.243 Win Reloading

[J.Rod]

I am new to reloading, I have a Remington 700 SPS Varmit .243 9 1/8 Twist. I know the basics of prepping the brass up to the point of powder and bullet seating. I am reloading a Hornady 80 grain GMX bullet and the powder that I will be using is Superformance. The manual show's to start from 38.9 minimum to 45.4 max. Where does everyone start at the minimum and work their way up and what do you look for to find that final number of grains? Also bullet seating, I have a hornady OAL gauge that I used to measure this bullet touching the lans and I got 2.252. I have read that you should back the bullet back 5k,10k,15k, and 20k and find which one groups best is that correct?

 

[JEFFPPC]

Well yes and no. As far as seating depth I would start .020 in the lands and back up .003 at a time until I found a sweet spot. To do this I would start at 43.0 grains . Once I found a seating depth that was best I would from that depth start adding powder .3 at a time. With the powder found I would go back to seating depth but now changing .001 at a time about 3 bumps each direction to verify seating. The original seating depth test I do with 2 shot groups. If the 2 shots touch I shoot a third shot. If they don't I go to the next depth. Before you do any of this I would bed the rifle, free float the barrel,and tighten the action screws snug. It's very popular to star at touch and move the bullet back into the case but I have had many barrels shoot their best with the bullet engaged in the rifleing, thats why I adviise start in and then back the bullet into the case as you go. Verify touch by seating a bullet in an empty sized case, chamber it, take is out and look at it. You will see tiny marks from the lands, if not you are not at the lands. No special tools required.Now if you measure from the base of the bullet to the front olive of the bullet you will always know where you are in relationship to the lands. I do a lot of 2 shot groups unload developement, if two shots are not what your looking for a third will not make it smaller. Limit wasted shots, a .243 is usually going downhill by 1000 rounds as far as good accuracy. Good luck, have fun.

 

[Hohn]

I would not recommend considering an overall length jammed into the rifling for a hunting rifle with a monolithic bullet. That's a good way to get an action full of powder. You might chamber and rechamber the same round many times. There's almost always another OAL that will shoot more than adequately for hunting without the risks of running a jammed OAL.

I personally don't start at the bare minimum because I've fired enough rounds in my guns to know where I hit pressure. I know that if I hit pressure well past the book max of one powder, I'm very unlikely to hit dangerous pressures in the middle with another powder. I don't know of I'd start as high as 43.0, but I certainly wouldn't drop all the way down to 38.9. Things just get too inconsistent at low case fills.

Here's what I do:
1) Do a coarse pressure ladder in ~1% increments to identify where I hit pressure with a given powder/primer/brass/bullet in that gun. If charge weights are in the 40gr range, I will load increments of 0.4gr. Load one round each. So you start here maybe at 42.0, then load one round each from 42.0 to 45.6. This is ten rounds. You might consider misting these rounds with water as this will show very clearly pressure when it occurs. If you pass pressure with wet rounds, you're safe as the dry round will have less pressure.

2)Coarse OAL testing. Once you find the OAL to the lands, you need to see if it fits in your magazine. The longest round you can load is the one that is out of the lands AND fits in your repeating magazine, whether that's a hinged floorplate, detachable box, or blind magazine. I assume a hunting gun is a repeater. Start at this maximum length and load two rounds of each length in 0.010" increments until you've covered the range from your longest acceptable bullet to the shortest OAL allowed (limited by bearing surface of the bullet usually-- should be indicated in your load manual). This might be only 10 rounds, but it might be as many as 20 or 24 depending on the difference between the max and min lengths.

Make a target that is one horizontal line with a vertical hash for each OAL you wish to test. Let's say you have 6 OALs you are testing because you have .060" range between longest and shortest loads you can use. You'd load two of each, 12rds total. Your target would have six vertical lines about 1.5" apart and one "horizon" line. Label each vertical line with the respective OAL. Shoot one shot of each OAL at the point of its vertical line meeting the horizon, going left to right. Then start at right to left and shoot each OAL into it's respective POA (intersection of vertical and horizontal). You're looking for the OAL that has both shots with little vertical AND has the neighboring OALs very low in vertical scatter.

3) By now you will have identified a charge weight you cannot exceed as well as a range of OALs that has reasonably stable vertical. Drop down a grain or so from your max pressure charge and use that value for "fine OAL testing."

4) Fine OAL testing: Your coarse OAL testing will have identified at range of .020 or so that had the most stable vertical dispersion. Now we will split up that same range into increments of .004" or so. Load your "warm but safe" charge and and two shots each of your selected OAL range. Repeat the target and firing protocol of the coarse OAL testing. You will have identified some OAL that has consistent vertical point of impact not only for its two shots, but similar to its neighbors on your target. THIS IS YOUR OAL.

5) Now that we have the ideal, we go back and refine the charge weights. Load up three shots in small increments (maybe 0.2gr) on either side (lower and higher) if your "Safe but warm" load you used for OAL testing. Maybe you go up 0.6gr and down 0.6gr. You will top out around 0.4gr below your identified max. This is 18 more shots- 9 heavier than your OAL charge and 9 lighter.


This method seems to give good results while staying below 50rds in most cases unless you have a really long OAL magazine and have a larger range of OALs to test. If you need to minimize round count, do your coarse OAL testing at 0.020" increments.

 

[std7mag]

Hornady, Nosler & Barnes all recommend a 0.050" jump to the lands for monolithic bullets.
Monos like a jump.
For powder charge, start low. I work up in 0.3gr increments, then shoot a ladder test.

 

[dgeesaman]

With great respect to Jeff,

I think on this rifle you should fully explore setting your bullet depth to stay out of the lands. For practical reasons, avoid jam unless you find it necessary. Seating the bullet to jam into the lands means you can’t unload a round without firing it. Also it may not fit within the magazine. Do follow his suggestion to estimate the touch length for each bullet. I’ve used that method and it does work.

I would explore the full range in the loading manual. I started loading for a factory .243 recently and even 0.5 grain increments are feasible. Unless you’re focused on maximizing velocity, test the full range. Then once you have a preferred charge weight, test different seating depths.

I would stick to the book load recipes as much as possible unless you have a chronograph and a reasonably full complement of reloading accessories.

David