Stop Chasing the lands - Fine Tuning COAL to find the accuracy node

[@duggydo]

Erik Cortina is a smart fella. Plus, his barndominiums are awesome.

[@ErikCortina]

Thank you. 😊

[@alwaysreloading288]

I thought that was him. I was like damn this dude looks very familiar lol.

[@aubreysteele4466]

@@ErikCortina No-thank you Erik. I'm an old man now and I can't afford a lot of the tools you use, but everything you've advised in your videos that I could do has worked. I have nine high-powered hunting-type rifles. I own from .22-250 up to .30-378 Weatherby. None of them have the expensive target-type scopes pro shooters use, but every single one of them will group three shots consistently into 1/2" or less at one hundred yards using Leupold hunting scopes. The .22-250 will do less than .2" if I can hold it steady. Keep up the great work!

[@dgreenapple]

I think the methodology is great and given all the factors that distort a group, it's close to perfect. However, the most important factors it ignores are the human shooting the gun and the environmental factors at the moment of the shot. With the same hunting (not precision bench) rifle and the same custom ammo, I've shot 0.58 MOA, 0.36 MOA and 0.17 MOA on different days at the range. Every time I was trying my best. You just can't underestimate the impact of those two factors... :)

[@OvertonWindex]

Riiiight... that's why you do this test... What are you getting at? That's literally why you test in this way.

[@swampysanta5445]

barrel temps effects groups a lot my cheap guns will shoot 1.5 inch groups after 5 rounds they settle to 3/4 inch

[@sarahconner9433]

Accuracy below 0.75 moa are getting close to random fluctuations in random elements.... Your 0.17 moa day is definitely awesome!!!

[@StuninRub]

@@swampysanta5445 Your gun is the most accurate when it is cold bore. The barrel does not shoot better after it warms up, it shoots worst. The person is the thing that warms up.

[@user-un5my5bw4j]

​@zhidazhou3113 exactly, i do not know where that guy got the idea that a rifle shoots better when it gets warm that is so not true. Thats the only thing I do not like about Williamsport's benchrest rules which is we shoot 10shot record strings. I wish we did 5 shot strings like IBS. Plus excessive heat is hard on the throat

[@ErikCortina]

Good video.

[@paulvenn4447]

Hope the PRS match went we mate!

[@PracticallySquared1]

Eric is a great guy. Been on KZbin for years and he's the first person that got me to subscribe to their patron. His content is so great. Ive tried all of his stuff and have had tremendous success.

[@ramsaycountry1177]

Lol, yes you could safely say Erik has done "some" winning. He's one of the best f-class shooters in the country! I always thought it was " If you're happy and you know it clap your hands clap clap, 👏👏

[@hankbrinlee4677]

I think you're spot on in your interpretation of this methodology as described by Mr. Cortina. Just wish I had the skills to shoot the difference in the increments...😀

[@stariadversesmalum4638]

I’ve been doing this with AR15 loads. Most people I talk to say it’s pointless because I’m limited by the magazine. After countless hours doing it anyways I’m here to say, IT MATTERS! My best being 1.50” group at 100 with a 12” chrome lined barrel shooting 55gr out of a 5.56 barrel 1:7 twist. That without worrying about neck tension or annealing. Adjusting the OAL from rifling gave me a fluctuation of +3 inches until I found the best. I found that what powder you use definitely matters as well. I couldn’t shrink my groups with AR COMP but found I could with CFE 223 which gave me 0.5” groups at 100 yards. Also, I came to the conclusion OAL DOES NOT equal the same results as changing your powder load. More powder = greater velocity than seating shorter.

[@thebigmansoutdoors]

Good video. I watched the video you referenced and found it very interesting and also have spent a fair amount of time reading the Precision Rifle Blog. I do think that there is something to be said about that as I seem to be finding accuracy with longer bullet jumps. Time on the range is my limiting factor at the moment.

[@lanceschul]

I’ve used the Berger method and have even modified the increments but woes great. I’ll try this method too. Like you said, no need to do this until you find the correct powder charge.

[@joevollmer3037]

I used Eric's method on three different rifles 223 , 308 , and 6XC and was impressed with the results.

[@chandlerhorsley1264]

I love seeing the data like this--well done! Very informative. Thank you!

[@maxchalice5625]

Awesome videos thanks! Been waiting all week for this. One of the things that Eric talks about that is a precursor to adjusting your seating depth is having a optimal charge with a low ED & SD. I'm assuming that you had that but I'm curious as to how the seating depth affect it?

[@jacobfranke3138]

Are you by chance adjusting from the standard seating die seating stem to a VLD bullet specific seating stem? Just curious if any runout with the standard die? Also what press is that?

[@Longshothawk]

Erik also stressed finding the consecutive groups that have the same point of impact. I think he would avoid the 2 smallest consecutive groups that hit in different places.

[@ryanbrand3946]

I have found out on my hunting rifles do to the smaller barrel your node is small compared to a target barrel. I go in smaller increments in seating depth to find the nodes.

[@ryridesmotox]

Mkre data points... I feel you on that one. I always load wider testing than I think I'll want. The 1k range is an hour away, I don't want to get back and wish I had more data to gather.

[@johnwilliams-gk1fb]

Any chance you can lay velocities over the group size to see if there are pressure stability nodes correlating?

[@geraldkoch394]

I like watching ur videos, I am a new year and have never reloaded a thing, with that being said ur way to fast, I find hard to keep up but guys that do this all the time can probably keep, thanks for all the videos

[@conservativesniperhunter7439]

You can watch the video as many times as you want to understand everything.

[@chandlerhorsley1264]

did you shoot these over a chronograph? it would be really interesting to see how MV changes with seating depth especially as CBTO is near your measured lands touch length and you go from in the lands to off them.

[@chazt4863]

Very interesting concept and evaluation...Thanks! have you considered shooting this format at 200 or 300 yards to validate your hypothesis?

[@lohikarhu734]

Wow! A LOT of work, sir...and, of course, interesting results. I think that the point of working around that "flat spot" in the waveform gives you a more reliable point to work from, maybe a bit more tolerant of temperature, velocity...but, I'm just a simple "test & measurement" guy ;-)

[@Dwayne7834]

Thanks for sharing great information and video. I always enjoy your videos and Eriks Cortina’s videos and information

[@hbsoldier3]

Been waiting a week for this vid, thank you.

[@michael-cp8vq]

thanks for another great video even as lost as I am with all these numbers I'll get it sooner or later thanks again .

[@hazcat640]

BAR, OK you're using 41.3 grns of powder. As you are changing the seating depth by .045 over the test did you start with a load that would be safe at the shortest COAL and not worry about pressure and velocity changes as the COAL changed?

[@gerritpretorius7898]

Good info video. Wil there be a difference in testing increments of 3 thou for secant vs tangent ogive bullets?

[@jeremys8360]

I’m currently getting .25-.5 moa with a 1993 Remington 700 bdl varmint, Boyd’s thumbhole, 6.5-20 simmons whitetail classic, 2.800, 168 grain SMK, 43 grains of imr 4166, and Im getting cloverleafs at 100 and 150 yards. The jump is over .100. I cannot load the 168 to touch the lands. I don’t understand but it works

[@JimHarmer]

VIDEO IDEA: Could you tell us your process for actually going out and shooting the groups? I'm on a Caldwell "The Rock" rest and rear bag while shooting prone. I think I can only hold about 1/2 minute steady. What's the best setup for extreme steadiness so I can test groups this finely? Thank you!

[@TexasTrained]

Try out a Protektor model #61 & their heavy bags.It made a world of difference in my groups.I had a Caldwell prior to the Protektor stuff.Their bags are awesome too.Its like going from a Model.T to a modern day Cadillac.

[@peterconnan5631]

Very interesting. Something I have been wondering about (but don't currently have the tools to test for) is whether seating into the lands would reduce the effects of varying neck tension?

[@ronzi83]

Hey, I would like to ask you if you did some cooling on barrel or did you wait some time between shoots ?

[@squirrelmaster760710]

If I'm reading this correctly, 2.222" is the bullet touching the lands, and your node starts off with the bullet jammed into the lands approximately 10 thousands of an inch. Is what I'm stating correct?

[@aldredge_saxxon]

I would be more interested in your process if a like projectile was used as Eric used, out of fairness. I think you would have done better on your test. Try that with a Berger VLD Target, you have the equipment. Good video.

[@paulvenn4447]

What's the velocity to CBTO graph look like? Has it got similar dips?

[@SnipeU696]

Love the charting.

[@conservativesniperhunter7439]

Well done , that was very informative.

[@stevenbradley2245]

As always great information

[@contactericjones]

As you seat the bullet deeper and deeper aren't you increasing velocity and pressure possibly degrading your ES and SD?

[@NzSikastalker]

I found that seating deeper reduced velocity in two of my rifles and appeared to reduced pressure. That was from jam back to 0.120" off jam. I don't know if this is normal or not, I'm a novice reloader.

[@403jasper]

sorry for the dumb noobie question, but . . . how is jam neck tension dependent? seems like it would be a fixed distance from bolt face to lands, regardless of how tightly the case neck holds the projectile

[@RetrieverTrainingAlone]

What was the velocity standard deviation like across the range of bullet seating?

[@sarahconner9433]

Excellent question...I believe there is a definite correlation

[@ironbomb6753]

I didnt understand the relationship between the neck tension and the jam dimension. Any help woukd be appreciated. 👍

[@BoltActionReloading]

Check out this video where i cover it in more detail. kzbin.info/www/bejne/qoK2ZGZufJmhkJI

[@DracoOmnia]

Do you use some kind of app or software for measuring your groups?

[@ReelTimeCapt]

Great video and thx. I have one question and that is - With this technique, what is the process to determine the FPS ? Or do you do this for each powder charge you are working with? Thx, FletchMan

[@BoltActionReloading]

Hello Check out this playlist if you want to see the whole process: kzbin.info/aero/PLXl7rMHW73NOH6EKeU70IrjZoiHcYFenq The one you are specifically asking about is the second video I think.

[@ReelTimeCapt]

@@BoltActionReloading - Thank you and that helps. I just bought a RCBS Chargemaster Link to replace my 30 year old manual Lyman 500 and will give this a try! Thx again and keep the Great Videos coming!

[@pawswet9476]

Shouldn’t this be Fine tuning CBTO to find the accuracy node?

[@laronskaare8024]

Wouldn’t you try 2.228 or 2.227. Seems like a result with less variance?

[@timandrews4722]

What if you're reloading a few rifles with the same caliber? Would you want different reloads for the same caliber?

[@anascottwelding1761]

Every barrel fires differently. Even off the same production line.

[@timandrews4722]

@@anascottwelding1761 ya I completely understand. I load 308 and don't want 2 or 3 different loads if I buy more 308 rifles.

[@AvocaSingleTrack]

I found my lands then set my BTOL 0.030" less . I got lucky...getting 1" at 300 yards.

[@michaelbritain5546]

Yep works for me too, and CD size bull at 600 yards, I've never had the patience to chase lands anyway.

[@tonywombolt8786]

Can somebody explain the correlation between neck tension and jam, I assumed jam meant ogive touching rifling but I’m not sure now or what factor neck tension plays...

[@BoltActionReloading]

Did you check out this video? kzbin.info/www/bejne/qoK2ZGZufJmhkJI

[@pawswet9476]

Jam is the difference of two frictions, at a variable location beyond touching the lands. Unless you hold neck tension constant, jam is not a dimension-hence the claim “jam is a function of neck tension”. Jam seems to be a point where the friction between the interference of ogive into lands is equal to the friction of neck tension. With all these variables, jam seems like a *horrible* reference point. Similarly, overall length is also a lousy reference point because of projectile manufacturing variations. But just like mag length limits, you need to know your jam limit so you can avoid it.

[@FlorianReid-c5k]

Thanks!

[@alangriffith5823]

Is their a simple tutorial on creating the Sine Wave graph in EXCEL?

[@jackbuckley4471]

Good info from the talking arm

[@formulajoe2]

I’d be interested in seeing a velocity graph laid over the top of this one!

[@flashgordon5309]

Please repeat the same test and overlay the graphs to validate.

[@sapago4166]

You are always so exacting. Why did you not use the same mandrel that was used to determine jam??

[@BoltActionReloading]

Hello, if you watch the video on finding jam kzbin.info/www/bejne/qoK2ZGZufJmhkJI I explain it better. but the short version is without less neck tension I would just jam the projectile it would never seat deeper.

[@sapago4166]

@@BoltActionReloading once I watched the entire series it ended up not mattering anyway because of where you found a great node.

[@sapago4166]

I absolutely love your channel btw. I was just curious because you determined jam with one mandrel and then used a different mandrel for your loaded rounds

[@BoltActionReloading]

No problem, I am glad you enjoy it. Questions are always welcome, it's how we all learn. I have almost universally had the best luck (sd,es, and groups)with .002" of neck tension (I have a Playlist on this as well) I just couldn't get a good jam number with it. Hopefully that makes sense.

[@sapago4166]

@@BoltActionReloading Makes perfect sense.

[@donaldbrunswick]

If you're happy and you know shoot your groups! :)

[@wheelgun5102]

As I got to this comment and was reading it he said it. Perfect post

[@altruisticscoundrel]

I enjoyed this video even more than I thought I would from last week. Have you tried contacting Erik directly instead of just waiting for him to notice you?

[@PracticallySquared1]

He commented on the last video.

[@adamwagner7105]

Interesting, but to validate your method it'd be interesting (and maybe fun) to recreate the exact same thing. Load the same 16 sets of loads. Shoot it again. See if you get the same sine wave and same results. Or if the sine wave just means you're shooting an average of .450 (or whatever) regardless and that the jump isn't that important. 3-shot groups are hard to discern real value in group size. Unless you're shooting from a mechanical rig, there are too many variables. Good luck. Bad luck. Fatigue. Eye strain. Etc. It's true that once you find your load you might go load 12 more of that load and see if you shoot 4, 3-shot groups if they all consistently stack in that .250 range. I'd say run with that. You obviously can shoot, so was that .800 group a shit load or did you just jerk one out of the group? Hard to believe that .003 seating depth went from nearly your worst group to nearly your best group just on seating depth.

[@TheFlyingPlectrum]

it's just natural variation . He could shoot the same exact(lol) load 16 times and get the same results.

[@sarahconner9433]

Damn bro!! You almost had the makings of a book!.... But the testing at 100 yards is way way way too close!! Had you tested at 200 yards or even better 300 yards you could have definitely eliminated allot of the random error elements!! However I appreciate the large amount of work you did! Thank you... Please in the future think about doing 300 yards tests.. Since your way into the sniper accuracy anyway!!!

[@BoltActionReloading]

Hi Sarah, not everyone can get to 300 yards and this was the way the testing was described by Erik in his videos. Nothing wrong with modifying a process but sometimes you need to follow the directions as they are given or not be surprised when a process doesn't work.

[@sarahconner9433]

@@BoltActionReloading excellent!.... Keep it to the recipe....I agree

[@brianwood1726]

if i remember the only number he uses is seating depth. not coal

[@blackandsmart]

Good work but I am concerned about your conclusion. You put a lot faith in the group at 2223 where one out of three is off and you ended up with .725 MOA. Sure, three shot groups are fast and frugal, and at 100 yds, they're very likely to conceal the true message that resides within your experiment. Five peaks and five valleys of MOA within a 45 thou range, you really trust it? .794 to .253 to .658, you believe that's real? There is nothing wrong with the basic setup of your experiment, but to obtain a trustworthy answer, you have to go much bigger. And repeat it the next week.

[@warpedweirdo]

If you're happy and you know it shoot your groups. Bang bang If you're happy and you know it shoot your groups. Bang bang If you're happy and you know it then your holes will really show it. So if you're happy and you know it shoot your groups. Bang bang Lol

[@DLT704]

Damn slow down talking

[@reece674]

Just a word of advice if he is talking to fast you can literally set custom playback speed on the video settings

[@jamesfarr9225]

On my I phone? Lol!!!

[@jamesfarr9225]

Woo hoo!!! found it!!! Thanks!!!!

[@mikeburrage6048]

Sounds like a lot of math just to move away from that number anyways

[@paulschulz5243]

your talking to fast---slow down

[@Bill-v650]

With this method you haven't avoided chasing the lands though. The node you found was only 0.006" wide. That is approximately 100 rounds worth of firing (source: precisionrifleblog.com/2020/03/24/how-fast-does-a-barrel-wear/ [6-7 "thou" per 100rnd typ.] ). So over over the course of say a 250 rnd PRS match you are well out of that node. Here's some data: precisionrifleblog.com/2020/03/29/bullet-jump-load-development/ precisionrifleblog.com/2020/04/05/bullet-jump-load-development-data/ I didn't reread all of this article that I read previously but iirc the data says you can find a node 0.070-0.110 off the lands and only tweak your seating depth like 3 times or never during the life of the barrel (depending on how flat your node is for that barrel & load).

[@Longshothawk]

My understanding is that Erik's main point is that the bullet will not move out in a 1 to 1 relationship with the lands.

[@ErikCortina]

jondchaffin Thank you. You get it!

[@mab0852]

Erik is following the groups not chasing the lands. His methodology is based on a stable relationship between group size and cartridge length not distance to lands. He's having several short conversations with the rifle about best length for the smallest stable (not necessarily smallest overall) group. His initial jam measuresurement is for stay out purposes only, the testing that follows is to find the original sweet spot in length. He doesn't test again until his rifle complains and his groups open up. Even then he just tests going longer .003 at a time until he reestablishes the good group and never remeasures anything relative to the lands because it's irrelevant.

[@ErikCortina]

Michael Barber Close. I don’t wait for my groups to open up. Keep in mind my node is usually 0.006” wide. So I occasionally test 0.003” longer to see how it performs. If it shoots as good as my current setting, I move forward. If it doesn’t, I stay where I’m at. If groups open up, I waited too long. I just shot a group after shooting 180 rounds this weekend. Group is identical as before I started match, so I won’t move regardless of what the lands did.

[@Bill-v650]

I watched the video referenced, it has no data to support any of it. It all sounds like chasing the lands to me. Check the links I reference, They are saying the same thing, no need to chase the lands find a load and stick with it. However they have data that points to stable loads never occurring with loads that are 20-30 thou or whatever off the lands. When that close in loads are more sensitive to OAL which causes pressure/velocity changes with throat erosion. Further out is an accuracy node with enough jump to be insensitive.

[@dannywarren1549]

It would be easier for the new reloaders... if you guys didn't waffle on and on... and just break it down into a few easy steps.... and then fine tune with all the jargon after... surely it's not that hard for you guys to do... but none of you do it ... why?

[@dahut3614]

Uh oh, Erik is here and he's looking for someone else to publicly ridicule!

[@Russell-1]

A good grasp of statistics would save barrel life by showing the futility of testing in this manner.

[@mattchilders3123]

Well, I'm not a statistician, so I'm going to ask you to develop the answers here. Please, let us know your method and results. We're all here to learn.

[@scottfreeman984]

Can you talk any faster

[@BoltActionReloading]

Hi Scott yes I can. However if I am talking too fast you can turn the speed of the video down to .75 and it will probably help.