9mm 124Gr. RMR Nuke and Canik Rival Min. OAL Concerns

[CurryCornDog]

When pressure testing is done to publish load data, actual pistols/firearms are rarely used. Instead, "universal barrel fixtures" that accommodate multiple caliber barrels are used which are single action that do not feed from the magazine.

So OAL/COL listed on published load data simply means that was the cartridge length used for pressure testing that day for the particular test barrel. But using this length does not ensure finished rounds will fit our pistol barrels nor reliably feed from magazines.

If you are loading for revolvers, you can use the listed OAL but more often, you will use the OAL that will allow roll crimp into the crimp groove unless you are using taper crimp.

But if you are loading for semi-auto pistols that must feed and chamber from the magazines, we must first determine the Max OAL allowed by the barrel then the Working OAL that will reliably feed and chamber from the magazine and this is the cartridge length we use for conducting initial powder work up. (And if the Working OAL, or rather bullet seating depth, is shorter than published, we can consider reducing the start/max charges by .2-.3 gr to compensate, depending on the difference in bullet seating depth, calculations for which we already addressed in previous posts)

And if powder charge that produces smallest groups is not at max charge and you want to squeeze a bit more accuracy, you can incrementally decreased the OAL/bullet seating depth by .005" to see if accuracy improves/group size decreases. If group size gets smaller, use the shorter OAL. If not, use the longer OAL.

These are load development steps match shooters use to determine accurate match loads. The last step of incrementally decreasing the OAL is further used by bullseye match shooters (Or those that want to pursue the accuracy rabbit hole) to where powder charge/shorter OAL results in lighter recoil loads to require reduced recoil spring rates.

An example of this is my 9mm reference load development using 115 gr FMJ RN and W231/HP-38:

• 4.6 gr and 1.150" will reliably cycle the slide and start trending accuracy of group size
• 4.8 gr and 1.150" will produce smaller groups
• 4.8 gr and 1.140" will produce smaller groups
• 4.8 gr and 1.130" will produce even smaller groups and this is my current 9mm reference load (But there are other powder loads that are even more accurate using Bullseye/Titegroup/WST/Sport Pistol/WSF/BE-86)
• 4.6 gr and even shorter 1.110" will produce comparable accuracy if savings of powder is desired (When you are loading tens of thousands of rounds, .2 gr savings per round adds up)
• I will not load 9mm with 115 gr FMJ RN shorter than 1.100" because due to tapered case, neck tension will start to decrease with shorter OAL and bullet will simply drop into the case

Man, practical application of theory sure does bring about real working knowledge over time. It all clicks now. This is good news.

It makes sense why you asked me about setback. These are simple things to know, and now I'm understanding the "why" when you put it all together.

It's a chess game. Each move must be criticized in order for every part to move freely for the best yield possible. Something out of whack makes everything out of whack, hence the setback question. I'm starting to see it now!

Deeper seating has the chance of flattening the taper crimp, thus potentially decreasing neck tension which may push the bullet all the way back to bad day territory each time one enters the chamber. If one wants to truly know their margins, they must know the size of the cartridge at the last moment before sending the bullet.

If powder charge is too high in a set back chamber= kB. So, in a way, powder+ NOT case chamber size start, BUT post setback case chamber size after loading = your actual, true-to-life working OAL from round to round. Or thereabouts.

Such a simple concept.

 

[LiveLife]

Man, practical application of theory sure does bring about real working knowledge over time. It all clicks now.

Glad to help a fellow THR member.

 

[CurryCornDog]

Glad to help a fellow THR member.

Much appreciated, man. If you're not an instructor in real life, the world is missing out on some real talent lol.

 

[LiveLife]

Much appreciated, man. If you're not an instructor in real life, the world is missing out on some real talent lol.

I am retired from working 26 years for three state of CA government agencies mostly as staff/senior analyst, compliance coordinator, federally certified surveyor of hospitals/health care facilities, project support manager and director of field facility of 120 staff and wrote my share of policies and procedures, best practices guide (Some of which were adopted and went statewide) and provided endless amount of training.

I have a standing offer to work as a Retired Annuitant from branch director as statewide training supervisor for one of the agencies I worked for but wife won't let me do it.

So I just play with puppies and do various projects around the house for wife and on occasion, punch holes on paper (40,000 rounds of 22LR and counting for "Real World" testing threads).

And supporting THR threads and doing beta testing for Lee Precision is "fun hobby" diversion.

 

[LiveLife]

I guess I am still "instructing" ...

While shooting USPSA Limited/Limited-10/Production divisions, I did "instruct" sharing with hundreds of people on defensive point shooting without charge while providing my own reloads as "Pay It Forward" - https://www.thehighroad.org/index.php?threads/flinching-drills.864546/page-2#post-11416785

And now retired, I primarily focus on sharing natural point of aim synchronization "instruction" - https://www.thehighroad.org/index.p...g-aid-against-flinching.912566/#post-12464404

And during past 30 years, I have helped set up countless new reloaders with PIF reloading start kits which I continue to do so.

 

[CurryCornDog]

I am retired from working 26 years for three state of CA government agencies mostly as staff/senior analyst, compliance coordinator, project support manager and director of field facility of 120 staff and wrote my share of policies and procedures, best practices guide (Some of which were adopted and went statewide).

I have a standing offer to work as Retired Annuitant from branch director as statewide training supervisor for one of the agencies I worked for but wife won't let me do it.

Damn. With the crazy convoluted laws CA has cooked up, no wonder you're good with intricacies.

 

[LiveLife]

Damn. With the crazy convoluted laws CA has cooked up, no wonder you're good with intricacies.

Wait until you meet my "crazy" wife of 28 years ... ... She is always contemplating what "honey do" project to pursue next. ... And oh yes, she is fully mastered in point shooting and can hit anything that moves inside the house ... She has become "One" with her Glocks ... Her favorite line is, "Isn't it time to go shooting?"

 

[Jim Watson]

I was looking through Hodgdon and saw an interesting thing.
I have always thought of Hornady HAP as just an XTP without the nose cuts, but Hodgdon shows substantially different results, the HAP runs up pressure at lighter powder charges and gives less velocity at the maximum.

A chronograph would be a good investment as long as you did not use it for Quant Suff loading and overload to get your desired power factor. Low velocity at a top load is a sign to change components, not go beyond the book.

 

[mdi]

I'm confused as to what this means. It is not a suggestion, but merely a report? I'm not terribly sure what the difference is. Does that make it a hard rule to the min load? An arbitrary min they figure as a "close enough/safe" min?

Reloading manuals are reports from the testing with the components listed with the data listed (bullet type and seating depth, etc.). A "report" is "This is what I did". A "suggestion" is "I think you should do it this way".

 

[higgite]

Reloading manuals are reports from the testing with the components listed with the data listed (bullet type and seating depth, etc.). A "report" is "This is what I did". A "suggestion" is "I think you should do it this way".

They do suggest max and min loads based on what they found at those loads with their firearms and components. Their max and min suggestions aren't necessarily the max and min they tested, but the max and min that they suggest based on what they tested.

 

[mdi]

I believe they report what they determined to be "min and max" pressures for the loads tested...

 

[Jim Watson]

The manual very seldom shows a "minimum" load, all I know of offhand is H110/W296.
They show a "starting" load which is in most cases 90% of the maximum.
Lyman is different, they show some starting loads way down from the maximum or factory equivalent.
Speer shows three loads, looks like 100, 95, and 90% of the maximum.

I am loading .45 ACP Minor/Midrange about 70% but I once tried for reduced 9mms and nothing under 88% would cycle the slide.

 

[CurryCornDog]

Wait until you meet my "crazy" wife of 28 years ... ... She is always contemplating what "honey do" project to pursue next. ... And oh yes, she is fully mastered in point shooting and can hit anything that moves inside the house ... She has become "One" with her Glocks ... Her favorite line is, "Isn't it time to go shooting?"

Ha! That's some relationship goals right there for anyone to strive for. If that ain't a testament to a working marriage, I don't know what is. Don't piss her off, my guy! I'm sure I'll still keep needing advice!

 

[CurryCornDog]

Reloading manuals are reports from the testing with the components listed with the data listed (bullet type and seating depth, etc.). A "report" is "This is what I did". A "suggestion" is "I think you should do it this way".

That's fair.

 

[CurryCornDog]

The manual very seldom shows a "minimum" load, all I know of offhand is H110/W296.
They show a "starting" load which is in most cases 90% of the maximum.
Lyman is different, they show some starting loads way down from the maximum or factory equivalent.
Speer shows three loads, looks like 100, 95, and 90% of the maximum.

I am loading .45 ACP Minor/Midrange about 70% but I once tried for reduced 9mms and nothing under 88% would cycle the slide.

That's good to know and makes sense. With some of the spicier powders having razor thin margins, it only makes sense that falling slightly short or heavy would make a big difference.

 

[ddc]

Wow, this thread is a perfect mini info-dump for the new reloaders.
Lot's of stuff here that would take some time to accumulate piece by piece.
Just reading it has been a great little refresher course for me.

 

[LiveLife]

Wow, this thread is a perfect mini info-dump for the new reloaders.
Lot's of stuff here that would take some time to accumulate piece by piece.
Just reading it has been a great little refresher course for me.

We just wanted to get new THR member @CurryCornDog off to a proper start to produce accurate IDPA match loads and defensive "practice" rounds.

Much of source information are compiled in this thread for your reference in producing consistent/accurate rounds, particularly for match shooting - https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11400667

Most popular USPSA match powders by percentage are listed on this 2021 equipment survey (Survey stopped listing powders by name starting 2022) - https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12415502

Case fill calculations/OAL/bullet seating depth from this thread - https://www.thehighroad.org/index.p...er-target-published-load-data-for-9mm.870180/

One of these days, we will compile all these threads with verifying myth busting objective measurable and repeatable data into some sort of e-book to use as ready reference published on THR for future generations of reloaders (My retirement "Pay It Forward" project for THR ).

 

[rfwobbly]

LiveLife did an excellent job of breaking it down. But guys seem to really "get" the point with graphics. So I'll sprinkle some on.

Thank you for the reply! A couple things, if i may ask for clarification.

Also realize:
► The OAL shown in your load manual is not a suggestion. It is part of the Load Data used in the manual, and the lab crew is merely reporting the OAL they used during testing.

I'm confused as to what this means. It is not a suggestion, but merely a report? I'm not terribly sure what the difference is. Does that make it a hard rule to the min load? An arbitrary min they figure as a "close enough/safe" min?

There are 2 main components to Chamber Pressure: 1) amount of powder, and 2) the volume it's confined to. If you're going to publish a book saying "this load is safe in your gun" then you had better report both the amount of powder and the OAL (which is the easiest way to describe volume under the bullet). In reloading, Chamber Pressure is our primary (ie. main, No.1, basic) concern because we don't want the gun to blow up and kill us. The experiments that make up the book then, must report the weight of the powder and the OAL.

But in all auto pistol cartridges, useable OAL is a range, not a single point. The Lab that did the experiments is NOT saying "this is the only OAL will work" or "it's the perfect OAL and you should use no other". And yet in each one of these treads someone always speaks up and says "Just use the OAL listed in the manual. That's the best OAL." The book never said that.

Here's a modern parable to illustrate: If you write that your child learned to swim in 3 feet of water, does that mean that ALL swimming pools have to be emptied / filled to the 3 foot level before ANY child can learn to swim? No! There's a wide range of water levels that can be used. You reported 3 feet, but that statement is not a suggested level for the rest of the world.

► Given: 1. All chambers are cut differently. 2. All bullet makers produce a bullet of slightly different dimensions. The inner limit Max OAL is a result of how the unique bullet fits into your unique barrel. Only the person with both the bullet AND the barrel can determine this dimension with any precision. IOW, no person here can answer your question; each individual reloader must make these measurements for themselves

For this I agree. I actually have calculated safe working levels, by the suggestion of other members, by figuring out case capacity by using bullet length, case length, and subtracting the difference of bullet nose to discover case/powder space. Turns out I am actually much safer at working oal than book stated min oal for an XTP bullet while fully passing plunk. And am doing so by nearly .030". That's a huge difference in comparison.

Considering these findings, your thoughts?

You missed my point. You're discussing volume inside the cartridge case, under the bullet, as created by the bullet seating. I'm discussing the room for the Max OAL as created by how the chamber and barrel are cut. It's the "freebore" between the chamber and where the rifling start that allows the bullet to safely protrude into that space. The greater the freebore, the longer your OAL can be without causing problems.

Here's a cartoon that tries to depict how the exact same cartridge might fit different gun maker's barrels...


Of course, it's just a joke, but you get the point. Max OAL is determined by 1) how much empty space is cut into the barrel, and 2) how your specific bullet fills that space. And no one here knows the answer because you have the barrel and you have the bullet.

When you were a kid, did you ever try to jump a curb on your bicycle? If you rolled your wheel up against the curb, then it was almost impossible! However, if you backed up 3 feet and gave yourself a "running head start" then jumping the exact same curb was easy. Well, the same thing is going on with the bullet and the rifling. If the bullet is right up against the rifling Chamber Pressure (the thing we are always thinking about) will rise dramatically. However, if we can back the bullet away from the rifling, then the bullet will have a much easier time of it. That's why we need to understand the clearances BEFORE proceeding. That is, make our decisions based on hard knowledge (measurements) and not wild guesses.

Remember: In reloading, everything we do is to control Chamber Pressure.

Hope this helps.

 

[rfwobbly]

When pressure testing is done to publish load data, actual pistols/firearms are rarely used. Instead, "universal barrel fixtures" that accommodate multiple caliber barrels are used which are single action that do not feed from the magazine.

So OAL/COL listed on published load data simply means that was the cartridge length used for pressure testing that day for the particular test barrel. But using this length does not ensure finished rounds will fit our pistol barrels nor reliably feed from magazines.

If you are loading for revolvers, you can use the listed OAL but more often, you will use the OAL that will allow roll crimp into the crimp groove unless you are using taper crimp.

But if you are loading for semi-auto pistols that must feed and chamber from the magazines, we must first determine the Max OAL allowed by the barrel then the Working OAL that will reliably feed and chamber from the magazine and this is the cartridge length we use for conducting initial powder work up. (And if the Working OAL, or rather bullet seating depth, is shorter than published, we can consider reducing the start/max charges by .2-.3 gr to compensate, depending on the difference in bullet seating depth, calculations for which we already addressed in previous posts.

This is what a laboratory test barrel looks like...


As you can see it's a single-shot hunk of steel weighing in at about 50 lbs. Since the gun used in the Load Manual doesn't look like the one in your holster, the cartridge you reload won't look exactly like the cartridge in the manual. You'll always have to tweak the data in the manual to get it to work in your gun.

Hope this helps.

 

[CurryCornDog]

LiveLife did an excellent job of breaking it down. But guys seem to really "get" the point with graphics. So I'll sprinkle some on.



There are 2 main components to Chamber Pressure: 1) amount of powder, and 2) the volume it's confined to. If you're going to publish a book saying "this load is safe in your gun" then you had better report both the amount of powder and the OAL (which is the easiest way to describe volume under the bullet). In reloading, Chamber Pressure is our primary (ie. main, No.1, basic) concern because we don't want the gun to blow up and kill us. The experiments that make up the book then, must report the weight of the powder and the OAL.

But in all auto pistol cartridges, useable OAL is a range, not a single point. The Lab that did the experiments is NOT saying "this is the only OAL will work" or "it's the perfect OAL and you should use no other". And yet in each one of these treads someone always speaks up and says "Just use the OAL listed in the manual. That's the best OAL." The book never said that.

Here's a modern parable to illustrate: If you write that your child learned to swim in 3 feet of water, does that mean that ALL swimming pools have to be emptied / filled to the 3 foot level before ANY child can learn to swim? No! There's a wide range of water levels that can be used. You reported 3 feet, but that statement is not a suggested level for the rest of the world.



You missed my point. You're discussing volume inside the cartridge case, under the bullet, as created by the bullet seating. I'm discussing the room for the Max OAL as created by how the chamber and barrel are cut. It's the "freebore" between the chamber and where the rifling start that allows the bullet to safely protrude into that space. The greater the freebore, the longer your OAL can be without causing problems.

Here's a cartoon that tries to depict how the exact same cartridge might fit different gun maker's barrels...
View attachment 1139367

Of course, it's just a joke, but you get the point. Max OAL is determined by 1) how much empty space is cut into the barrel, and 2) how your specific bullet fills that space. And no one here knows the answer because you have the barrel and you have the bullet.

When you were a kid, did you ever try to jump a curb on your bicycle? If you rolled your wheel up against the curb, then it was almost impossible! However, if you backed up 3 feet and gave yourself a "running head start" then jumping the exact same curb was easy. Well, the same thing is going on with the bullet and the rifling. If the bullet is right up against the rifling Chamber Pressure (the thing we are always thinking about) will rise dramatically. However, if we can back the bullet away from the rifling, then the bullet will have a much easier time of it. That's why we need to understand the clearances BEFORE proceeding. That is, make our decisions based on hard knowledge (measurements) and not wild guesses.

Remember: In reloading, everything we do is to control Chamber Pressure.

Hope this helps.

I believe I have a grasp on both things, but please correct me if I am wrong after my thought process here.

OAL must be observed, of course. And to get that, one must make sure the bullet isn't jamming into the rifling upon chambering. If I understand correctly, that is what plunk testing is for.

Now, since my chamber seems on the small side like a CZ (big CZ fan here, so good to know i will be dealing with this in a lot of future calibers lol), and considering my OAL is sitting slightly under suggested minimum OAL in all of my reloading manuals (1.060 is Min. 1.057 is my actual), I also have to be careful in considering how much case volume I have remaining to ensure I can still load safely.

The closest bullet I could compare my bullet to in a book was the 124 gr. Hornady XTP. By all accounts, they are very similar in dimensions. All except bullet length. The average XTP length I could find ranged everywhere from ~.573-.579. The longest bullet I could find in my two batches of RMR Nukes was .547.

Since I must seat below minimum OAL with this RMR Nuke, that 3 hundredths in bullet length more than makes up for the 3 thousandths difference in OA length by keeping case volume from compressing the powder or causing undue stress on the gun with excess pressure.

If this is incorrect, I am all ears and welcome all criticism from anybody. At least from my math and logic, this load will check out and be safe to work up. Will I try to go for major PF with it? Hell no. But I am pretty sure I can make a working load for both a stockpiling load and for an IDPA match load.

EDIT: I must also add that thanks to Mr. LiveLife, I have concluded that if I were to load to 1.057", my setback and final OAL with Blazer Brass would actually end up being ~1.0555" after chambering the round. Still well within safe pressures, but must also be observed. A .0015" setback has been a consistent number for setback when chambering dummies. I could also load to 1.0585" to get me to that 1.057" after setback, but I am neither skilled enough to move 5 ten-thousandths, nor is my press able to be that precise from round to round. Perhaps researching the accurizing of my all american 8 press is in order, if that slight of a movement js even possible. I'm guessing no, as spring-back in brass and differences in range brass is a factor as well. Unless of course I sort by headstamp. That's all for another day. For now I want the rounds to go boom and to go boom safely. The rest will come with time, practice, and learning skills.

 

[LiveLife]

I believe I have a grasp on both things, but please correct me if I am wrong after my thought process here.

How about I make things a bit simpler (For a change)?

After you determine Max and Working OAL for your barrel/pistol/magazine, if OAL/bullet seating depth is fairly deep, just reference more/most conservative load data for your INITIAL powder work up to adjust start/max charges (Instead of complicated calculations/pondering) as you can always go higher on subsequent powder work up/range trips.

And if slide doesn't cycle reliably with adjusted start charge, keep increasing charge by .2 gr until you have reliable slide cycling.

Then keep increasing powder charges by .2 gr until you can see accuracy trend. (Since many faster burning than W231/HP-38 have around/less than .5 gr range for start/max charges, you may have to use .1 gr increment.)

When you identify powder charge that consistently produce smallest groups on repeated range trips (As we all have good/bad range days), you likely have identified "accuracy node" for that particular bullet/powder/barrel combination. If accuracy/group size you are seeing is acceptable to you, you can stop there. But if you want to venture out to check if you can squeeze out bit more accuracy, if your "accuracy node" charge is not at max published charge, you can test incrementally shorter OAL by .005" to see if group size decreases. If it does, use shorter OAL. If not, use longer OAL.

LiveLife ... For now I want the rounds to go boom and to go boom safely

To me, for general purpose range blasting ammo that just need to go bang and punch holes on paper, bullet setback of several thousands is OK, perhaps even for your IDPA match loads, depending on your competitive level.

I have concluded that if I were to load to 1.057", my setback and final OAL with Blazer Brass would actually end up being ~1.0555" after chambering the round. Still well within safe pressures, but must also be observed. A .0015" setback has been a consistent number for setback when chambering dummies. I could also load to 1.0585" to get me to that 1.057" after setback

But if your match shooting requires greater level of accuracy (In terms of precision), then you should work towards eliminating bullet setback variable of your rounds by using deeper bullet seating depth for greater neck tension from thicker case wall further down the case neck, using different headstamp brass that doesn't produce bullet setback, and/or using larger sized bullets like .356" Zero jacketed bullets.

 

[rfwobbly]

First of all... you not only need to match the bullet weight, but also the construction. These are the 2 major contributors to Chamber Pressure in bullets.

Remember: In reloading, everything we do is to control Chamber Pressure.

1) Weight So if you are loading 124gr bullets, then look for an example of exactly the same weight in your manual. Compare 124gr to 124gr. Compare 147gr to 147gr. (The only exception to this is if your weight is unlisted. Say you have a 140gr... then you use the next heavier data, or 147gr data. Or another situation,135gr is popular now. 135gr is exactly halfway between 124 and 147gr, so you can simply split the difference. Eg. if 124gr shows 3.8gr and 147gr shows 3.4gr, then 135gr uses ~3.6gr.)
2) Construction So if you are loading Lead bullets then use only Lead data; if you are using jacketed bullets, then only use the data from other jacketed bullets. If you are using Plated, then you need to consult that manufacturer's web page. Some thinly plated bullets load with Lead data; some thickly plated bullets load with Jacketed data.
3) Starting Load If you do not have the EXACT SAME bullet the manual tested with, then you MUST begin at the Starting Load and work up in small increments, advisedly over a chrono. This is why if you are shooting Hornady bullets, then I highly advise the data in the Hornady Manual. If you are shooting bullets from XYZ and they don't publish a manual, then you should be using an excellent general manual, like the Lyman Manual, in conjunction with Rules 1 & 2 above + using the Starting Load.

If I understand correctly, that is what plunk testing is for.

• If you really want to know if you are close to the rifling, then you must plunk and spin. Plunk may allow the bullet to touch, but Spin will get caught and give you valid feedback. So although a lot of people call it "Plunk", to be really accurate, I insist on "Plunk & Spin".
• However, Plunk & Spin only tells you that the bullet is not touching the rifling. That is OK, but it only reports Pass/Fail information. But what I want is a hard measurement. I want to know "by how much did I pass ?" So if you are counting on passing by a fixed amount, then you need a better method.

All the best

 

[CurryCornDog]

How about I make things a bit simpler (For a change)?

After you determine Max and Working OAL for your barrel/pistol/magazine, if OAL/bullet seating depth is fairly deep, just reference more/most conservative load data for your INITIAL powder work up to adjust start/max charges (Instead of complicated calculations/pondering) as you can always go higher on subsequent powder work up/range trips.

And if slide doesn't cycle reliably with adjusted start charge, keep increasing charge by .2 gr until you have reliable slide cycling.

Then keep increasing powder charges by .2 gr until you can see accuracy trend. (Since many faster burning than W231/HP-38 have around/less than .5 gr range for start/max charges, you may have to use .1 gr increment.)

When you identify powder charge that consistently produce smallest groups on repeated range trips (As we all have good/bad range days), you likely have identified "accuracy node" for that particular bullet/powder/barrel combination. If accuracy/group size you are seeing is acceptable to you, you can stop there. But if you want to venture out to check if you can squeeze out bit more accuracy, if your "accuracy node" charge is not at max published charge, you can test incrementally shorter OAL by .005" to see if group size decreases. If it does, use shorter OAL. If not, use longer OAL.


To me, for general purpose range blasting ammo that just need to go bang and punch holes on paper, bullet setback of several thousands is OK, perhaps even for your IDPA match loads, depending on your competitive level.


But if your match shooting requires greater level of accuracy (In terms of precision), then you should work towards eliminating bullet setback variable of your rounds by using deeper bullet seating depth for greater neck tension from thicker case wall further down the case neck, using different headstamp brass that doesn't produce bullet setback, and/or using larger .356" sized Zero jacketed bullets.

Yep! All noted, and definitely is my plan for workup. Just responding to our friend rfwobbly here on one aspect of OAL. As for setback, I will find/use better brass in time to eliminate that variable. I am big on finding all kinks in a given system and working them out one by one. Finding out what is acceptable, what is not, what must be eliminated, what can be controlled, etc.

I'm a broadcast/live event video engineer. It's in my nature to test everything to failure and then improve lol.

 

[LiveLife]

It's in my nature to test everything to failure and then improve

When you identify powder charge that consistently produce smallest groups on repeated range trips (As we all have good/bad range days), you likely have identified "accuracy node" for that particular bullet/powder/barrel combination.

That's good. It's good to test/work with measurable repeatable data.

Here's a tip for load development and range testing, which you obviously will get to next - "How do we know when our powder work up loads are accurate?"

Easy, just compare to known reference loads or have known accurate factory ammunition on hand to compare during range tests.

For 9mm, my reference load is 115 gr FMJ/RN bullet loaded with 4.8 gr of W231/HP-38 to around 1.130"-1.135" using .377" taper crimp that is comparable to Winchester/Federal white box in accuracy, if not slightly better. (This reference load will produce 1" groups at 7-10 yards, 2" at 15 yards and 3" at 25 yards on average out of various fullsize pistols)

So when I am conducting powder work up/range test or having a "bad range day" where holes on target are not grouping, I will do comparison shooting with my reference load. If I get similarly poor groups, I deem the shooter to be the fault having a "bad range day". If I get 1"/2"/3" groups at 7-10/15/25 yards, I will blame the new powder work up loads and keep on working up til I identify accuracy node by incrementally increasing powder charge then decreasing OAL/bullet seating depth without exceeding published max charge.

 

[CurryCornDog]

First of all... you not only need to match the bullet weight, but also the construction. These are the 2 major contributors to Chamber Pressure in bullets.

Remember: In reloading, everything we do is to control Chamber Pressure.

1) Weight So if you are loading 124gr bullets, then look for an example of exactly the same weight in your manual. Compare 124gr to 124gr. Compare 147gr to 147gr. (The only exception to this is if your weight is unlisted. Say you have a 140gr... then you use the next heavier data, or 147gr data. Or another situation,135gr is popular now. 135gr is exactly halfway between 124 and 147gr, so you can simply split the difference. Eg. if 124gr shows 3.8gr and 147gr shows 3.4gr, then 135gr uses ~3.6gr.)
2) Construction So if you are loading Lead bullets then use only Lead data; if you are using jacketed bullets, then only use the data from other jacketed bullets. If you are using Plated, then you need to consult that manufacturer's web page. Some thinly plated bullets load with Lead data; some thickly plated bullets load with Jacketed data.
3) Starting Load If you do not have the EXACT SAME bullet the manual tested with, then you MUST begin at the Starting Load and work up in small increments, advisedly over a chrono. This is why if you are shooting Hornady bullets, then I highly advise the data in the Hornady Manual. If you are shooting bullets from XYZ and they don't publish a manual, then you should be using an excellent general manual, like the Lyman Manual, in conjunction with Rules 1 & 2 above + using the Starting Load.



• If you really want to know if you are close to the rifling, then you must plunk and spin. Plunk may allow the bullet to touch, but Spin will get caught and give you valid feedback. So although a lot of people call it "Plunk", to be really accurate, I insist on "Plunk & Spin".
• However, Plunk & Spin only tells you that the bullet is not touching the rifling. That is OK, but it only reports Pass/Fail information. But what I want is a hard measurement. I want to know "by how much did I pass ?" So if you are counting on passing by a fixed amount, then you need a better method.

All the best

...yes, I know this. That is why I chose to use the xtp as a start point. I feel a lot of this is being repeated. Repetition is good, but to what gain at this point?

-Same weight: 124 to 124
-same construction: jacketed hp
-Starting Load will be a couple tenths under Min just to be safe from start, and adding .1-.2 at a time from there.

All of these points have been thoroughly covered and accounted for. Again, only difference is bullet length. Per your words, "Remember: In reloading, everything we do is to control Chamber Pressure".

*Shorter bullet length in same sized COAL will create less pressure than a longer bullet. Am I wrong?*

^For the life of me, I can't see how that would be incorrect as the case volume would net to a larger size, thus less pressures developed in the case.

-As for plunk and spin, I thought I've been very clear that I have tested for plunk, spin, and ability to freely drop from the chamber when flipped over. Perhaps not, but I know for a fact i didnt only note that in the initial post.

I do not mean to sound harsh, as I'm grateful for any and all feedback. However it seems as though a lot of what I have already said is glossed over and repeated as if I didn't already state that I have done those things. I'm new to this, yes, but i am not completely stupid lol.

Then again, I'm sure there have been some people not as thorough from the start of their reloading hobby-career causing less than desirable outcomes in the past due to oversight, so I kind of get the badgering.