Reducing ES and SD

[Morgan321]

I loaded once fired LC match brass with 175smk, imr4895(47.0gr), and federal magnum primers.

I chronoed five of my reloads and the results were in the mid 2500fps range with 119 spread and sd of 45! I shot four m72 rounds (1961 lot) and they were around 2520 with spread of 24 and sd of 10.

There is lots of airspace in the rounds, but the m72 are the same way and they shoot great. I used magnum primers because they were all I could get locally.

The brass was neck sized only and not cleaned except for a quick brush in the neck. My scale is a cheap digital jobbie, but seems to be very consistent(I have a couple pieces of metal I weigh to verify the scale reads the same, and it always does).

It's easy to say make everything perfectly consistent, but I have very limited time. What things would make the biggest difference - cleaning the brass better, a better scale, etc. I loaded the ammo with a lee loader but have a proper press now, I suspect the will help some. What else would make the most improvement?

 

[poison123]

Why the hell would you not clean your brass?

What Chrono did you use?

 

[Steve Williams]

Once fired LC brass was fired from several different chambers.

I would a least FL size to get some kind of consistent case volume working in your favor,
some of those chambers may have stretched the brass enough to cause volume, case to case,
to be spread quite a bit.

JMHO

 

[Big Z]

Clean, size, and trim all brass to the same length. Deburr flash holes then weight sort.

 

[Morgan321]

All the brass is m72 brass from the same lot and was once fired in my gun. Didn't clean it because I don't have a tumbler thingy.

Given that the factory m72 ammo has outstanding ES and SD, I don't think brass work other than cleaning or maybe sizing will help?

The brass all weighs 190gr +/- 4gr without cleaning. That seems pretty good to me?

I don't know what the chrono was, it was a range loaner. It was white and had 5 buttons though! The m72 and my ammo were fired through it about 5 minutes apart. I didn't use a different chrono or anything.

 

[poison123]

All the brass is m72 brass from the same lot and was once fired in my gun. Didn't clean it because I don't have a tumbler thingy.

Given that the factory m72 ammo has outstanding ES and SD, I don't think brass work other than cleaning or maybe sizing will help?

The brass all weighs 190gr +/- 4gr without cleaning. That seems pretty good to me?

I don't know what the chrono was, it was a range loaner. It was white and had 5 buttons though! The m72 and my ammo were fired through it about 5 minutes apart. I didn't use a different chrono or anything.

Honestly....you need to get a book on reloading. Did you even work up a load? Or did you just decide to dump a arbitrary number from I'm at least hoping is a manual not the internet into the cases?

 

[kd185]

Clean, size, and trim all brass to the same length. Deburr flash holes then weight sort.

X2
also index primer pockets and anneal to get better consistency
what kind of coal were you getting?
did you weight sort the bullets?
crimped?

 

[targaflorio]

I believe the M72 used 168 gr bullets. If you are running 175s faster than the 168 factory load, that's probably your issue.
I would try again at 45 or 46 grs
What's your rifle and barrel length and twist?

 

[Morgan321]

I loaded them to 3.28 inch because that's what the m72 is. No other reason and haven't tried adjusting it. No crimp. The 26 smk bullets I loaded were all 175.2 on my cheapie scale.... The Amax 168 I tried first varied from 168.2-168.6 on my scale.

24 inch 1:10 twist barrel. I posted couple days ago about the ocw I did with the smk, 47 and 46.6 both performed nearly the same as m72(right around 1moa). 47.4 and above gave rapidly expanding groups and big poi shifts. This was all done at 500yd, I will narrow the ocw range and do... 46.4 thru 47.0 in .2 steps at 100yd to settle on an exact load.

With a 120fps variation I can't help but think reducing it will help consistency... The m72 shot 24fps variation on the same chrono so the brass is good, I can only assume it's my lee loader hammering, powder measuring, or not spotless brass introducing so much velocity variation. Just curious if anybody can suggest which of those three will make the biggest improvement in velocity consistency?

Next round will be loaded on a press, so the lee loader is out of the loop. I'm going to try to get my brass clean too. I don't want to buy a fancy scale if I don't have to.

I tried to find somebody locally who has an annealing machine but no luck. I do not want to try it without a machine.

 

[Big Z]

1) anneal by slowly turning neck/shoulder in propane torch flame for 3-4 seconds, then drop in water.
2) 8 grains of case weight variation isn't very good
3) 4-5 shots of ammo thru a range-loaned chrono isn't much to go by
4) You can use hot water and dishwashing detergent after resizing to give your brass a light cleaning
6) Shit. Just go buy more factory ammo. I'm embarrassed thinking about that mallet and little yellow powder scoops operating on a "tight schedule."

 

[Morgan321]

I figure annealing by hand would introduce more variability than not annealing?

8gr span of weights for a 190gr case is bad? That's +/- 2%. Better than the polls on the news! I'll weigh them then and get better data. What is a good weight spread for cases? I've got plenty, I can use ones that are in a 2gr window for the next round.

I know, but I don't have a chronograph and it's all the data I have.

I haven't found any factory ammo that is as consistent or groups as well as the m72. Some hunting ammo is as bad as 6moa. There's a hornady match load that works good for me but its $2/round after tax or shipping!

 

[1slow01z71]

You need to step away from the reloading bench before you hurt yourself or someone else. You need to go back to square one and do a LOT of reading.

 

[mb3]

Cleaning and percise oal on your cases will make a big difference in your end product. How are you measuring your powder? I dont trust any method except a dipper and scale.

 

[Morgan321]

I put each case on the scale, 0 the scale, and pour the powder. Nothing fancy for sure. The oal is fine, I randomly measure to make sure it hasn't changed. Always within a few thousandths of an inch.

 

[black max]

I put each case on the scale, 0 the scale, and pour the powder. Nothing fancy for sure. The oal is fine, I randomly measure to make sure it hasn't changed. Always within a few thousandths of an inch.

You could probably save quite a bit of time if you changed this step. Get a powder trickler a funnel and a pan.

 

[Wildboarem]

Wow from what I read you should probably just sell your rifle and quit shooting altogether. your oal should be within .0000001, weight sorted bullets within .001 gr and weight sorted brass within -.05% polished to a mirror finish loaded on a press made in Germany, hand assembled by no less than 10 journeymen. Otherwise your a threat to humanity.
All kidding aside, if your oal is consistent (+/- .001) your charge is consistent (+/- .1gr) and your cases are a consistent weight (+/- 1%) which in your case is 4 gr or 3.8gr to be exact. Then I would look at primers, when I do load development the last stage is to load up exact loads with different primers to see if I can lower the sd/es. The other thing I would look at is consistent neck tension, but primers would be first. Look at maybe trading some to find the ones Your Rifle likes. Good luck.

 

[kansas]

I agree with the above. Primers changed my loads from double digit to under 10 SD. I was using Winchester LR and went to CCI BR2 however I have heard some very good things about Tula and Wolf primers. But, like you say, sometimes you have to use what you can find.

 

[6brshooter]

I love this site. I want extreme lr precision, but i don't have time for quality reloads.lol. I would try some different charge weights and some hornady or win brass. Deburr flash hole, i uniform pp but i don't really see any gain there, just one less variable . Those two things are a one time deal on that brass set. I have fiddled with primer testing and my conclusion is that they just change velocity. If u got a good load with br2 and decide to try 4 different primers with the original powder charge you will probably be let down. A fair test of primers to see which shoots the best will require a load workup with each different primer. My advice stick witg a quality primer and try going up and down .1 gr from the most accurate load on paper. Usually the most accurate load on paper is usually good over a chrony. If not then try going up and down .1 gr increments while shooting paper and over a chrony.
I have saw guys with a good load, lets say 44 gr varget, br2,&168 smk. They want to see which primer works better so they load the exact same load but with fed,rem, and cci. It is a waste of time, sure u might luck into a better primer but the deck is stacked against u, unless u do a new load workup with each primer tested.

 

[Morgan321]

If I was looking only to test how/if ES changes with a primer swap that seems logical? Obviously have to check out the load if the different primers do improve ES/sd, but any reasonable load would be suitable to only evaluate ES and SD change I would think?

 

[damoncali]

FYI it's not the dirty brass. I've shot aggs well under 0.4 moa with filthy brass. Cleaning brass is for ease of inspection and keeping your gear clean, not accuracy. There are no easy answers other than high quality components and testing to see what works. I'd start with the brass. 8 grains is a lot of variance.

 

[Wildboarem]

I love this site. I want extreme lr precision, but i don't have time for quality reloads.lol. I would try some different charge weights and some hornady or win brass. Deburr flash hole, i uniform pp but i don't really see any gain there, just one less variable . Those two things are a one time deal on that brass set. I have fiddled with primer testing and my conclusion is that they just change velocity. If u got a good load with br2 and decide to try 4 different primers with the original powder charge you will probably be let down. A fair test of primers to see which shoots the best will require a load workup with each different primer. My advice stick witg a quality primer and try going up and down .1 gr from the most accurate load on paper. Usually the most accurate load on paper is usually good over a chrony. If not then try going up and down .1 gr increments while shooting paper and over a chrony.
I have saw guys with a good load, lets say 44 gr varget, br2,&168 smk. They want to see which primer works better so they load the exact same load but with fed,rem, and cci. It is a waste of time, sure u might luck into a better primer but the deck is stacked against u, unless u do a new load workup with each primer tested.

If one subscribes to the OCW method, as a lot of people do, then first thing is finding optimum charge weight, then seating depth and then finally I find the optimum primer. I don't start from scratch and rework a completely new load when changing primers. Recently I developed a load for my wife's .243. I found a load that shoots right around 1/2 moa consistently. The es is about 30 and sd around 13 with WLR primers. I loaded everything the same except primers and kept same accuracy and smaller es
(-20) and sd (9) with Fed 210m. Br 2 were worse accuracy and worse es/ed. So I can get 1/2 moa accuracy with my RP brass that is unclean and not weight sorted with bullets that aren't weight sorted or sorted by ogive length and no, I don't want to spend lots of my time reloading. I want to shoot.
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