Safety ladders with CFE223 and 123gr. SST's

[Heywood]

Well Heywood, I am soooo hesitant to comment on your pics and data when there are so many people on this forum with about a billion times more experience than me, but I guess I'll take a stab at it,

Primers 3,5, and 10 look like they are just starting to crater, and primers 2,3,6, and 7 are looking a little flat for my comfort level. Assuming those are CCI450 primers, you can always try a slightly thinner cupped primer (eg. federal 205M) and see how they look......I'd definitely stay with a magnum primer though....

Looking at your data, it could be that your velocity is starting to plateau after 32.6, if the extreme spread and standard deviation are getting bigger, thats a sure sign you're heading into a bad place. I think Hornady does list a max load of 31.7gn for the 129gn bullets, so you're not off into crazy land yet :-)

I would guess that 32.5 might be a reasonable max load for now. To me, the trouble with CFE and LVR is that they are so mellow that Its easy to get in to a slightly overpressure load that is going to beat your bolt to failure without knowing it.

Thanks for your time and input. The pictures aren't the best so I can see what you are saying. The light plays tricks though. As the only one with any difference to the others is number 4. But you can't see it in the pictures.

[Savage Shooter]

For really helping sort out accuracy and the right OCW load (which for the unfamiliar is a "modified" ladder test developed by Dan Newberry - click here for an overview http://optimalchargeweight.embarqspace.com/ and here http://optimalchargeweight.embarqspa...ons/4529817134 for more details of the procedure), I have found the software from Jeffrey Block's OnTarget Data systems http://ontargetshooting.com/tds/ to be very helpful, especially if you want accurate group measurements and comparisons of your different groups' point of impact relative to point of aim. Some of us (try to) measure things beyond the practical level of significant digits, but for those who want to measure and compare things as accurately as our budgets and equipment allow, I have found this to be a cost effective software for helping analyze OCW and group size data.

[LRRPF52]

This thread hit at the right time for me. They way I work up a load is to run 1 charge of each weight just to look at the primers and see were the edge is. So from a 30 to 32 ladder, I will load up 30 30.5 31 31.5 and 32. I shoot these to get a baseline. I then go back and drop off maybe the 30 and 30.5 but run 5 rounds each of the 31 31.3 31.6 and 31.9. I will take the low and high accuracy nodes and go to .2 of a grain both above and below those charges. So if the 31.3 and 31.9 are the low and high, the next charge ladder will be 31.1 31.3 31.5, & 31.7 31.9 32.1. Run all of these over the CED chronograph while watching for primer issues.

By this time I have a real good idea of where the load will be. I will take the fastest and accurate load. Even if that means I settle on the low accuracy node. I'll sacrifice speed for accuracy.

Please reconsider loading in no more than .3gr increments. CFE is very forgiving, but you might want to think about the individual traits of your chamber, and slowly build pressure. With a linear curve assumed, you will be adding about 3,100psi with each .5gr increment. There is a lot of opportunity for things to spike on you if your chamber has a slightly shorter throat. The rule of thumb that I use for hand-loading when determining charge weight increments is 1% of case capacity, so with a ~34gr case capacity of the Grendel, I use no larger than .3gr increments.

The primers are not a reliable method for gauging excessive pressures either.

[rickOshay]

Heywood - I may have missed it skimming, but what is the max COAL in your chamber for the 123 SST.

[kmon]

Agree with the 1% steps, have been doing that for years. Lot of things effect chamber pressure and Primers though often talked about can be an indication of pressure but they are not a reliable one. By the time "Classic" primer indications appear a load will be sometimes be over pressure, sometimes way over pressure. I will look at the primer but look at the case more, is it getting any shiny spots on the case head, measure the case for expansion at the webb. Stress fractures are real and not just on jet aircraft (remember the Concord) where we hear most about it.

The only firearms I look very closely at the primer for pressure indications is the TC Contenders, there when you are getting to max load for your Contender. On the Contenders with the centerfire and rimfire fireing pins and holes you will see the primer begin to faintly flow into the rimfire hole when you are at the pressure to stop at and back off a tenth or two.

When shooting ladder tests I will use different colored sharpies to mark the bullets out toward the tip, sharpies have a little corrosive chemicals so don't mark far enough up the bullet to contact the lands. The colored bullet will transfer the color mark to the target, making it easier to see which bullet made which hole. This works on white paper, not so much so on other colors or card board.

[Heywood]

Heywood - I may have missed it skimming, but what is the max COAL in your chamber for the 123 SST.

Yes sir, it was buried in there. 2.276. I still have some room left, I can't rememer exacrtly how much off the top of my head as I used a comparator.

[Heywood]

For really helping sort out accuracy and the right OCW load (which for the unfamiliar is a "modified" ladder test developed by Dan Newberry - click here for an overview http://optimalchargeweight.embarqspace.com/ and here http://optimalchargeweight.embarqspa...ons/4529817134 for more details of the procedure), I have found the software from Jeffrey Block's OnTarget Data systems http://ontargetshooting.com/tds/ to be very helpful, especially if you want accurate group measurements and comparisons of your different groups' point of impact relative to point of aim. Some of us (try to) measure things beyond the practical level of significant digits, but for those who want to measure and compare things as accurately as our budgets and equipment allow, I have found this to be a cost effective software for helping analyze OCW and group size data.

Thank you for the heads up. I will give it some attention this weekend.

[Heywood]

For those that are wondering what kind of real world longevity you might get, I have been loading 31.2gr of CFE under the 123gr A-MAX since late 2012, when I did my first pressure ladder with CFE/123gr A-MAX.

The pressures are very low with 31.2gr, but still give me 2500fps. 31.1gr gives me 2489fps, and 31.4gr gives me 2520fps, again from a 16" little carbine.

This discussion is another great example of how small increments equal large jumps in pressure with a case that holds 34-35gr of water.

.3gr of charge weight increase increases the pressure substantially. I would consider loading in .2gr increments as you pass 31.0gr just to help dial-in an accuracy node.

Thanks for the info. I would be very happy with an accurate load at around 2500-2550 fps.

[LRRPF52]

To be totally honest, we could spend all day following benchrest techniques for OCW, or just pick a load that is safe, mass-produce it, and go out and practice with that load.

The by far biggest variable in all of this is the wobbly, beating heart, expanding-contracting lungs, attention-deficit disorder shooter. Load up a decent charge weight, get out and start blasting. It takes a lot of work to be able to consistently hold even 1 MOA for me. Sure, I can cherry-pick my groups and only show the best ones, then claim what a great shooter I am, but the reality is that I get rusty when I don't practice, so what's the shortest route for me to get out and shoot in volume with clear performance goals?

Crank out a box or two of hand loads using consistent, quality components, or grab a case of factory ammo and go to the range.

[Heywood]

To be totally honest, we could spend all day following benchrest techniques for OCW, or just pick a load that is safe, mass-produce it, and go out and practice with that load.

The by far biggest variable in all of this is the wobbly, beating heart, expanding-contracting lungs, attention-deficit disorder shooter. Load up a decent charge weight, get out and start blasting. It takes a lot of work to be able to consistently hold even 1 MOA for me. Sure, I can cherry-pick my groups and only show the best ones, then claim what a great shooter I am, but the reality is that I get rusty when I don't practice, so what's the shortest route for me to get out and shoot in volume with clear performance goals?

Crank out a box or two of hand loads using consistent, quality components, or grab a case of factory ammo and go to the range.

I hear what you're saying, I do not have any aspirations of making this a bench gun, I actually do not like shooting off a bench at all, it is to me the least fun part of making accurate ammo. I much preferrer shooting from various field positions at known and unknown distance. However, when I can't be out shooting, ide rather spend my time working towards something positive.
Besides, I run through thousands of rounds of 5.56 and 9mm per year so I like to take a different approach with my Grendel.

[LRRPF52]

With that 31.2gr CFE load that I really didn't even do any OCD/OCW development for, a friend of mine who was shooting the Grendel for the first time cleaned a Know Your Limts plate rack with it at 500yds. The little carbine is a consistent 1 MOA AR15, no matter what I really do to it, so I can't complain.

We'll be shooting nothing but field positions in my course next weekend. When you take those positions, then use them in natural terrain, with more steel than you can find in the target area, it becomes a lot of fun.

[Heywood]

I am very bummed that I couldn't make the time to go. I was hoping sometime to be able to take some lessons from someone who knows what this cartridge can do and has real world experience. It's kinda ridiculous really. I have over 240 hrs vacation saved up and I still can't find time for the important things in life.

[Jakal]

[apynckel]

Sry to necromancer this thread, but is anyone running these loads from an AR? I need COAL for mag length seat depth restrictions. Should I just load to 2.260? I am about to start a run of CFE223 under some 123gr SST's myself. Gonna be slingin them from a Shilen 24" barrel.

[Jakal]

I settled on 31.6 grains of CFE223 @ 2.255. Find out how far you can load before jamming the lands. Length should be determined from the chamber, if a long chamber, you may have to stick with mag length.