Working up a load, how much ammo?

[Blackstuff]

Hello all,

When examining the performance of a bullet/powder combination, how many rounds of each combination do you generally make up for test firing? My initial thoughts are 9 or 12; for 3 or 4 groups of 3 rounds per group? Thoughts?

Also, when stepping up from minimum to maximum (or however close to maximum you're planning on getting), what sort of increments, in grains, do you move through? The range given for the load data for the bullet/caliber combinations I'm planning on using is around 3-4 grains. 1 grain increments?

Any info appreciated

[ovenpaa]

I work on .5 or .3 grain increments dependant on the cartridge capacity and reduce to .1 grain when fine tuning. Once I have got as close as I can on powder volume I work on the OAL and bullet jump or jam.

5 shots for groups however this is not always ideal on barrel burners so I prefer to ladder load and record MV's and down range position (Ideally 2-300m) Looking for bullets in closer proximity versus the recorded data. The Vikings 6,5-284 load development was completed in 10 shots as was my 7mmC SAUM Wildcat. My first 7,62x51 AI took considerably more due to the sudden disappearance of both the powder and projectile I had chosen.

[Blackstuff]

I usually go to the range 'ammunition heavy' but I think I may be setting a personal record when I start this as I've got 3 different bullets to trial as well and so far only 2 dates for the rest of the year to do it This is also at Ponteland where the wind is very often strong and directly across the range aaarggh

I think I might need to be book a day down your way at the tunnel at NCB soon

[ovenpaa]

The NCB tunnel is used on an informal basis so get in early or shoot over an evening. We were there on Monday afternoon and it was quite cool inside despite full sun outside.

Do remember to take some white paper (Cheap wallpaper is good) as a backing sheet and copious amounts of masking tape to stop the backing flopping around. My final tip is to be aware the camera is not centred on the tube so have a look at what is already in place via the screen at the firing point and make a mental note of the centre line. I walked back and forth 5 times Monday so it is a good exercise for short brisk walks/runs :)

I always end up with a headache if I am shooting something spiteful despite wearing MSA Sordin defenders and I keep meaning to take additional ear plugs.

[Blackstuff]

I zeroed my MARS there on Sunday! (well the ACOG anyway - I zeroed the red dot on the 25m range ) I know the tunnel is rated to .50BMG but I couldn't even imagine shooting one in there, my .223 was bad enough! We were using a car to go up and down as we're lazy buggers, plus now they've smoothed out the hump next to the firing point building its a lot easier to do so!

[WelshShooter]

Typically I start 10% below maximum load and work up in 1% increments. I load five rounds at each interval giving me a total of 50 rounds to shoot. My main criteria is centre-to-centre grouping, deviation from POA (with respect to other groups) and velocity (average and extreme spread). Once this has been established I then look at the overall length to fine tune the accuracy. I normally try three additional seating depths with five rounds per group, so that's another 15 rounds. Assuming I have a load developed at this point, that's 65 rounds in total.

One other thing I consider is the effect on accuracy and velocity when grossly changing the powder charge weight. For example, if I maintain good grouping and no significant difference in muzzle velocity when I throw 45.0gr to 45.6gr then I'll consider that to be good as I don't have to be pedantic about throwing the same charge within +/- 0.1gr.

It's always worth repeating load development from time to time if you're not a good shooter (I'm not implying anything!). There have been times when I've been shooting my rounds for load development only to flinch on a shot, not have the rifle shouldered properly, not adjusting the scope correctly etc. It's only a good load if you can repeat it on a number of occasions.

If I change a component (for example, a different brand of bullet but the same mass) then I'll only deviate slightly from an already established load (obviously working from the lower end back up). I'll repeat the entire exercise when starting with a new powder or bullet mass.

This procedure has worked pretty well for me so far.

[Blackstuff]

Is there a reason you start at 10% below the maximum, as opposed to say, 10% above the minimum/somewhere in between? I'm a tight bar steward so i'll be looking to get the best result with the minimum amount of powder

Fortunately I don't think i'll have the additional variable of seating depth to contend with as the bullets I need to use seem to be at the maximum OAL so I don't have a choice (69gr SMK, 75gr Amax and 77gr SMK - .223Rem), and they need to be magazine compliant.

Out of interest, do you start at the recommended seating depth/OAL and then work up or down? Sorry if that's a total noob question.

[WelshShooter]

I usually start 10% below maximum if no minimum load is stated (for example, there are customer loads on Reload Swiss website), if a minimum load is stated then I use that as a starting point and increase at 1% of the maximum load, until I reach the published maximum load (hopefully that makes sense?).

With regards to seating depth, it depends. If I'm using a magazine I will start at magazine length and reduce overall length if it gets me better results. For single feeding, I will increase the overall length to minimize bullet jump if it gets me better results. All of my .223, .303 and 8mm loads are at the recommended overall length or slightly lower to ensure reliable feeding from the magazine. For my .308 my 155gr Lapua Scenars are just outsite magazine length so I single feed these - all my other .308 loadings are currently magazine length. My 6.5x47 can be seated as far out as possible because I use .308 magazines which allows me to do so. As such, they are seated around 0.004" from the lands.

Also, no such thing as a noob question :)

[Blackstuff]

Thanks for taking the time gents

[Maggot]

It also depends what you are reloading for. F class can take ages and you may well repeat the process as the barrel wears. For military mag loaders you often end up loading to mag length and working on the load alone which saves a lot of faffing.