Does seating depth matter for load development? 

Interesting test John, I have a problem comparing seating depth performance (accuracy) with only one round per depth. I think a minimum of 3 shots each depth so that one can see the potential precision of each group between the seating depths. Just me, and I know there are many ways to do comparisons. Thanks for sharing.

It is significant to notice that the point of impact changed significantly as the barrel heated up and/or the shooter grew more tired. Two factors that sorts the men from the boys in F class shooting.

Nice test John, I will also note that the speed stat from the SM is all of 11 SD. Knowing that the speed was slowing with the seating depth, the fact that the SD is still only 11 shows a very forgiving recipe all in all.

This make so much sense. Thank you.

Sounds like a test I need to do in my load workups so I can quit obsessing over that 2-3 thou seating depth. I'm glad you showed those clamtainers! A new thing to buy and try! .... So much work ahead.... 🤔😉😀👍👍

I think it's hard to make a great barrel shoot bad, especially with good bullets that it likes. Awesome demonstration!

As always thanks for such wonderful content. Question though, with all the discussion I've been hearing lately about all the things that don't matter for load development, it's becoming more and more difficult to say with any conviction what a solid development and reloading process should look like. What have you found in your experience matters?

Hi John! From my recent loads I found that with lower pressures and less speed, example: I dropped my speed down 340fps running less powder and now my 140gr nosler does not care where I seat it. Long as -3000 from jam and to short as 180k from jam. It just wants to group. So I am with you on this test. Also fun fact, my ES went down to 2fps from 16fps. 2510fps av 140gr nosler RDF 6.5mmCM using s365 Solchem Powder

I really enjoy all of your videos. I just wanted to say I think most of us are watching these on a smart TV with no option to comment. We can "like + Subscribe" but thats it. RU-vid should realize this in their algorithm

Thanks for the info!

Very nice. Just wondering which process comes first, finding the right load or seating depth? How do you know when to start playing with seating depth, as in how do you settle on a load?

Thanks as always John, Set some of my 6.5 C's at 30 off the lands, and got great results, sub.250 but many one wholes, what's funny is Hornady's 6.5 C's ELD-X are 65 off and shoot .50 groups, really surprised at how good boxed ammo shoots now days. Am reloading the same seeds, but with H 4350

What an eye opener! Thank you for posting, John! - Alex

Was hoping you’d circle back on this. Great recap!

John nice test! What I have found just like others mentioned below, is if we are mag feeding obviously we have to stay within the mag well length and try different ones inside that measurement. What I have found in when speaking with my gunsmith that chamgers or reams my barrel. I may not be saying it correctly because I don't know how reaming a barrel is done. But he tells me about a parallel throat or freebore before the lands Vs what you may find in a factory non custom barrel that is a funnel shape before the lands. So I have found in a factory style barrel the closer you are to jam or at jam the accuracy improves over further back. But with my custom barrels with the Parallel chamber I seat 100-200 from jam and have excellent results. And this of course is using the same bullet, powder and powder capacity. Something to also mention is loading the case and seating the bullet where you have a higher case powder capacity like a lightly compress load, not crushing powder and seating the bullet in further. I have found single digit SD and less dramatic ES from this method. But if you seat the bullet futher out closer to jam. I would start seeing an increase in the ES and SD. Just my 2 cents.

I would think if you settled on the number 5 length you would be in pretty good shape. Thank you for all you do and share with us.

Thank you

Now this is pretty awesome to see, I’ve done extensive testing on seating depth with different manufacturers projectiles and some have wide nodes and some well have stupidly narrow nodes so this could be the case, but you know what it shows a huge picture that at least the powder node you are using for the given projectile is working extremely well which finding is half the battle. I commend you on sharing this John love your channel and what you do with it and congrats on the last day at SWN too massive achievement considering any battles but what you did was commendable 👍🏻

Thanks for sharing. I listen to the hornady podcast kinda pretty much saying same thing. Kinda was confused as a new shooter/reloader

cool test john, I would also think the bullets ogive has a lot to do with the seating sensitivity. Some bullets i’ve fired went from 1 MOA to .25 MOA in 0.090 difference.

I've actually tested this method with my previous load development and will confirm with behalf of John that this does work. This was also before I watched John's video on it and just thought "what a coincidence". Mind you, I did this without a chronograph and developed a load within 30 rounds that shot a 0.71 MOA at 220 yards. This was not for benchrest or F-Class shooting, only hunting purposes. I tested the load 2 weeks later to confirm and it ahot right on the money.

1 shot is spare to conclude much, typically would like to see 3 same depth to gauge any kind of consistency with barrel cooling between each set of 3. Would take longer but may show more reaI information the more shots with same depth is better for evaluating. Everyone has to draw their own size sample group that they are comfortable with. If 1 is yours, my hat is off to you. Thanks for sharing 👍.

I was an anti AR 308 shooter until I met the crew of CMMG in a Lake Ozark Bar. I agreed to try one in 2009. well I bought a complete Lower for $249.00 and commenced to building lowers, I am taking it to the range tomorrow to test some handloads. I still don't need another but if I did it would be a Cmmg.

Good info john

Enjoy the content! I am looking at building an f-class rig and doing my own improved cartridge. Just for fun and enjoy learning how to shoot better!

Thank for videos u put out

Great video, can you please tell me where you got the clear plastic storage boxes that your ammunition is in, thanks in advance.

it matters for both head space AND powder compression (or even just powder free space within the cartridge)

Seating depth is important for those of us "hunters" who have to shoot at magazine length, maximum :) I usually start there and then fine tune, going in, in .005" increments... seems to me that different bullets are more or less forgiving to depth, verses rifle/ load/ powder, but I'd love to see you do a similar test!

What I notice from the pattern is at first the shots were going int a straight line as you decreased the depth, then it got very erratic towards the end and the shots were more random.

Plot the elevation vs seating depth in Excel, it there is a trend, it will show up there. Staring too long at a cluttered target will make you imagine things that are not there. I did a very similar test, but only looked at velocity. There was a very strong linear trend to slow down as the jump increases. At long range, this velocity difference is enough to account for an elevation trend on the target.

Awesome test John! Thanks again. I see the annular ring on the bullets, did it help?

if this trend follows more than 1 shot, id be interested. definitely hope you continue to do this testing.

I was working on a 243 AI shooting 70 gr Dierras with WIN 760. I tried various loads in increments of .03 of a grain. It was almost there but wouldn't quite repeat groupings. Almost gave up and decided to seat the bullets .002 deeper. The reloading gods were with me. Instant magic.

Seating depth is the second most important measurement in Benchrest i wonder why it doesnt matter in F-Class?

Where did you get that pod lock style lever to replace the round knob for the arbor press?

Good content for some sort of testing on a new barrel and 600 yard club matches

I'd love to see a ladder test, three or five shots per load, done twice (ie repeated with the same load configuration). I think you'd be surprised the degree to which the shooter influences the test.

Interesting to see these nodes stack up and then the potential to tune the node with a tuner for a finer adjustment. Ive always started 20 thou off and backed off 5 thou at a time. Some bullets it seems to help, some not so much.

Oh my… you have yourself a very stable load there! It took that seat depth variance, ate it for lunch, and spat out a fine group regardless of what you believe about the significance of seat depth. If I were you I would be plum pleased with this result. A 20rd group is not insignificant.

Thanks John. I am new to reloading and have searched the internet extensively for information on load development. Being a retired engineer, I am intrigued with the latest from Hornady and Winning in the Wind on the need for more rounds to make a group (sample size) be representative of the "population" statistics/dispersion. What this says is that your test is statistically invalid; you would need a larger sample size for each seating depth and then compare the means of the groups and test for significant difference between them. I am not throwing stones here! I know you have extensive experience and success in load development and shooting. As a newbie and with the component shortages we are experiencing, I'm trying to "get it right" with as few rounds/groups as possible. What "rules of thumb" do you have that rate the controllable variables in order of importance. At this point after fixing brass (fire formed, trimmed and shoulder sized by 2k) and a good primer, my list from most to least significant goes: 1) pick bullet type and weight, 2) find powder type, 3) work up safe charge weight, 4) adjust seating depth. The last item 4 is somewhat confusing since it begs the question as to what seating depth do you use for the charge weight testing! I have seen vids and info from Nosler/Berger that show VLD bullets behave better at large jumps compared to starting at 20K off lands as many suggest. Maybe Chris Long's OBT and QuickLoad gets you to the starting powder charge and seating depth? Your view/comments would be very much appreciated! Thanks, and keep the videos coming.

What's crazy is that 1 and 20 are an inch apart! What the heck...

Good stuff

Where do you get the plastic shell holders that you have. looks like a good thing.

I’d be curious about data regarding ogive style (tangent, secant, hybrid) and how it affects seating depth sensitivity/node size.

Bullets with hybrid profile are less sensitive to seating depth variations. If you're using hybrids here, this may be a reason you don't see signifficant changes

I ran some ladder tests for my .284W and 6ARC, both on AR platforms. After some unusual circumstances forcing me to test very deep seating depths, I found my best nodes way down-on both. Not the best groups, but the widest nodes and damn close.

I did not build lowers, I built uppers. 2-300 BO, 2-556's 2-223 Wild. and I bought 2 a 22lr and a 300 Bo Bolt action.

Just subscribed!

Morning John. Love this test. I have 2 questions if you dont mind me asking. You mentioned your donuts have been pushed out? How does that process work? 2ndly, what target cam system are you using?

I’ve found that the widest node to be .050-.080 from jam in multiple guns and calibers

Great content John as always. I looks like you are cutting the Tubb ring on you bullets !Would I be correct with what I m seeing? I didn’t know if you or Eric had come to a conclusion with the ring cutter and testing ! I think you guys need to have a beginner F Class course for all of us that are sitting on the Fence !

How do you think it affects pressure with that much of a change in depth

John, do you thing that the same thing would happend with different calibers or non match guns? 6.5 Creed, 6.5 PRC and yours 7-6.5 PRC have tighter measurments standards that regular calibers, if I'm not wrong.

I can't afford a 2k barrel that will be sub moa with everything, so doing a proper seating depth group helps tremendously. I don't get what your test shows or doesn't show other than you got a badass rifle/powder/tip combo to make that little of a difference

Thank you, this is very interesting. Do you ever seat into the lands? I have a theory that neck tension variations might make less of a difference when bullets are pushed into the lands (not enough to "jam" in Cortina-speak but enough that the force needed to start the bullet moving is signifcantly affected by engraving forces). Unfortunately I don't have the equipment to test this properly, so it's just a pie in-the-skie theory but would appreciate tour thoughts?

Great content. Who makes those clamshell ammo packs?

where do you buy those plastic round holders??

Did you use tuner, because it probably eliminates the difference that comes from the length variation. Or it would be a good testing idea.

Interesting.

17,18,19,20 - thanks for the good video!!

I enjoy and benefit from observing all of these "seating" test showings on RU-vid, but would really like to see a test preformed by the relation of powder burn rate, pressure increase as seating is deeper, finally in conjunction of bullet ogive. With a knowledgeable and factual formula for this to all having the intention of 2 in 1 hole would benefit a great deal. So; is there any know formula for pressure increase by seating depth, burn rate, bullet ogive out there? I'm all ears and eyes for this one. Thanks for the videos.

New hand loader, I liked the video. My question is how does seating depth effect velocity, if at all?

My seating depth requirements are that it must fit in the magazine and feed correctly. Very simple but it's not for everyone.

I was so worried as I have a Panda 284 with a barrel having .5 inch freebore. Did some testing at 5.840 CBTO and am shooting half MoA consistently at 800 meters.

What does it do to the Chamber Pressures? The deeper Bullet must of raised the pressures! Chamber Pressures is the Critical concern here!

My biggest problem is finding a barrel for an ar that is accurate. Always seem to find at least.07 jump. Tried multiple powders multiple projectiles can never get under 1.15 group

Like your arbor press. Silly question - what are the cartridge boxes your using ? Excellent video ! If I don’t have access to a long shooting location, limited to 100 yards - is testing like this evening meaningful ?

John how far were you shooting? 1000 yards? and were do you get those clear ammo boxes? Thanks.

I literally just did one today. Closer to lands, horrible. As we got further away from the lands it was much better

Whats that software you used to draw the final chart with?

Hi John. Love the videos. Well done for SWN. An off-topic question, please: I want to re-barrel my 6.5CM (308 Bolt Face) to .284 Shehane. What barrel length and twist do you recommend? And is my plan feasible? Many thanks. Greeting from Chris, South Africa.

I’m happy that I reload knowing that my round will hit the end of a beer can at 100 yards, then hit a pie plate at 500. All knowledge gleaned from reading Lee’s 2nd edition book The mystery of “ controlled” explosion inside of a tuning fork barrel. Read his book

you mentioned donuts being pushed out. What is your method to accomplish this

A takeaway is that 6 and 14 are closest to aim point and the same distance from the extremes. Harmonics…

Any idea if your es/SD changed and how much?

Would be interesting to do the exact same test again but shooting them out of order.

I think that custom rifles have wider nodes than factory rifles. Do you remember John if this is true when you were shooting the ruger ?

Can you provide information on the cartridge storage packs? Thanks 😎

Where do you get the clear plastic ammo clamshells?

Bryan litz says .015” off and beyond makes little to no difference with hybrids.

if it was me I would look at the seating depths for shots 3-6 and 17-20,,,

thats one hell of a gunsmith, whats your free-bore

I think it would be interesting if you repeated this experiement to help prove whether any trends you might see are real or just luck of the draw. Shot 9, 10, and 11 have similar vertical dispersion as you noted, but shots 7, 8, and 12 (immediately before and after this potential node) are in the opposite corner as shot 9. With only 20 thousandths difference in seating depth between 8 and 12 that would be quite the narrow node if it actually existed. I'd be very surprised if the same test shot a second time (same charges and seating depth) gave the same potential nodes, because these results appear far more random than anything else. A couple small clusters that could be perceived as potential nodes is something that you'd see in a random dataset anyways, and if it's not a repeatable result then there's not much point in following those small random clusters.

Really interesting test. The results just look like a random distribution in a group rather than clusters of close shots at adjacent seating depths. It would need to be tried multiple times to be statistically correct of course. Will you shoot it again?

Where are those plastic ammo blister packs available at?

17,18,19, and 20 look to be petty tight as well.

Like and comment. Glad youtube suggested this.

I enjoy your videos, this one, not so much. 😊 1 powder charge 2 primers type 3 primer seating 4 Brass trim ..Fire forming, Annealing Etc. etc. etc. etc. so on and so on. You do all of these thing as best you can. “That’s good enough. Skip the seat depth test” ??? You can say it doesn’t make a lot of difference in your rifle, but not every rifle will react the same. It could be a significant factor just like all the other steps that were taken. Just not as significant in your rifle. If a person goes through a good load development and skips the seating depth. Yep! That’s the person I want as my competition. Everyone do a seating depth test. Do the 100 steps to create a load. Correction do 101 steps.

I just tried something a little crazy. My 308 reloads were at maximum 2.355" from OTCB. So I loaded some up for a friend of mine (308 with a max 2.25" OTCB). I shot the 2.19" 168gr Hornady 41.5 Varget with my own gun and the accuracy was pretty good (half MOA at 100 yards). I originally seated the bullets out to 2.35". I've seen on this channel and another that from the maximum seated out you should back off .006" seating in to ~.016" per increment.

I question tangent bullets but definitely secant bullets just my opinion

Hmm...

If seating depth doesn't matter for small groups in F-Class terms what does?

You need to redo the test with only shot 6 and 13 loads and see how they score over 20 rounds. ;)

What do you mean the donuts have been pushed out? Thanks

Yes. The answer is yes

How did you push out the donuts?

On very high end rifle like the one used in this test, I guess seating depth may not be as relevant like on a factory rifle.

Seating depth is obvious, but what I want to know is how the new PRC designs with their much longer throats or leads affect accuracy compared to the old 7mm rem mag for example. Since the bearing surface of the bullet is much more exposed on the PRC and can be supported by the throat, does this lend itself to greater accuracy and alignment of the bullet with the bore? On the 7mm rem mag, almost no part of the bearing surface of the bullet is sticking out of the case on the 162 grain eldx for example. Its almost all ogive sticking out. As the bullet contacts the lands, does the PRC have better support on the back of the bullet therefore better alignment? Or does is it the case that is actually supporting the back of the bullet on the 7 mag, therefore adequate alignment? High BC bullets (and higher twist rates) seem to have much lower mechanical accuracy (short range) than the bullets with shorter ogives and a longer bearing surface and less nose cantilevered out into the barrel which must remain perfectly centered or your accuracy is screwed.

I reread your transcript and still can’t quite figure out what you were talking about when you we’re talking about a situation where you would not have to worry about throat erosion .