What would be your approach?

[LocoGringo]

I'm prepping some ammo for a "bucket list" 3-gun match in 2017. I'm going to use the 69 SMK in Lake City brass with CCI 41 primers and Reloader 15 powder. The barrel maker of the barrel I use says basically, if you can't find a recipe with those components around 24.5 grains of the powder, your barrel is defective. Someone who uses the exact same barrel as me discovered his load at 24.8 grains of powder. I can't find the "book max" of this (not even on Alliant's web page, but a load of 25.5 is listed), but what I'm looking for is a solid, consistent, reliable load that is 1 MOA accurate. It's not a NRA match winning load that I'm after. I want a round that hits hard for .223/5.56 and is solid 1 MOA accurate. It might have to flip steel spinner targets at 100 yards or so.

To develop the load, how would you go about it? I've been flipping between 2 thoughts: 1) is to start at 24.4 grains and work up to 25.0 grains by .2 grain increments (10 rounds each load) or 2) do 24.5, 24.8 and 25.1 grains with 10 rounds for each load. I'm fairly new to reloading although I've been doing it for several years in .308 and 6.8 SPC. I just don't know if .2 or .3 grains difference is enough (or too much) for .223 to show a difference iin accuracy with these components. Any ideas? Also, anyone know "book max" for RL15 and 69 SMK?

 

[Driftertank]

Smaller cases mean smaller tolerances, but I've had good results on my own .223 work ups by doing groups of ten spaced at roughly .25gr intervals (rounding to the 1/10; 23.0, 23.3, 23.5, etc). Found little difference from one group to the next usually, but they were noticeable. I was using Ramshot TAC behind 75bthp. Got my best groups at 23.8, but 23.5 and 24.0 were also pretty good. I figure loading in the middle means I have a bit of leeway for temperature changes or other variances.

 

[KansasSasquatch]

I'm prepping some ammo for a "bucket list" 3-gun match in 2017. I'm going to use the 69 SMK in Lake City brass with CCI 41 primers and Reloader 15 powder. The barrel maker of the barrel I use says basically, if you can't find a recipe with those components around 24.5 grains of the powder, your barrel is defective. Someone who uses the exact same barrel as me discovered his load at 24.8 grains of powder. I can't find the "book max" of this (not even on Alliant's web page, but a load of 25.5 is listed), but what I'm looking for is a solid, consistent, reliable load that is 1 MOA accurate. It's not a NRA match winning load that I'm after. I want a round that hits hard for .223/5.56 and is solid 1 MOA accurate. It might have to flip steel spinner targets at 100 yards or so.

To develop the load, how would you go about it? I've been flipping between 2 thoughts: 1) is to start at 24.4 grains and work up to 25.0 grains by .2 grain increments (10 rounds each load) or 2) do 24.5, 24.8 and 25.1 grains with 10 rounds for each load. I'm fairly new to reloading although I've been doing it for several years in .308 and 6.8 SPC. I just don't know if .2 or .3 grains difference is enough (or too much) for .223 to show a difference iin accuracy with these components. Any ideas? Also, anyone know "book max" for RL15 and 69 SMK?

25.5gr IS Alliant's "book max." Alliant's website only lists max loads. Reduce by 10% to get starting loads. ex: 25.5 x 0.90 = 22.95gr starting load.

 

[LocoGringo]

Ok KSSasquatch, but I noticed that the above load for a 62 grain flat based bullet was only 25.0 grains. I'm confused why a lighter, flat based bullet would have a LOWER max load than the heavier BT bullet by .5 grains. So, why would a 62 grain bullet have a max load of 25.0 and the 69 grain bullet have a max load of 25.5? I'm not trying to argue, just confused why that would be.

Of course, this question is a completely separate issue.

 

[KansasSasquatch]

Ok KSSasquatch, but I noticed that the above load for a 62 grain flat based bullet was only 25.0 grains. I'm confused why a lighter, flat based bullet would have a LOWER max load than the heavier BT bullet by .5 grains. So, why would a 62 grain bullet have a max load of 25.0 and the 69 grain bullet have a max load of 25.5? I'm not trying to argue, just confused why that would be.

Of course, this question is a completely separate issue.

Two reasons that I can see. First off, Alliant used different primers. With the 62gr FMJ they used a CCI400 and with the 69gr Sierra load uses Fed 205M. Secondly, a 62gr FMJ may have a longer bearing surface on the bullet than a "match" grade boat-tail bullet. The longer bearing surface could increase the pressure, leading to a lower charge weight being necessary to keep pressure at safe levels.

But that's just speculation on my part. Calling Alliant may get you concrete answers as to why they came up with those charge weights. Either way, Alliant only lists MAX loads, and I won't advise going over those loads.

Copy and paste from Alliant's website:

WARNING


The information displayed on this site, including ballistic data, was derived from tightly controlled laboratory conditions. This information and data may vary considerably depending on many factors, including the components used, component assembly, the type of firearm used, reloading techniques, safety precautions practiced, etc.

Never mix any two powders regardless of type, brand, or source.
Never substitute any smokeless powder for Black Powder or its substitute.

Alliant Powder expressly disclaims any and all warranties with respect to any and all products sold or distributed by it, the safety or suitability thereof, or the results obtained including, without limitation, any implied warranty of merchantability or fitness for a particular purpose and/or any other warranty. Buyers and users assume all risk, responsibility and liability whatsoever for any and all injuries (including death), losses or damages to persons or property (including consequential damages), arising from the use of any product or data, whether or not occasioned by seller's negligence or based on strict liability or principles of indemnity or contribution. Alliant Powder neither assumes nor authorizes any person to assume for it any liability in connection with the use of any product or data.

The individual accessing this site assumes the risk of safe loading practices.
Failure to do so could result in severe personal injury (or death) and/or property damage.

USE THIS DATA WITH ALLIANT BRAND POWDERS ONLY.

REDUCE RIFLE AND HANDGUN CHARGE WEIGHTS BY 10% TO ESTABLISH A STARTING LOAD.

DO NOT EXCEED THE LOADS DISPLAYED ON THE SITE OR ALLIANT'S RELOADERS GUIDE.

 

[rg1]

Just some added information from an experienced source:
http://www.whiteoakprecision.com/info-reloading.htm
Note the overall length listed is 2.250". Also his mention that a near max load in lighter cases such as RP and LC may be too much in a heavier Federal case. I'd recommend loading same brand cases, after sizing and trimming them I'd weigh the cases and separate out light weight and heavier than normal cases in your lot. Just me, but I'd weigh each powder charge. 2.250" oal works best and is slightly more reliable fed from AR mags. The irregular hollowpoint tips will make the overall length vary but the seated ogive will be the same. Some will measure shorter and a few longer than 2.250" but they will stay below the maximum mag length of 2.260". I load 24.1 grains of Rel 15 with 77 MK's and 24.3 grains with 80 MK's using LC and RP brass and RP 7 1/2 primers. 77 gr.MK's actually use less powder than the heavier 80 gr. MK. The 77 MK protrudes farther inside the case taking up more case volume than the 80 gr which stays in the neck. The 77 gr Sie. MK can be loaded to magazine length while the 80 gr. has to be loaded one at a time into the chamber.

 

[Ifishsum]

I've had three different A2s shoot the best groups with the 69gr SMK at 24.2gr of RE-15, so you might start just a little lower than you planned on. To start with I often use .3 or .4 gr increments, once I find a promising load I will test in smaller increments around it to bracket the sweet spot so I can load in the middle of it. Helps account for small variations in load, temperature, etc.

 

[Sunray]

You don't need CCI 41 primers. Those are just magnum primers.
When a powder maker gives just a max load, you reduce it by 10% for the start load. You have to read the small print.

 

[LocoGringo]

Well, Sunray, it's what I use in my 6.8 SPC, so it's what I've got. It's not about "need", it's about what I have.

I understand you're supposed to reduce max load by 10% and work up, but someone else is loading these for me and I don't want to ask too much of him. I also know that each barrel is an "individual", but someone else who has the same barrel as me (same barrel maker, same specs) has a sweet spot at 24.8 grains. I'm assuming some things here (I also know what happens when you assume), but I think they are reasonable assumptions and as long as I don't get too close to book max, I believe I'm safe. I'll be .4 grain short of book max and it's an excellent quality barrel.

I'm leaning towards the 3 loads starting at 25.5 and increasing by .3 grain increments and ending at 25.1 grains. The manufacturer says if you don't have an accurate load around 24.5 grains of RL15, something's wrong with your barrel (speaking of his barrels) and goes so far as to recommend a COAL of 2.285" (which I'm not going to do). I've got to load for reliability and functionality in any magazine, so I'll go to 2.250".