bullet seating depth

[foxpig]

Ok so tried the loading a bullet to find rifling technique today. Or finding the lands is it ?

anyway. The o.a.l was 2.747..

This is way over the max cartridge length of 2.710for a 243win...

So my question is in load development. Would you go down to 2.710 or 2.700 to be safe. Or what should I do. Even at 2.747 they still fit in the mag and cycle.

Bit of guidence please bays..

[1967spud]

what bullet type? what bullet weight?

[jcampbellsmith]

Questions, more questions. Factory or custom chamber? 1:10 twist or something faster? Regards JCS

[foxpig]

Nosler 80gr bt factory 1:10

[jcampbellsmith]

Nosler 80gr bt factory 1:10

Don't worry about the lands, just seat these bullets at an OAL that gives a good grip on the bullet. You could be anywhere from 50-150 thou off the lands. Work up your powder in steps of say 0.4 gr. Once you feel you have a good powder weight, retry it and bracket the powder +-0.2gr. Once you are happy with the powder weight, try tweaking the seating -8 thou, -4 thou, 0 +4 thou and +8 thou from where you started. Sometimes it all comes together, other times it doesnt'. If it's not working, try another powder.

Regards JCS

[foxpig]

Thanks for that. These bullets are quite long so I could seat them at max oal and there's plenty to grip.

[Andrew]

Don't worry about the lands, just seat these bullets at an OAL that gives a good grip on the bullet. You could be anywhere from 50-150 thou off the lands. Work up your powder in steps of say 0.4 gr. Once you feel you have a good powder weight, retry it and bracket the powder +-0.2gr. Once you are happy with the powder weight, try tweaking the seating -8 thou, -4 thou, 0 +4 thou and +8 thou from where you started. Sometimes it all comes together, other times it doesnt'. If it's not working, try another powder.

Regards JCS

Good advice. I start with the base of the bullet at the base of the neck and work outward. I seldom go far.~Andrew

[DaveT]

If I can start on or close to the lands (especially if it still fits the mag) then thats where I start my COL for load development ....but I do start charges conservatively given the extra potential startup pressure.

 

Conversely the extra effective cartridge capacity allows you some more 'headroom' re max loads.

 

If the bullet is a closely aligned with the rifling as it starts down the barrel then I believe that this has to make sense regarding accuracy (IMHO) .... I can't see that a deliberate 'jump' where it can be avoided or minimised would have any positive accuracy benefits other than it minimises startup pressures....... The only proof of course is 'does it group' and any rule of thumb is prone to be disproved!

[DaveT]

If I can start on or close to the lands (especially if it still fits the mag) then thats where I start my COL for load development ....but I do start charges conservatively given the extra potential startup pressure.

 

Conversely the extra effective cartridge capacity allows you some more 'headroom' re max loads.

 

If the bullet is a closely aligned with the rifling as it starts down the barrel then I believe that this has to make sense regarding accuracy (IMHO) .... I can't see that a deliberate 'jump' where it can be avoided or minimised would have any positive accuracy benefits other than it minimises startup pressures....... The only proof of course is 'does it group' and any rule of thumb is prone to be disproved!

[foxpig]

If I can start on or close to the lands (especially if it still fits the mag) then thats where I start my COL for load development ....but I do start charges conservatively given the extra potential startup pressure.

 

Conversely the extra effective cartridge capacity allows you some more 'headroom' re max loads.

 

If the bullet is a closely aligned with the rifling as it starts down the barrel then I believe that this has to make sense regarding accuracy (IMHO) .... I can't see that a deliberate 'jump' where it can be avoided or minimised would have any positive accuracy benefits other than it minimises startup pressures....... The only proof of course is 'does it group' and any rule of thumb is prone to be disproved!

so if i go up to my max col then this should in theory be as accurate as im going to get the bullet????

at the moment im seating them at 2.645 and they are grouping,but the bullet is a hell of a way into the case neck and very tight in the case neck.

i was thinking of going somewhere near 2.700-2.710 to be nearer rifling and make it alittle easier for the bullet to come out.

at 2.710 the max col for the 243 the bottom of the bullet is still below the case neck..

 

sorry if it sounds like we're not getting anywhere chaps, im alittle simple, and very much appreciate the help. i just like things to be right and bang on.

[onehole]

Thought I would jump in here,,,,2.645??,,,,,,,,,,just load em at 2.737 which is 10 thou off your measured touching lands figure,,,,,,,,start your loads half way between min and max with a powder recommended for that weight head ,,,,make up half a dozen loads going up a max of half grain at a time,,preferably less than this,,,,do not exceed maximum recommendation!!! in fact you will find a good load way before that I expect,,,,,take care,,,,feel free to give me a call if you like[pm me for number} ,,,not being rude but sounds like your new to all this,,,COL by the way is not best way to assess accurately where your bullet actually is.Yeah take care,,cheers Onehole.

[foxing2night]

Thought I would jump in here,,,,2.645??,,,,,,,,,,just load em at 2.737 which is 10 thou off your measured touching lands figure,,,,,,,,start your loads half way between min and max with a powder recommended for that weight head ,,,,make up half a dozen loads going up a max of half grain at a time,,preferably less than this,,,,do not exceed maximum recommendation!!! in fact you will find a good load way before that I expect,,,,,take care,,,,feel free to give me a call if you like[pm me for number} ,,,not being rude but sounds like your new to all this,,,COL by the way is not best way to assess accurately where your bullet actually is.Yeah take care,,cheers Onehole.

Best advice given +1 on that,,,

[Brillo]

I thought I'd drop this one in the mix even if the calibre I'm going to refer to is a .308.

My gun is a Sako TRG-22 and the COAL to the lands, with SMK 155's (#2155) is an average of 2.886". If I load to this the base of the bullet is only just in the case neck by about 10 thou. I know some shooters who run loads at this but I decided to not take any chances when I developed my loads and started with 0.020" off the lands and up to 0.070". Using a very structured load development method I found my rifle shoots the most consistent groups at 0.030" off the lands with all the powders and charge weights I used in my tests and will feed from the mag at this length.

My 6.5x47 shoots best with the bullet ogive just kissing the rifling!

One Sako shooting buddy has found his rifle shoots best at 0.020" and another with the COAL at 2.800, which would be a staggering 0.086" off the lands on my gun.

I think the key thing to recognise is that all rifles are different even within the same make and calibre. No two Sako's shoot the same as I found out with the over-pressure experience I had using H4895.

 

HTH

[Andrew]

I used to fuss over the distance from the lands for decades and gave it up. I load for maximum neck tension to begin with (seated to min OAL) and then work outward. It has worked very well for me. In practice, you might end up in exactly the same place with regard to seating depth, but the foundational benefit of pull-weight is maximized from the start and requires no extra tool purchases or chamber measurements. Seat to min OAL and begin load development. JMHO ~Andrew

[DaveT]

so if i go up to my max col then this should in theory be as accurate as im going to get the bullet????

at the moment im seating them at 2.645 and they are grouping,but the bullet is a hell of a way into the case neck and very tight in the case neck.

i was thinking of going somewhere near 2.700-2.710 to be nearer rifling and make it alittle easier for the bullet to come out.

at 2.710 the max col for the 243 the bottom of the bullet is still below the case neck..

 

sorry if it sounds like we're not getting anywhere chaps, im alittle simple, and very much appreciate the help. i just like things to be right and bang on.

If we ignore the potential deal-breaker about whether or not a given cartridge length will feed from a magazine then my logic for starting just barely on the rifling is this....

 

1) It will most probably produce good accuracy.... it does in my 308 win, 260 Rem, 6mm SLr and 338 lap mag in any event..... a bit of reading will highlight which bullet types are most jump tolerant if you don't want to start on the riflings.

 

2) If it doesn't group at that length then you only have one direction to go in (unless you are prepared to JAM the bullet which I don't) ... IE a little further away from the lands rather than wondering if you need to go longer or shorter to find accuracy.

 

3) If it does group then you know where the bullet wants to sit in the future as your throat erodes from usage.

 

You also mention high neck tension as do others ... I prefer & recommend light tension as I do not then need to worry about it contributing to high pressure if I am loading onto the lands.... if .001 or .002 thou neck tension holds the bullet sufficient for function then I am happy.... you won't get much say in that measurement if using standard dies though!

 

If your bullet is seated a long way into the cartridge (as you mention) then whatever actual level of neck tension you are currently using will be magnified somewhat by the amount of bearing surface that the bullet is held by.... again and only in my opinion , you are better off with light tension so avoiding any potential contribution to excessive pressures.... one less thing to worry about in effect.

 

Also I note references to COL being a suspect measure...... I use a bullet comparator to measure cartridge length off of the bullet ogive and do not measure the case head to bullet tip via calipers .... the latter measurement will always vary wildly due to variations in bullet length at the tip end.

 

Its very hard to give definitive answers in a forum context as there are always more variables than can easily be conveyed in a short post ......and no advice given above (mine included) is wholly right or wrong.... different practices can all arrive at the same / right result.

 

If you are new to reloading then its best to absorb all the process methods and their pros & cons .... preferably aided by someone actually on- hand with actual experience to steer you safely.

 

Good luck.

[foxpig]

brilliant, all very good info,

ive found the powder charge that the bullets like so thats one thing off the list ( yey!)

ive found the bullets that the barrel likes ( yey)

just alittle tinkering with the bullet seating and i reckon im there,..

my only concern was that my rifling was further than i was aloud to seat the bullet, but it sounds like alittle jump is fine/sometimes better( rifle dependant)

i have a buddy who is an ace reloader and has thirty years under his belt, he said this rifle is the fussiest hes ever come accross.thing is hes been in scotland stalking for two weeks so ive had to go it alone abit, thanks for all the reasurance and guidence everyone.

 

went out afew night ago and bagged a few charlies on my own homeloads some at ranges id dreamed about, to do this with my own ammo is a great feeling, like when im sea fishing, making my own leads rigs and digging my own bait. you cant beat it.

just want to pull the groups in to the best the rifle can,then its down to me... im on 14 charlies with 1 miss so far with this rifle, so im probably not going to gain much by doing all this, but everything i can do i will,

thabks again chaps your all very helpful

cheers...

[sonic]

Ok so tried the loading a bullet to find rifling technique today. Or finding the lands is it ?

anyway. The o.a.l was 2.747..

This is way over the max cartridge length of 2.710for a 243win...

So my question is in load development. Would you go down to 2.710 or 2.700 to be safe. Or what should I do. Even at 2.747 they still fit in the mag and cycle.

Bit of guidence please bays..

reading this would I be wrong to assume (it being the mother of you no what's) that you have callipers of some sort but no comparator. I was discussing the load a sized case bullet just seated method with a friend with far more experience than me. And was told to size a case then with dremel cut the neck down to the shoulder clean up the cut. Then do the same thing again and look carefully at the bullet. on the first (uncut case) the rifling was clearly visible on the cut case you could just see where it had touched. He said that as the rifling deformed the bullet you got a false reading. When I measured the two the cut case was shorter so I take off .020" this is my max length. its best to measure a few times just to make sure drill the primer pocket out so you can push the bullet back out.

the minimum length is the one set in stone. max length is more flexible. Bench rest etc many shoot loads jammed into the lands but this is not practical for use where you need to unload (foxing etc) as it can leave the bullet in the lands.

BUT if you take your safe 20 thou jump load and seat into the lands you could end up with dangerous pressures.

saami spec of 2.710" max length is so all factory or reloads will fit in any magazine loaded rifle.

All your concerned with is will it fit yours.