can't see how using a single-stage or any other higher-precision press for these steps would produce a better result for a straight-walled cartridge.

A single non-tapered carbide ring will size the part of the case that hold the bullet (the neck) small enough for good neck tension so there is no bullet set-back or crimp jump under recoil.  If the same ring is used to size the body of the case, it will size it down to a small diameter.  Because the bullet is not inserted below the seating depth, this portion of the case body is not expanded by the insertion of the bullet.  The cartridge will have a narrower "waist" between the case head and the base of the bullet.  Theoretically, this could result in poor or slow case sealing against the chamber wall.  I know of three solutions: a tapered steel die, Redding's Dual Ring Carbide die, or using two dies each with a different size carbide ring.  I use the third solution, but I have not compared the results.  Has anyone here?

I formerly used a case-activated drum powder measure but I was bothered by its inconsistency and I suspected it as contributing to rolling the edge of the case mouths.  I bought a Harrell's pistol powder measure and now I use that.  The charges are more consistent.

Does trickling every charge improve results?  Drops from the Harrell's are typically within a tenth of a grain.  In my testing, I saw results that made me suspect that the powder type lowered SD and ES more than trickling.  HP-38 and Titegroup had lower SD and ES than Power Pistol, Blue Dot, Longshot, 2400 or N105.  The faster powders yielded SD's around 25, whereas the slower powders were 50 or worse.  It seems that the powder measure would make a proportionally smaller deviation in the mass of a high-volume powder charge than it would in a low-volume powder charge.  Therefore I suspect in this situation that combustion characteristics are more critical to the consistency of results than powder charge mass consistency.  Has anyone found it necessary to trickle to get the most accurate handgun ammunition?

I've been using XTP and Golden Saber JHP bullets because I have them.  I also have Speer TMJ and Berry's plated.  What do I need for accuracy?  Can I realize an improvement just by switching bullets?

What about bullet seating?  What is necessary in seating the bullet to obtain the best results in accuracy?  Some benchrest rifle shooters are dismissive of the importance of concentricity and some successful competitors don't measure it.  It seems that bullets going into the forcing cone without concentricity would be an opportunity for poor consistency.  Should I be checking every round and fixing or sorting them?  Should I just be checking to verify that my dies and processes are pretty good?  Or should I just forget about it?

I typically seat to a high position on the crimp groove.  Should I be testing different seating depths to find a range that produces better accuracy?

I seat and crimp on a single stage now.  Since I moved away from the auto powder measure, my cases are off the press in a loading block.  Instead of re-inserting them into the progressive (which has a case-feeder), I bought a single-stage to seat and crimp.  Unfortunately, the single-stage I bought has some defects and I will need to return it.  It has a big ding in the ram and the machined surface that the die lock ring fits against has a machine mark like a swirl that is uneven by a few thou.  I need to return it before the end of January, but right now there are no more in stock.  I could wait or find an alternative.  I haven't seen evidence that one press can produce more accurate ammo than another press, but I"m open to advice.

I use a single stage Lee press for loading .38 special for my K38 and Model 52. I know reloaders that load the same cartridges I do progressively. I think if you take the time to set up and test your progressive press and run QC tests periodically, you can really make great ammo and make it much faster. I load single stage because that is what my feeble mind is able to handle and I enjoy the process. Either way, it seems you have a good handle on the process and will be safe. Not advice, just my thoughts.

“. I've been using XTP and Golden Saber JHP bullets because I have them.  I also have Speer TMJ and Berry's plated.  What do I need for accuracy?  Can I realize an improvement just by switching bullets?“. 


Switch away from the Berry’s plated,  in my experience accuracy was not up to par.


In reality, pistols (including revolvers) will digest and shoot well with all kinds of different powders and billets.  As in rifle 90% of the accuracy is in the bullet.  Good bullets will shoot well, bad bullets won’t no matter how hard you try.  So long as they Are not mixed, cases don’t matter.  Powder is 8%  & primers are maybe 2% of the accuracy puzzle.  In cast bullets, the maker has a big influence.  Most are good, some are excellent, a few are better used as fishing weights.

Starting with a GOOD pistol....just sayin' lol
Jon

juniper:
 
Welcome to the Bullseye-L Forum, dedicated to the sport of Bullseye shooting!

Most of the posters here are in it for the precision pistol shooting (bullseye) sport, rather than precision reloading.  However, there are a number of precision reloaders on the list and they provide lots of information and suggestions.  

That's one the the reasons there are over 2,200 topics and almost 29,000 posts in the Ammunition Discussion of this site alone.  A search and general perusal of this section will give you more information than you can dream of for your questions and generate about a thousand more questions.  You will notice that a lot of people try a lot of things to get better at reloading in hopes of getting better at shooting.  But each to his own path to their individual idea of happiness. 

As to some of your specific comments / questions, I have some random responses.  You will never get a 50 shot group that beats a very small, but statistically insignificant, 5 shot group with dam near any gun / ammunition combination, no matter how consistent you try to be. The statistics just aren't there.  Just shoot 20 to 30 shot groups with a Ransom rest to see how the load is working out and move on.  

By the way, that "wasp waist" effect doesn't really affect accuracy at all for pistol rounds.  On the other hand, you can't be sloppy or use cheap bullets or crappy cases and expect miracles.  Really the only thing necessary about seating the bullet is to get a good bullet the right diameter for your gun; then find the right length and crimp for your gun / load and not screw up the bullet any more than you have to (crimp properly).   

And the most critical thing contributing to accuracy is consistency, since we don't have enough time to find perfection.

Good Shooting and welcome to the list. 

CR

You may find this thread of interest:

https://www.bullseyeforum.net/t3064-brass-variation

Wobbley wrote:“. I've been using XTP and Golden Saber JHP bullets because I have them.  I also have Speer TMJ and Berry's plated.  What do I need for accuracy?  Can I realize an improvement just by switching bullets?“. 


Switch away from the Berry’s plated,  in my experience accuracy was not up to par.

 
I'd add couple of qualifiers here.  Firstly distance, - up to 25Y plated bullets will perform adequately even in 357M.  After that mark it is more problematic, because.... - Secondly - for 357M to perform accurately beyond 25Y velocity should be above 1200fps.  This is a border line for plating to withstand, even though Berry's and X-Treme claim that their heavy plating bullets can fly with up to 1400fps.  So plated are hit and miss beyond 25Y based on quality of plating.  That is my experience with plated, yours might be different.  I had good results with Magtec 158gr JSP, Speer 158gr JHP and Hornady 158gr XTP on top of 13.8gr of H110

AP

Accuracy?
Gun
Bullet
Powder/charge
Practice
With hangubs, most accuracy is from the shooter.
Bullets:
JHP
Wadcutter
Semiwadcutter
Flatnose
Round nose

Jacketed/swaged, cast, and, trailing the rest, plated.
I tried lots of plated bullets with 3-12+" groups. My own cast gave me 0.75-3" groups. Commercial swaged gave me 0.7-1.5". Finally, JHP gave me 0.7-1.5" groups--all at just 25 yards. Ymmv, but I'm not buying plated bullets.

I am going to offer something that no one measures: bullet stability and concentricity. There was a Vern Juenke bullet concentricity machine, but it is no longer available. This thread has a few users talking about their results

http://benchrest.com/showthread.php?98076-Vern-Juenke-ICC

Vern Juenke machines can be expensive

https://forum.accurateshooter.com/threads/juenke-internal-concentricity-comparator.3950245/

The thing is, if the center of gravity of the bullet is outside the axis of rotation, the bullet is not going to be as accurate as a bullet with the center of gravity and axis in line. And no one really measures this, because the equipment is not available.

Also, bullet stability is hugely important, the good thing, the bullets we use have all been shot out to 50 yards and are well characterized. But see what happens the further you go out.....

fwiw, I use a Redding T7 turret press, for maximum rigidity and consistency.  I load in batches, one operation at a time for the batch, on to the next operation, all in one session, batch size depending on time available/energy level, usually batches of 50, sometimes 100.  All of my dies, once set, are very consistent, since I am not changing anything.  The Redding is generally regarded as the strongest. most rigid turret press out there, and you can buy additional die heads for more calibres if you choose.
I use dippers for my powder, and a scale, just gently tapping in the last couple of granules of powder to get the scale in balance.  I think this gets me better than 1/10th grain accuracy.  I am not worried about speed of production., I enjoy time at the reloading bench.

Well, Revolvers are known to have one maybe 2 chambers that aline with the bore of the barrell well enough to produce consistently good groups. Most old timers that shot revolvers at the nationals would test the chambers to find the one that produced the best group and marked that chamber on the cylinder and used that chamber only for 50 yard slow fire. Along with that there seemed to be one chamber that was the poorest. it was not used during TF or RF unless it was in the middle of the 5 chambers, So, for a revolver, you could spend more time and money on producing better ammo and not see the results in group size if you used the poorest chambers.

Dont know if you have heard or tried this, however something you might want to give a whirl. 100-105 swc cast boolits(swaged would prob be better, if you can find)),.38 special. Suggest BE, IMR Target, Nobel Vectan BA10, or 700X powders. Range 1.9-2.2 grains. Same name cases. Seat the bullet 3.0mm -3.125 mm below case mouth and apply a very  minimum crimp(i use a roll crimp). Your choice of primers(what you can find nowadays). Have been experimenting with this loading and at 50 yards getting one hole or near one hole groups, with the occasional flier out of a ransom rest. This is something I picked up from a friend in Canada that shoots PPC and is a high master competitor. Of course each gun is different. The key to good accuracy from a revolver is that all cyl throats the same diameter and good forcing cone angle with a a good muzzle crown. Cyl to bbl ranging is critical too of course. I am sure other factors enter into the picture, but if you have a good revolver should get some good results with this loading.

Only my two cents.

Forget the plated bullets.    I tried enough to save you the time.

For a "flimsy progressive press"  I found the difference in case length can have some effect on completed round consistency.  A long case, or one that sizes hard, will make the up stroke be a little less.  So no big deal?  While I am sizing the one case, another station is seating the bullet.  This can result in a longer bullet.  Now lets say the next case sizes easily.  The now slightly long  cartridge is in the crimp station and gets crimped more than the rest.   Tolerances can stack up.  

My hat is off to you for shooting 1/2" x 1/2" 357 magnum @ 25 yards.  That is some good shooting and reloading.

I doubt you will ever see a difference in accuracy from thrown charges and weighed charges in a hand gun.  

SD doesn't seem to make much of a difference @ 25 yards.  

For Bullseye shooters, putting the bullet in the 10 or X is about mental and physical ability.    

I read the whole reloading forum.   What I learned is have a good gun and spend your time practicing instead of searching for the holy grail load.  Once I have a decent gun, most anything will shoot at 25 yards and the good stuff shoots great at 50 yards.  Look at the loads listed by the pros.   Most are standard loads, like 3.5 to 4 grains of bullseye under a good quality  cast 200 grain semi wadcutter.  

David

I am somewhat surprised at the mentioned tolerances of as much as a tenth of a grain and the lack of discussing thousandths of an inch in COAL. Personally, I never allow a deviation of more than +-0.02 grains or 1/1000 of an inch working my Präzipress and frequently pouring back powder into a manually operated tweaked Dillon powder measure. It takes time, but I just can't help myself. Admittedly I am not even proud of my tolerances here as I know they can easily be improved, but I decided to draw the line at the aforementioned tolerances.

I would try different bullets in combination with different powders but first and foremost certainly tighten tolerances to check if there is any improvement with the combinations you are already using. When trying different bullets, you would also have to meticulously measure each individual bullet for weight and measures, and then possibly do some grinding & polishing. Also thorough measuring of each individual case.

Then there is measuring the hammer strike force consistency. For maximum accuracy there must be a controlled hit on the primer, which, unfortunately cannot really be checked for minuscule variations.

In addition to this, the shooting must be performed in a room without ventilation that can disturb the air, as outside, there can always be the smallest movement of the air sideways or vertically which may vary between shots.

Jeez guys, the point of reloading is to explosivly empty the cases, not to nit pick the reloading process... turret presses... 0.02grain powder tollerances... DO NOT MATTER.

If your hobby is reloading and not shooting, send me the ammo and I'll send back test reports and fired targets.

I have a different fairly simple theory on reloading and accuracy.

I bench the pistol and shoot a ten shot group that is easily X ring. Then I stand and shoot a ten shot group. Until the two groups match, there isn't anything wrong with the ammo or reloading process worth worrying about! 

I recall an excel spreadsheet that a fellow competitor set up, it simulated the effect on target (as score) of the shooters spread with the ammunition´s spread overlaid.
I think he included simulation for ill adjusted sights as well.

The purpose was simply to in some way quantify what effect ammunition accuracy had on score compared to shooter ability.

Wish I could find it but I´m not hopeful, it was maybe fifteen years ago.

10sandxs wrote:Jeez guys, the point of reloading is to explosivly empty the cases, not to nit pick the reloading process... turret presses... 0.02grain powder tollerances... DO NOT MATTER.

If your hobby is reloading and not shooting, send me the ammo and I'll send back test reports and fired targets.

Do you live around Chicago? As one of those guys with a Redding turret press and metering charges within a couple hundredths of a grain I do have about as much fun developing the equipment as I do shooting it. But my shoulder is injured and I need someone to test which of all these new loads is heading in the right direction!

TureB wrote:I recall an excel spreadsheet that a fellow competitor set up, it simulated the effect on target (as score) of the shooters spread with the ammunition´s spread overlaid.
I think he included simulation for ill adjusted sights as well.

The purpose was simply to in some way quantify what effect ammunition accuracy had on score compared to shooter ability.

Wish I could find it but I´m not hopeful, it was maybe fifteen years ago.

Hello TureB,

If you search this forum for this thread:

Accuracy calculations- points lost to inaccuracy.

You will find a lengthy discussion on the topic you note.

Good luck.

SingleActionAndrew wrote:
Do you live around Chicago? As one of those guys with a Redding turret press and metering charges within a couple hundredths of a grain I do have about as much fun developing the equipment as I do shooting it. But my shoulder is injured and I need someone to test which of all these new loads is heading in the right direction!

Sorry, 650 miles north west of you... I do have access to an indoor 50 yard range with a ransom rest though... makes winter here a good time to test ammo...