Interesting slant on load development.

[Big Al]

I sat in on a question and answer session with Callum Ferguson today, the topic was developing loads which is something he does a lot for all his custom rifles. He made a very specific statement which has really got me thinking, it was;

 

"I use powder charge to achieve velocity and seating depth to get accuracy"

 

This pretty much turns the OCW testing I have done completely on its head and goes against the advice I was given here last year that finding the right powder charge has the biggest effect on finding accuracy nodes? In general Callum seemed to favour using a chronograph and then adjusted the charge until he first had the velocity he wanted, from there he would find his accuracy by varying the seating depth by increments of 0.010" at a time and he was not afraid of big jumps into the lands. He was respectfully dismissive of small adjustments in powder charge weight or altering seating depths by small amounts like 0.002"" as he suggested it didn't make enough of a difference to be useful.

 

Callum seemed a very practical type of guy and I found listening to his thoughts very interesting, he certainly seemed to know what he was talking about. That said Im not suggesting he is right and the advice I been given here is wrong, I just thought it might make for an interesting discussion that we might all learn something from.

[triggersqueezer]

when i ran a 204 i did wonder why my accuracy nodes allways seemed slower than everyone else.perhaps this answers the question.

[srvet]

Surely the two are inextricably linked as both affect pressure and therefore presumably velocity. I always viewed powder charge as coarse adjustment and seating depth as fine adjustment. Perhaps I'm wrong ?? I certainly don't profess to know as much as Callum

[Big Al]

Surely the two are inextricably linked as both affect pressure and therefore presumably velocity. I always viewed powder charge as coarse adjustment and seating depth as fine adjustment. Perhaps I'm wrong ?? I certainly don't profess to know as much as Callum

 

I have often wondered why the propellant or the charge amount should have such a big effect on accuracy alone, if indeed it really does?

 

If we choose a CBTO length and then do an OCW test the results of that test could surely differ quite a lot had we changed the CBYO by 0.030" as a nominal figure. Every time we change CBTO then potentially we also change pressures so as you say the two can be closely linked. I remember reading an article in Sporting Rifle recently where Byron Price also describes starting first with a set powder charge and looking for the best nodes using seating depth.

 

It really has me now wondering which is the best way to go? I did this test myself recently and the same charge was used although it was a charge I had established by first doing an OCW test. The different seating depths brought different results but surely considering I went from touching to 0.080" off the lands the pressure and thus velocity must have changed a bit.

 

[gunnery]

Hi Al after saying all that when I had my AI AE MK111 I was loading 308 sierra 155 and Lapau bullets I shot a very

small 5 shot group first time out and very happy with the group has a matter of intrest and being a new rifle I kept pulling the

bullet further out nearer the lands and seating further in the case never affected the group has we know most people will say you need to be in the lands or just 005 of lands for best accuracy but I don't know about that most of my best loads seem to be .020 and .030 of the lands for best results.

[gbal]

Gravatt& Sinclair (Precision Reloading and Shooting) are usually a reliable guide.Here are their observations for best seating depth:

 

22cf .01 to .02 off rifling

6mm just touching to .010 off rifling

larger just touching

 

These are no more than a guide as to where to start-rifles vary individually.

More jump spmetimes work if the above doesn't.

 

.002 might indeed tbe too fine-and pushing the precision of seating depth variation!

 

Always remember that measures of CBTO are comparative-you can compare different bullets,by the same measuring equipment and person,but manufacturing tolerances and individual differnces in sensityivity are very considerable,so person A and person B may well not agree,using their equipment,or even because of their sensitivity. (COAL 2.093 for A and 2.057 for B for the same round would not be unknown...)

 

Varying seating depth does result in more 'space' in the cartridge-the net effect is less velocity and pressure.I may not be large,and there may well be 'tolerance' around a node-as in OCW/ladder tests.

But accurate measures of these are hard to come by.Some think touching the rifling/hard jam into it it has a greater effect - plausibly,but measureably? You are then into transitions( between static friction (neck tension) and kinetic friction (seating depth).....and that is complex indeed. And ogive factors-secant may need slightly less force than tangent,but generally secant are found to be sensitive (fussy) wrt depth......

 

gbal

[Offroad Gary]

Surely callum was only saying what most people do when developing a precision load?

 

1. Work up the charge weight monitoring velocity, looking for low es/sd, and a good group.

2. Tune load by varying seating depth to get the smallest group without increasing es/sd.

 

Whats new in that?

 

I do hope he had a nice time at the deer stalking fair, i know he was looking forward to it..

 

Personally i dont get the ocw method, looking for centre point of group closer to poa than the other groups??? Just doesnt work in my rifles.

[gbal]

Gary,sort of agree....brief desriptors out of context can case mischief.I can't see many reloaders with a set in advance velocity must have,to the extent that a 3 inch group would be acceptable,if it gave the velocity-usually it's a balance acceptable velocity and one of the smaller groups found...?(and not everyone wants max vel anyhow).

 

But the choice of a two or three adjacent groups which showed a close POI (not POA) and decent grouping seems to be motivated by the average powder weight of these three (and they'll only be .2g apart,remember) suggesting a stable node-ie powder variation of .2 either way still gives good performance-allowing a bit of tolerance in reloading technique/measures.The barrel likes this weight of powder,+/- .2g.

It may well be that most OCW/ladders etc are just too extensive-is anyone going to settle for 3g less than book max,unless there just isn't anything faster that is acceptable?(unless they want a mild load,of course.) Going over book max isn't recommendable,but generally there is a decent load within say,1.5 g,and that's where to focus....Of course if you get pressure at 1g lower than max,down you must go....

 

100 fps velocity seldom makes/breaks a cartridge in real world field performance.If it worries you,get a better potential cartridge from the start.....run a little light,not over the red line...

 

Then for seating depth tuning,see what usually works for that calibre,maybe even rifle.bullet and try that for starters (remembering measurement/rifle variation).

The general point is,don't labour away at unlikely combinations,it's discouraging and uninformative-reinventing the buckled wheel!

 

When you get your sweet load,check it with 10 shots,then if still good ,enjoy another 10... you are done.

Use rifle for what you intended it. Vargberg combinations won't be significantly better-though you might have done well to start with known big hitters. :-)

 

gbal

[Ronin]

Precisely that point Gary.

 

Find a powder charge they gets you the velocity you want and if you're lucky groups reasonably well.

 

Then play with the seating depth of that charge.

 

 

I dont do load development any other way - you've got to separate the two stages.

 

 

Incidentally its also what Gerald Shultz recommends (he who owns GS Custom bullets)

[Murph]

Surely callum was only saying what most people do when developing a precision load?

1. Work up the charge weight monitoring velocity, looking for low es/sd, and a good group.

2. Tune load by varying seating depth to get the smallest group without increasing es/sd.

Whats new in that?

I do hope he had a nice time at the deer stalking fair, i know he was looking forward to it..

Personally i dont get the ocw method, looking for centre point of group closer to poa than the other groups??? Just doesnt work in my rifles.

Plus 1 on this. I've always worked up the powder to get good velocity ,es and good groups. Then I will mess about with length. But not too much usually.

[snow white]

When you first start how do you know how ?far to put bullet in I know you come back of the lands but who is saying you are right.I have got tool that tells me how far the lands are from the bolt face but then it is working out how far to seat the head.I can not see how you can get a powder charge right by just putting head in case and trying it.their are to many variations to much powder not enough powder. head in to far or not in enough.I pick a tried powder charge then muck about with seating the head it works for me four rounds out of a factory barrel touching at hundred yards.

[Offroad Gary]

When you first start how do you know how ?far to put bullet in I know you come back of the lands but who is saying you are right.I have got tool that tells me how far the lands are from the bolt face but then it is working out how far to seat the head.I can not see how you can get a powder charge right by just putting head in case and trying it.their are to many variations to much powder not enough powder. head in to far or not in enough.I pick a tried powder charge then muck about with seating the head it works for me four rounds out of a factory barrel touching at hundred yards.

Surely what youre describing there is the same. Stage 1 and 2. Just that someone else has performed stage 1?

[snow white]

What I am trying to get at who said that was the wright amount of powder in the first place.

[gbal]

snow white: ok,the capacity of the case is known,and measureable.The maximum load of any powder can be worked out-you just have to accept what the powder maker says,because they know how to do this,and have done many tests. So have lots of reloaders.So we have a good idea of the upper limits.OCW/ladder tests are just rechecks on this for individual rilfes-though there can be no pressure testing for the amateur reloader.Experience suggests a good load-probably within a grain or so of the max loads,but just go up in .2 towards max load and the better groups indicate the better powder weights for that barrel,though it will be no surprise if it's similar to some others. That's stage 1.

Then you vary seating depth with that same powder load,finding the best grouping depth.Stage 2.

That's i,though you would need rather more than four shots to check it- almost any load can give three shots touching sometimes,only a good load will give 3 shots touching nearly every time.So five or so such groups strongly suggest a reliably good load.

Essentially,each shooter knows from all the already done work that the likely good load(S) are in a quite small range of powder weight,for a given widely tested powder,and he just tries increasing weight from that range to see what suits his rifle,and more or less then the same process with seating depth.

Done carefully,many will do load development in under 30 rounds,with say ten more checking ,consistent shots.

What is nearly right-if you like the recipe-is generally known at the start-fine tuning is the game,to that rifles individual taste.( checking always,of course,no unexpected pressure signs are found).

But the general recipe has been sorted,no one is starting from scratch,if they are savvy.

 

gbal

[Offroad Gary]

Ok, try this.

 

1. Increase powder charge, .3gn incriments up to pressure signs. Stop. Pick worst group.

2. Mess around with seating depth to obtain best group (and es/sd) with the load that gave the worst group.

 

Is that going to find your optimum load?

[snow white]

How do you know how far to seat head when doing load development if the head is far in to far or out to surely you will not get accurate placement so you cannot tell if the round suits your gun.like with air gun you keep trying till you get pellets to suit gun.can you see what I am getting at.when I first brought my rifle I joined the gun club I shot some factory rounds then we rezised the the lad did load development out is book we load some rounds of different head seatings of I went shot four different targets took them back he said they want putting at this length.I tried them spot on.stuck with them for that gun still spot on.got a new gun as you problem gather.do not go to gun club now the bloke who runs it is a funny bugger so working on my own reading loads of books.thank for your response

[Big Al]

Surely callum was only saying what most people do when developing a precision load?

 

1. Work up the charge weight monitoring velocity, looking for low es/sd, and a good group.

2. Tune load by varying seating depth to get the smallest group without increasing es/sd.

 

Whats new in that?

 

I do hope he had a nice time at the deer stalking fair, i know he was looking forward to it..

 

Personally i dont get the ocw method, looking for centre point of group closer to poa than the other groups??? Just doesnt work in my rifles.

 

I wasn't suggesting this was new Gary and neither was Callum, he just stated how he did his load development when asked.

 

Im fairly new to reloading myself and the advice I received when asking here was to do an OCW test with the bullet seated 10 thou off and then once I found the most accurate charge weight I could then fine tune the seating depth in 2 thou increments if needed. As others have alluded here that could and has ended up for me with an accurate load but that is well down on velocity.

 

I also asked once which made the biggest difference to accuracy, charge weight or seating depth, the consensus of those who replied said charge weight.

[Offroad Gary]

How do you know how far to seat head when doing load development if the head is far in to far or out to surely you will not get accurate placement so you cannot tell if the round suits your gun.like with air gun you keep trying till you get pellets to suit gun.can you see what I am getting at.when I first brought my rifle I joined the gun club I shot some factory rounds then we rezised the the lad did load development out is book we load some rounds of different head seatings of I went shot four different targets took them back he said they want putting at this length.I tried them spot on.stuck with them for that gun still spot on.got a new gun as you problem gather.do not go to gun club now the bloke who runs it is a funny bugger so working on my own reading loads of books.thank for your response

I reloaded for blaser r93's for years, probably the most unfussy rifle you can get. Never measured the col, just made them to fit in the mag which enforces a restriction to keep you well back from the lands. I bought a rem 700 25-06 and as a consequence bought a comparator. Sold the rem, bought an r93 barrel in 25-06 and made some rounds as long as i could and measured them with respect to the chamber. They were 0.186 off. That rifle shot very very well.

 

With turnbolts i always start .020" off and 1gn below book max. An initial 3x3 shot test max-1, max-.5 and max gets me out hunting, load development starts after that. Problem is knowing which book to take your max from, or with wildcats that dont appear in the books!

 

Enjoy!

[Ronin]

I do quite a bit of load development / testing for customers.

 

I measure the OAL (from base of case to bullet touching lands at Ogive) then measure the space available within the magazine (if the overall length (bullet tip to base of case) exceeds the space then you CANNOT load to the lands.

 

If this is the case I start with a loaded round with the bullet seated .020" less than the available mag space and work from there - using powder charge variations and THEN adjust the seat depth with the most accurate load.

 

If there isn't a restriction on space, I'll seat the bullet .020" off the lands and again make different batches of powder charges in .5 grain increments and once the most accurate load is found I will adjust seat depth in .010" (+/-) until the most accurate seat depth is found.

 

I may continue with adjusting the powder charge in .3g increment from there and again adjust the seat depth but thats rare.

[gbal]

Snow white,Your comparison with an air rifle and trying out different pellets is a basic similarity-the closest for a cartridge rifle is buying different commercial loaded ammo,and seeing which shoots best in your rifle.

In both cases ,you have no 'control' over whatever is affecting performance-you can't alter the pellet/bullet,for example-though you can use different weights of bullet-but you have to take what you get.

Handloading is different in that you can have some control-you can still buy different bullets,of course,but can't trim a bit of lead off them (or shouldn't!),BUT you can control and vary systematically two of the main other contributors to accuracy and velocity-the powder load (type and weight)which contributes more than anything else to velocity,and a bit to accuracy;and bullet seating depth which fine tunes accuracy,for that rillfe.(broad ballpark is that powder load might get to about .5 moa,and fine tuning might trim .1moa off that,to give best accuracy).

Of course you are right-since both contribute to accuracy,how do you know where to begin...well,as the other posts suggest,there is a lot of experience on this and around .02 off the rifling is usually reasonably close (remember that depth is not going to contribute a lot anyhow).So use that.

Then load powder-guided by books/other safe loads- in small increases (lets take .3g) with the bullets all seated the same (.02off),and test fire for velocity and accuracy,going up until the signs of pressure are seen,or until you are happy with the velocity (best with a chrono,but book values are reasonably close,with same length barrel etc as book-individual rilfes of course vary a little.)

Chose a promising powder load that groups well.Then gradually change(vary) the seating depth with that load,and check accuracy-it might tighten up a little. Settle on the best. Load a good few at that and test fire a few groups.

Comparisons can be helpful,but be careful not to push too far-as with airgun pellets. In cf reloading,you are following a general recipe,then fine tuning the serving....sort of-I mean that there will be plenty guidance for how long to cook your meat,so that it is edible (even rare or well done),so you try that,and alter if need be,the 'fine tune' with the herbs etc once you know the best cooking time/temperature. Sort of the same with cooking/reloading,get the main variable (time and temp/powder weight).sorted,fine tune (herbs/seating).Of course,taste isn't accuracy,but the general approach is much the same-it is systematic try and test (taste!) til you get what you want. All safely,of course,and of course meat varies etc-a bit).

You have control of the variables,and can record their effects,so you can home in on the best for you.Bon appetite!

Quite a lot of shooters simply don't fine tune seating depth (or much else,if they buy factory ammo),and get performance that is at least 'good enough' for their use-eg many stalkers will load to just long enough to fit the magazine-a whole lot more critical for them than optimum seating depth-which might be too long to fit in the magazine,and they simply don't need that elusive ultimate .1 moa,as much as they want a back up shot.Also remember some rifles best won't be .5 moa.(the recipe won't work for leather,even if it does beef a treat!)

And you don't need to be NIgella :-)

 

gbal

 

 

 

 

taste) with

[onehole]

"Secrets of the Houston Warehouse",,,look it up for those that have not,,,,,,,these guys have just got to have known what they are doing,,it is stated that the best[.22 interestingly] and groups in the .0,s came more from a "jammed in" position and anything loaded off jam then powder load had to be adjusted to bring in the vertical and horizontal. I will make a bold statement in saying that within reason no matter where you are with regard to distance from lands you will more than likely find a powder load to suit and equally a powder load to suit position off lands,,,,same thing just the other way round,,,two ways of doing it.Personally I like to be close to lands(single load) this maximises potential powder load and has to be best potential for best accuracy. Admittedly these guys probably shot mostly pure custom/bench rifles but the same effects must surely be evidenced in the rifles that we all shoot.The article also labours the need for a perfect reloading regime and attention to detail ,,,so true,,,,O

[gbal]

Houston is 'must do reading' for afficionados,but expect a few surprises:

 

22 was the most accurate overall,then 6mm(mainly PPCs) then 30(8),a modest third.

 

Powder: used Culver only,not scales. .1 or .2 ( even more) didn't matter.When powder run out,just bought another can from the store. Same bullets (Rem 22 and 6 bench rest)

 

All screamers (sub .1) were shot with bullets touching the lands,at least.

 

Velocity-didn't know,didn't care-if it's the same hole,speed going through doesn't make any difference.

 

Hmmmm.if you feel your life work threatened,it's all the memories of one man,and there were no doubt lots of nearly screamers shot,some perhaps with terrific consistency of fps and SD and seating depths.

It's all target groups,mostly at 100y.

 

And sorry-Houston is shut.

 

gbal