Most efficient route to an accurate load.

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Re: Most efficient route to an accurate load.

Post by marksman » 19 Sep 2017, 8:16 am

If you get your best precision from just touching the lands when the throat erodes you will keep needing to adjust your seating depth, playing the game
you will need to be very consistent with your oal as if there is a difference you may touch 7200 psi then not touch 3626 psi = flyers
so what was said to me was a jump of 20 thou or a jam of 20 thou and you wont be playing the game
2)- I will usually jump for testing unless my rifle wont do as well as I would like then try a seating depth test from jam to a big jump to see what it likes
sometimes it is just a touch on the lands but sometimes it wont like anything, time for a big change
3)- I usually try a jump of 10 thou
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Re: Most efficient route to an accurate load.

Post by Stix » 19 Sep 2017, 1:26 pm

Thanks Marksman...!
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Re: Most efficient route to an accurate load.

Post by Gwion » 20 Sep 2017, 8:05 am

To clarify, I only start my load development on the lands. Once a basic charge has been established, I then test looking for best results with a jump. As I have previously stated, I don't jam my bullets so starting on the lands gives me only one direction to experiment in: that is away from the lands.

Many target shooters insist that best accuracy is attained from a 20thou jam, others insist that a 50thou jump allows for variations in seating because that far out a 5thou tolerance has little effect whereas a smaller jump will be more sensitive to seating tolerance.
Hell, this is all so subjective that there are even those that insist that touching the lands is THE most precise method (as in Houston Warehouse Accuracy Project) but these guys seat bullets "long and loose" so that each round adjusts itself onto the lands (a very basic explanation); this is most certainly not suited to hunting rounds but I have had a small experiment with it and my initial results support the theory.

What ever the case, you are always going to "chase the lands" to some extent unless you are in the "new barrel once a season" brigade (or recut chamber regularly).

Just to get even more confusing, there is evidence that too great a jump can cause pressure spikes...... :wtf: :crazy:
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Re: Most efficient route to an accurate load.

Post by marksman » 20 Sep 2017, 9:12 pm

its not really to great a jump that causes pressure spikes its seating your bullet deep, I see this when playing with quickload
as you seat the bullet deeper the internal volume gets smaller and pressure rise's
also I don't think there is anything wrong with an experienced reloader starting load development touching the lands or jammed if that is what they want to do and know what to look for in regards to pressure
and I totally agree "this is all so subjective"
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Re: Most efficient route to an accurate load.

Post by Stix » 20 Sep 2017, 11:42 pm

Thats great info guys...i really appreciate hearing your views & approach...!!!

As for being subjective...definately...!!!

If its of intetest to you guys (no doubt you've heard it), a BR shooter & hunter i know of (& a well respected one at that) says that with a new rifle, you are best to firefom new brass with a 20-30 thou jam...
The theory being that in his experience...
*there is little load data to be gained until the barrel has settled down (lets say hypothetically its 40 rounds).
*jamming 20-30 thou ensures the case is fully supported by the bolt---this forms the brass at the same time as stretching the cases at the front of the case, rather than at the rear (the web where it will fail if continually streched), thus, indirectly gaining brass life while settling down the barrel.

The subsequent brass to be formed will still be accurate enough to hunt with, (obviously being aware that once a round is loaded the best way to remove it is to fire it...! Not something to do on your average spotlighting jaunt, but easier with a varmint/target o/fit)

From there quick load tests with formed brass seated off the lands will give accurate & rapid load results...

After a lifetimes experience i will probably have developed a preference, but may still be somewhat unsure of the ultimate...
I guess its the drive to do our best that drives the curiosity...

Cheers
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Re: Most efficient route to an accurate load.

Post by Chronos » 21 Sep 2017, 7:02 pm

sungazer wrote:It is often needed to jam the bullets as the case shoulder may not touch the chamber. when the firing pin hits the case moves forward taking some of the energy from the firing pin and a misfire occurs. Not such a problem in factory rifles as they usually have much stronger firing pins but can happen. I know from experience it was a s**t of a lesson to learn. It only takes about 4 thou in some rifles.


Factory rifles have much stronger firing pins?

Stronger than what?

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Re: Most efficient route to an accurate load.

Post by Stix » 21 Sep 2017, 7:40 pm

Chronos wrote:
sungazer wrote:It is often needed to jam the bullets as the case shoulder may not touch the chamber. when the firing pin hits the case moves forward taking some of the energy from the firing pin and a misfire occurs. Not such a problem in factory rifles as they usually have much stronger firing pins but can happen. I know from experience it was a s**t of a lesson to learn. It only takes about 4 thou in some rifles.


Factory rifles have much stronger firing pins?

Stronger than what?

Chronos


Well the brass i have is new so the shoulder of case will be well back from chamber...so i guess if i jam the projs as this guy suggests up to .030" the case shouldnt move anywhere...
The dummy rounds i chambered were firm on the bolt close.

I dont know anything about firing pins, & dont have the experience of you guys, but ive never seen a rifle not fire because the firing pin pushed the case too far forward...not saying it doesnt happen, just not seen it myself.

Can i ask you Chronos--i can reach the lands feeding thru the mag...
Given that, where is your suggestion to start with seating depth...?
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Re: Most efficient route to an accurate load.

Post by marksman » 21 Sep 2017, 8:14 pm

jamming is the way to go when fire-forming, when I make 17 ackley hornet or dasher cases I use a false shoulder and jam, the false shoulder is made so that I can just close the bolt for a good head space and the jam is to be sure about it
jamming .030" even .020" will hold the case in place as it fire-forms
I have seen cases that miss fire from being pushed forward, still dent the primer just not enough to fire, usually a second hit will get them firing
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Re: Most efficient route to an accurate load.

Post by Chronos » 21 Sep 2017, 8:38 pm

First firing with new brass is very different to forming factory brass to a wildcat chamber.

I would and have seated to the lands to form 7WSM brass from 300WSM cases but that's because the shoulder needs to be blows forward a mile compared to a first firing a .308 case in a .308 factory chamber on a hunting gun.

Go shoot it mate. There's no need to apply most of this stuff to a factory gun for Varmint shooting

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Re: Most efficient route to an accurate load.

Post by Chronos » 21 Sep 2017, 10:00 pm

sungazer wrote:When I said stronger. I meant that the firing pin hits a lot harder than a lot of target rifle actions.



I think you'll find it's the opposite mate. Target rifles tend to have heavier springs to help reduce lock time.

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Re: Most efficient route to an accurate load.

Post by Stix » 05 Apr 2018, 4:56 pm

I have another question in regard to this subject, that stems from initial load testing & not getting solid repeatable results...

In other threads, im sure ive seen one or more of you guys have mentioned something to the effect of--you will soon know if a bullet/powder combo will shoot in your rifle...
So... How soon do you know--?
the first group...?
and where do you experts start with powder charge...? say its a conventional cartridge, is starting middle of ADI data the way to go...?
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Re: Most efficient route to an accurate load.

Post by marksman » 05 Apr 2018, 5:47 pm

not that I regard myself expert, I don't and learn more all the time, sometimes a real big penny will drop :drinks:

usually I will see a recipe will be going to work by the groups clocking on the targets at different charges,
meaning the groups although different charges will print the group at the same o'clock, say 3 different charges in sequence at 9 o'clock
then I will know that's where to further test in that area of volume, you may be lucky enough to hit a load to try again
that's how I will find the volume, then if needed I may do an OAL test if the volume test looked good enough
I like to put a few fouler's down the tube before testing

I get my start loads from working out what my max will be and taking off 7% then working up to the max at .5 gr for 308-30-06 size and .3gr for 222 size
always checking for pressure

then it is just make the load the same again, just repeat what you have done
a mate got me to do some work on his rifle including load workup, I found a very good load, all he had to do was duplicate it, he changed the seating depth because I had the projectile just kissing the lands where it shot well, I shouldn't have told him, he believes you cant do that with a hunting rifle, it stopped shooting precisely, he complained to me that it would not shoot anymore, I made a few rounds up and met him at the farm and it shot as it did when the load was worked up, he still believes you cant have the projectile kissing the lands in a hunting rifle, his rifle does not shoot, I don't waste my time anymore :violin:
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Re: Most efficient route to an accurate load.

Post by sungazer » 05 Apr 2018, 6:28 pm

My experience has been kissing or lightly touching the lands is not a good area. Your measurement tolerances total may mean you get inconsistent grouping due to inconsistent seating depths. I am either jam them 10 thou or jump them at least 20. The jump, jam thing is really a projectile gun thing. The throats of some rifles may be at different angles than even you think. This can be a bit of a trade secret by some gunsmiths.
As for how much powder first decision is whether you want to shoot them fast or or slow? there are normally a couple of sweet spots in the range. There are some that believe that is a fallacy as well and one velocity is as good as another.
So that was no help go out and give it a go :lol: sorry mate wish I knew the answers
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Re: Most efficient route to an accurate load.

Post by marksman » 06 Apr 2018, 9:14 am

I believe the rifle will tell the truth about what it likes and some like to have the projectile kissing the lands,
I prefer the same as you sungazer for the same reasons, a jump or a jam but if the rifle likes a touch so be it
I also like to pick a powder that will leave as little air gap as can be
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Re: Most efficient route to an accurate load.

Post by Gwion » 06 Apr 2018, 10:15 am

Stix wrote:I have another question in regard to this subject, that stems from initial load testing & not getting solid repeatable results...

In other threads, im sure ive seen one or more of you guys have mentioned something to the effect of--you will soon know if a bullet/powder combo will shoot in your rifle...
So... How soon do you know--?
the first group...?
and where do you experts start with powder charge...? say its a conventional cartridge, is starting middle of ADI data the way to go...?


Again. No expert here but to answer this directly:

I start low because there is a common theory that your most accurate 'node' is likely to be closer to minimum than maximum. I load up 3 rounds in 5 different charges at 0.3gn increments (only loaded 223 & 308 size cartridges so far). This gives me 1.5gn spread, which is (in most bullet/powder combos) most of the way through the charge range in a 223rem cartridge and half way through a 308win size case. I take my time with each shot to avoid user error and look for the best group that has similar group size and pattern at the charges either side of it. All these rounds will be loaded on the lands. If I can't find any acceptable groups then I go back to the drawing board.

I have found that asking specific questions on forums as part of your research can help get the answer you need, which can be very time and money saving.
For instance, when I started loading for my 7-08 I put it out there that I was hoping BM8208 would be good as it would save me using multiple powders and encourage me to buy one powder in bulk but that I was planning on shooting f-class and practicing for possible long range hunting in future so I was after the most reliable and stable powder for the cartridge for fine accuracy. A few experienced shooters in both LR Target and LR Hunting all chimed in that AR2209 had worked best for them and other they knew. Sure enough, I tested both BM8208 and AR2209 and even with initial load testing the AR2209 was better. Of course there was a plethora of "AR2208 is the best", etc. but these guys answered my specific question specifically. Had I just been after a general hunting load, I would have just stuck with BM8208 for convenience and economy of purchasing scale.

As for starting on the lands for load development, it gives you a definite choice of which was to test for seating depth improvements. The best I could get on the lands for my 7-08 was about 0.7-0.5MOA average group, fine for general hunting but not going to cut it for f-class or shooting out past 500yd. I then tested in 5thou increments off the lands, again in 5 lots of 3 round groups. The further I got from the lands the worse things got but I found that 10thou off the lands yielded 0.3moa. I re-confirmed this with 3 lots of 5round groups and am still shooting the same load.

So, to get a hunting load I allow about 30-50 rounds and to get a target load I allow 50-70 rounds but if I don't get anything half decent in the first 15 I go back to the drawing board.

Just on the 'loading to lands' thing. My 223rem loves it. Move off the lands and thing open up on all 3 loads. So much so that on two loads with one bullet, I actually trim the tip of the bullets so that they feed smoothly from my mag as it has far less effect on accuracy/precision of the round than seating to max mag length!
I had one load with 40gn BT Energetics Varmint that used to shoot very nicely when this barrel as in the original Howa action but once it was set back a touch and the chamber touched up to go on the Lefty Zasty action, it wouldn't shoot at all at max mag length and although I can get it shooting by sitting it on the lands it is seated so shallow to achieve this that it is a bit dodgy and a risk of losing bullets and ending up with a mag full of powder, even if I did trim the tips to feed from the mag.... So, I have about 800 of these bullet left! :thumbs down: I'll have to get around to finishing the original project so that I can finally use them all up!


Crap... That ended up a LOT longer than I intended! Hope it makes some sense and is of some use to you. :thumbsup:
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