Reloading for 243 - what’s your thoughts?

[CountryONR]

Hi all,
First time reloading my 243, specifically Mauser M12 Black Impact 20” barrel. Fair to say I’ve enjoyed it and am quite happy with my results - what do you guys think?
Emailed Sierra for Min & Max loads for the Sierra GK HPBT using Viht N160 which was 39.4 - 44.4gn with a COAL of 65.786”.
Viht N160, Magtech Large Rifle Primers. Lee neck collet die and micrometer bullet seating dies.
Measured my max COAL with the hornady gauge which was 65.7mm so decided to go with a round COAL of 65.5mm to start with.
Loaded in 1 grain increments between the above loads and chronographed the rounds - see results below.
As I’m wanting a load for both fox and deer (manly roe with the odd red) I must meet a minimum of 3000fps with an 85grn projectile.
I decided to load between 43.4 & 44.4gns in 0.2gn increments - and tested those tonight.
And got the below results.
Think I’m going to go with the 44.2gn round - what’s your thoughts?
Fliers may have been me may have been the round - unsure, that said still under 1” at 100 yards and taken the flier out roughly 1/2” at 100.

 

[hendrix's rifle]

Start over with a starting charge of 43.6 and work up in .3-.4 increments until you see pressure. I reckon you can get considerably more speed out of them and I also think you will come across something that you will be happy with. Also I find diamond targets are far better for precision.

Out of the groups, none of them. But the testing hasn't been the best. The POI of all of them except the lowest two are miles apart. Also, whilst they're under 1 inch, don't discount fliers, they still count.

For what its worth, my 20 inch tikka is sending the 90g TGK out at just over 3200fps. I have used the 85g previously and they were a single ragged hole but performed awful on deer! They were just over 3200 if I remember correctly

 

[Smellydog]

Your last charge weight is probably where I would of started! Hate wasting components.

 

[Mr. Gain]

While I entirely understand your caution, I agree that your loads are almost certainly too conservative. My experience is that copper needs to be kicked harder than lead for best accuracy.

I wouldn't feel bad about taking a bit longer than hoped to get the load you are looking for. Just the time spent behind the rifle trying to shoot it as accurately as possible is worthwhile. Add the time spent making precise and consistent load samples, and you're absolutely on track for truly effective loading and shooting further down the road.

 

[CountryONR]

Your last charge weight is probably where I would have started! Hate wasting components.

Completely new to this to I was none the wiser but gotta start somewhere I guess

 

[Smellydog]

Completely new to this to I was none the wiser but gotta start somewhere I guess

You certainly are doing well.
If you want to you could measure the case head just up from the rim rebate and jot it down. Then after firing measure again.
An increase of under .004" per shot is fine.
If no growth in diameter you can certainly go further without fear.
It's a rough guide but better than guessing.
I can't do it with my 3030 but found it a good guide in my 243's, 308's , 6.5 and 270.

 

[25 Sharps]

Completely new to this to I was none the wiser but gotta start somewhere I guess

As you are completely new to this you have done exactly the right thing, followed the load data! It looks very much like Sierra have given you Vihtavori's data for the 87 gr V-max and Viht's data is known for being conservative. If there were zero pressure signs then you may choose to go a little higher 1 or so grains, in small increments, whilst being very vigilant for pressure signs.

Not sure which target you are referring to as you have 2 listed at 44.2, you can't discount a flier unless you shoot several more groups and confirm that it was a flier. The far right picture gives you the most power and the best group but is still only just above minimum. This will be a great round for roe and fox, personally I wouldn't use it reds, it is almost on the minimum and for a quick, humane kill your shot placement will need to be nigh on perfect. I have a 25-45 that makes around 1750 ft-lb with an 80 - 100 grain bullet, if I was out specifically for reds or a fallow buck I wouldn't use this rifle.

The other thing to consider is you may be using the wrong powder for your short barrel, Viht list 2978 fps for the 87 gr and a 23" barrel Sierra list 4 powders that give 3200+ with a 24" barrel and Nosler list 5 loads at 3184 + fps. Granted most of these are Reach affected powders, but there will be European equivalents and nosler list RL17 for 3184 fps, which is obtainable here as RS60. So a switch of powders may well get you more speed whilst remining within data.

 

[25 Sharps]

Start over with a starting charge of 43.6 and work up in .3-.4 increments until you see pressure. I reckon you can get considerably more speed out of them and I also think you will come across something that you will be happy with. Also I find diamond targets are far better for precision.

Out of the groups, none of them. But the testing hasn't been the best. The POI of all of them except the lowest two are miles apart. Also, whilst they're under 1 inch, don't discount fliers, they still count.

For what its worth, my 20 inch tikka is sending the 90g TGK out at just over 3200fps. I have used the 85g previously and they were a single ragged hole but performed awful on deer! They were just over 3200 if I remember correctly

What powder are you using?

Agree on the targets, I like these as you can get 5 load weights on one sheet and the grid in the background allows you to easily see how the individual groups would overlay relative to the point of aim. The diamond shape also helps with consistent alignment if using a lower powered scope.

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[WW.]

While I entirely understand your caution, I agree that your loads are almost certainly too conservative. My experience is that copper needs to be kicked harder than lead for best accuracy.

I wouldn't feel bad about taking a bit longer than hoped to get the load you are looking for. Just the time spent behind the rifle trying to shoot it as accurately as possible is worthwhile. Add the time spent making precise and consistent load samples, and you're absolutely on track for truly effective loading and shooting further down the road.

I'm a complete beginner from the reloading and ballistics angle, but from what you said it strikes me that since spin is the thing which makes the bullet stabilise in flight, and copper often needs a greater twist rate to the barrel, copper typically needs to spin faster than lead does to stabilise. Is this right?

I guessing there's also an optimum spin rate, beyond which there are no further gains, or even a loss, in accuracy?

If the twist rate and barrel length are fixed, presumably the speed at which the bullet traverses the barrel is what can be adjusted to adjust the spin rate, so if you know the ideal spin rate for the bullet and the twist rate of the barrel, you can work out the ideal powder charge to use? I'm guessing the real anorak would also factor in friction through the barrel, efficiency of powder burn and losses through sound, heat and recoil?

Sorry if it's a stupid question, but is the above broadly correct or complete rubbish?

 

[Smellydog]

The the spin rate remains constant, it's rpm we alter.
Increase velocity and rpm rises.
Often overlooked is the time factor.

444Marlin started with a slow twist. The design didn't factor some may want to load 300 plus grain bullets which need more rpm.
Pushing them fast enough to get the rpm is a struggle in that cartridge.

 

[WW.]

The the spin rate remains constant, it's rpm we alter.
Increase velocity and rpm rises.
Often overlooked is the time factor.

444Marlin started with a slow twist. The design didn't factor some may want to load 300 plus grain bullets which need more rpm.
Pushing them fast enough to get the rpm is a struggle in that cartridge.

Sorry, should have said RPM. Again, lack of knowledge on my part! Should have thought of time too although I'm guessing that only goes so far?

 

[25 Sharps]

I'm a complete beginner from the reloading and ballistics angle, but from what you said it strikes me that since spin is the thing which makes the bullet stabilise in flight, and copper often needs a greater twist rate to the barrel, copper typically needs to spin faster than lead does to stabilise. Is this right?

I guessing there's also an optimum spin rate, beyond which there are no further gains, or even a loss, in accuracy?

If the twist rate and barrel length are fixed, presumably the speed at which the bullet traverses the barrel is what can be adjusted to adjust the spin rate, so if you know the ideal spin rate for the bullet and the twist rate of the barrel, you can work out the ideal powder charge to use? I'm guessing the real anorak would also factor in friction through the barrel, efficiency of powder burn and losses through sound, heat and recoil?

Sorry if it's a stupid question, but is the above broadly correct or complete rubbish?

It’s not that copper needs more spin per se, it’s that longer bullets need to spin faster to remain stable. Copper is lighter than lead, by a fair bit, so an 80 gr bullet made from copper will be longer than an 80 gr bullet made from lead, by a fair bit.

Friction does come into it and twist rates also affect velocity.

You are right in that if you push a bullet faster it will spin more with any given twist rate but you have the limiting factors of barrel length, case capacity and pressure ceiling of the cartridge. Once you hit that pressure ceiling it is unsafe to push the bullet faster, though you almost certainly could, at the risk of a face full of gas or worse a gun blowing up.

You need to select components to match your barrel, cartridge and what you want to achieve, and be honest that you may not get there. It’s the reason my 25-45 has a 25” barrel.

 

[WW.]

This is very interesting, thank you for the replies.

So starting from any given constants, any theoretical ideal cartridge setup for accuracy can be calculated?

Do individual rifles sometimes ever 'not play ball'?

 

[25 Sharps]

This is very interesting, thank you for the replies.

So starting from any given constants, any theoretical ideal cartridge setup for accuracy can be calculated?

Do individual rifles sometimes ever 'not play ball'?

Yes, there are online stability calculator tools that you can use as a guide. Barrels and chambers vary, so you may have a fast barrel that outstrips the data, or a tight chamber and a slow barrel that shows pressure way below max.

The only way to find out for sure is to run the test loads, which is expensive these days!

 

[Smellydog]

I always think the friction factor is over stated.
Once the bullet is swaged the friction is minimal.

 

[25 Sharps]

I always think the friction factor is over stated.
Once the bullet is swaged the friction is minimal.

It certainly isn’t enough to worry about for hunting loads!

 

[6.5-06 TIKKA]

Just couldn't go by 87gr Vmax, devastating on deer never mind fox.
On paper 4 in single hole.
20 thou off lands.
N160, Lapua brass, 210M Fed priner...
80gr Sierra ProHunter were brilliant too.
Hope thus helps.