ES / SD reduction strategies

[Rich4]

I’ve recently decided to follow Keith’s advice re moly coating mainly for barrel maintenance (if there is ever any moly powder in Qld again) and it occurs to me that it may actually help reduce ES via consistent neck grip and possibly more consistent seating depth, now I’ve never tried adjusting neck sizing diameter to change tension, except unintentionally by skim turning necks in a factory chamber.
What do you feel is the largest return on investment for reducing ES ?
Neck tension adjustment?
Bullet pull?
Powder Charge?
Primer selection?
Case selection?
Headspace via Fls? Ie not the one between my ears

[Steve N]

Definitely powder charge. Then primer selection. Instead of case selection I'd include sorting and prep which should take care of variable neck tension and bullet seating etc.
I don't believe moly will assist in reducing extreme spread of velocity variation but yes it does make bullet seating smooooth.

[Gyro]

I’ve recently decided to follow Keith’s advice re moly coating mainly for barrel maintenance (if there is ever any moly powder in Qld again) and it occurs to me that it may actually help reduce ES via consistent neck grip and possibly more consistent seating depth, now I’ve never tried adjusting neck sizing diameter to change tension, except unintentionally by skim turning necks in a factory chamber.
What do you feel is the largest return on investment for reducing ES ?
Neck tension adjustment?
Bullet pull?
Powder Charge?
Primer selection?
Case selection?
Headspace via Fls? Ie not the one between my ears

I'd suggest just bear in mind Rich that shooters are notorious liars.

[Rich4]

That’s very cynical of you, I’m sure that’s not the case at all

[Gyro]

:lol: That’s very cynical of you, I’m sure that’s not the case at all

Alas ......... the top, winning guys who have done the hard yards are obviously the best ones to answer your questions Rich.

Personally I can see ES/SD only having possible significant implications for any 'compensation' that may be happening, but then the theory that gets put forward about that is normally way over-complicated ! And for this a tuner supposedly helps, then the theory is once again stupidly hard ....

[Wal86]

Ive done quite abit of load development on my own 1000y range.. All my testing was done when its nice and frosty under lights at 2am (zero air movement)... I can tell you that low ES/SD and small groups dont always correlate. The paper tells the only story..

Most my IBS1000 yard targets were shot with BIB 187gr flatbase projectiles..

Cheers Alan

[Pommy Chris]

Definitely powder charge. Then primer selection. Instead of case selection I'd include sorting and prep which should take care of variable neck tension and bullet seating etc.
I don't believe moly will assist in reducing extreme spread of velocity variation but yes it does make bullet seating smooooth.

I think Moly can help in this respect and my reasoning is twofold. First 0.1 of a grain more is less with moly coated bullets in other words 0.1 of a grain may give 12 feet per second more velocity for nude bullets, but maybe only 5 feet per second for moly coated. This will all depend on what the load is ie how much powder is in case already and projectile weight etc. Point is any errors loading with moly will make less difference to velocity than non moly coated. Second point is neck tension.. Neck tension does make some difference, but how much difference does it make if the projectile is slippy? Less of course point being here is the necks ability to hold the projectile with differing neck tensions, with moly the differing neck tensions make less difference due to the projectile being slippy.
Chris

[KHGS]

Ive done quite abit of load development on my own 1000y range.. All my testing was done when its nice and frosty under lights at 2am (zero air movement)... I can tell you that low ES/SD and small groups dont always correlate. The paper tells the only story..

Most my IBS1000 yard targets were shot with BIB 187gr flatbase projectiles..

Cheers Alan

This bears out what I have been saying for some time now. I question the validity of low extreme spread, it can't hurt to have it, but it may not be the "holy grail"!!
I also question the addiction to super high BC and ultra heavy for bore diameter bullets for 1000 yds, A lot happens to the stability of these long high BC bullets when they tip over at long range. Wal86's observations and those of a number of 1000 yard benchresters in the US tend to reinforce this. One must keep an open mind!!!
Keith H.

[scott/r]

I have noticed a marked reduction in es and sd readings after changing over to palma brass with my t/r rifle. Granted, the small flash hole has reduced overall speeds, compared to the standard win brass and large flash hole. Both being Lapua brass. Through reading other people's opinions and my own experiences, I think the combination of the small flash hole and small primer go a long way to reducing es and sd figures.
With the neck tension subject, good consistent annealing also goes a long way to help.
Scott.

[RDavies]

From what Ive seen, powder type and powder weight make a big difference.
Quite often I have seen better ES/SD with powders on the slightly faster burning side for your combination despite the case only being 85% full which goes against the old adage of always trying for 100% case fill, or close to it. I know with my 284s and SAUMs I got better ES/SD with 2209 Vs 2213sc and 2217. Same with my Dashers, 6BR, 6.5s and 300WSM, I usually got better ES/SD , though maybe not always highest velocity with powders on the faster side.

Next is powder charge, or the pressure. Most of the time the ES/SD will improve as you go up in powder charge and increase pressure until you get to over 55000psi but once you get too high, ES/SD will dip down again. I like to fire first shots with each case at reduced pressure on its first firing and have a fire form barrel for most calibres I have. With these first shots I always try to run one node, or about 130 fps slower than usual speed and ES/SD is never as good as when I stoke the load up to full pressure.

Primer selection also makes a difference and your firing pin/spring combination as well as your barrels personality might well prefer different primers to your friends combination. I know my Barnards loved PMC primers for my 284s and SAUMs but a local shooting friend of mine could never get these to work in his other actions. His rifle showed a definite preference to Federal primers, which mine never preferred in any calibre. When I start with a new cartridge or powder combination I will often do a primer test, trying 10 or so shots with 2 or 3 different primers over a chronograph and even with similar type primers, I would usually find one or two primers which went better in chronograph ES/SD than another popular primer.
On top of these, the case prep will be your next bet, but even having cases prepped to extreme levels as many of us are doing during these quiet times, you usually wont get very low ES/SD unless your powder type/charge/pressure and primer selection are right first.
As for whether low ES/SD makes a difference. At shorter ranges, say out to 600-700yds, ES/SD really doesn't make a massive amount of difference and with open calibers at least I have even been able to get good accuracy with not so great ES/SD out to around 800yds. At 900yds I start seeing improvement with better ES/SD and at 1000yds it often does make a difference.
I have heard of people shooting 100x more 1000yds than I do that they often got great accuracy at 1000yds with mediocre ES/SDs but I am not sure if their guns also kept in tube when shooting at shorter ranges as well as F class shooters often do.

[Gyro]

I have noticed a marked reduction in es and sd readings after changing over to palma brass with my t/r rifle. Granted, the small flash hole has reduced overall speeds, compared to the standard win brass and large flash hole. Both being Lapua brass. Through reading other people's opinions and my own experiences, I think the combination of the small flash hole and small primer go a long way to reducing es and sd figures.
With the neck tension subject, good consistent annealing also goes a long way to help.
Scott.

Litz did a heap of testing on annealing and it's effects on ES/SD and discovered the 'noise' was greater than any possible benefits. BUT since then the AMP guys have been a part of tests where the precision was marginally better with annealing. BTW my story here re the annealing tests is very shortened !!!!!!!

I believe in annealing after every firing. Perhaps it's about a better more consistent gas nk seal ? Better for reducing the generation of vibrations ? Better for more consistent ignition as the headspace is VERY likely more consistent ? Better just for my headspace ... ?

[Pommy Chris]

I have noticed a marked reduction in es and sd readings after changing over to palma brass with my t/r rifle. Granted, the small flash hole has reduced overall speeds, compared to the standard win brass and large flash hole. Both being Lapua brass. Through reading other people's opinions and my own experiences, I think the combination of the small flash hole and small primer go a long way to reducing es and sd figures.
With the neck tension subject, good consistent annealing also goes a long way to help.
Scott.

Litz did a heap of testing on annealing and it's effects on ES/SD and discovered the 'noise' was greater than any possible benefits. BUT since then the AMP guys have been a part of tests where the precision was marginally better with annealing. BTW my story here re the annealing tests is very shortened !!!!!!!

I believe in annealing after every firing. Perhaps it's about a better more consistent gas nk seal ? Better for reducing the generation of vibrations ? Better for more consistent ignition as the headspace is VERY likely more consistent ? Better just for my headspace ... ?

One of my best barrels has original brass, it is still tacking at almost 2,000 rounds with maybe 150 cases so case have been fired 13 or more times with 215 grain projectiles. Yes palma brass, but no annealing. As I said earlier in the thread I use moly so maybe this mitigates any neck tension issues, I dont know.
Why would annealing affect gas seal?
There is good evidence that the primer drives the projectile into the lands BEFORE the powder is ignited. Primers are very explosive and reaction is very very fast, far far faster than powder. The powder will just started to begin burning when primer has done its thing and projectile is lodged into rifle lands.
Gas seal does not really matter. Neck tension only to some degree, maybe how hard that projectile hits lands after primer.
Headspace?
That does not change unless you are badly full length resizing cases.
Chris

[Pommy Chris]

Like I have said before we all do what we feel is important, but annealing should only be done well, this is one process that could end very badly if done incorrectly.
Chris

[Gyro]

Headspace Christopher is just a nominal measurement the thinking reloader understands and manages.

[Pommy Chris]

Headspace Christopher is just a nominal measurement the thinking reloader understands and manages.

So explain why annealing affects headspace.
Your barrel should be chambered a few thou at most over go gauge, so new brass will only have a few thou at most headspace. When you fire form headspace is gone as the brass now fits the chamber. If you neck resize you are not affecting headspace, if you full length (I dont) then you need of course make sure you only bump back a couple of thou, this is the case not the neck. If you are annealing the case not just the neck this is dangerous. Annealing the neck does not affect headspace. Early flame annealing was a bit uneven as some cases got too much of the case annealed. From what I understand (not something I am very interested in) the conductive type annealing is really just neck as it should be.
Chris