243 falling on it's face

therifleman556

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Hi all...
I recently started working up loads for the 107 matchkings and 75 grain V-MAXES using IMR 4831. I started within loading manual recommendations and found decent accuracy. I had not yet had a chance to chronograph anything though. Afterwards I had a chance to run them over the screens and was shocked to say the least. 41 grains under the 107s netted 2620 fps and 46 with the 75s barely broke 3000. I was expecting at least 2900 and 3400 respectively. This is out of a 24" 1-8" twist McGowan barrel that's currently got a little over 60 rounds through it.

Anybody run into a barrel that slow compared to published data?

Next step for me is to see where pressure is with this powder and just what it'll do.
 

Andrew Massi

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Yes, some barrels are slow
But
I'd load up 40 rounds and keep shooting. Many barrels will speed up(and add pressure) as they season. As a rule of thumb, I dont push pressure and do any serious load development until over about 100 rds or velocity stabilizes
 

BallisticsGuy

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Okie dokie... IMR 4831 is too slow for 75's. You need a powder with a burn rate closer to IMR 4895. That would pump you just over 3400fps at 41gn charge weight (max). Come down to 40 grains and you should see 3300. You can't run the same powder for light bullets and heavy bullets and expect both to perform. They need different powders.

Now, with the 107's, yeah that's a little slow but not that far off what you should expect. It's almost 200fps slow though so I'm betting that you're not getting enough chamber pressure before the bullet leaves the neck and it's entering the throat soft. Part of that would possibly be helped by snugging up the neck tension or possibly by seating to touch the lands. I don't like those solutions though as they don't have legs for the long run.

You should definitely try a magnum primer to get better light-off but honestly, IMR-4831 is not a great powder choice if velocity is what you want. I can tell you that around 42-43gn of Reloader 23 will push you just over 3k fps easily (experience with 107/108's there). At 40 grains it'll be down around 2800 and soft on pressures.

Now to the marrow: Retumbo/H1000/Win 780/Reloader 22 and other proper magnum powders are where you need to go with the 107's. I found that I got better results with VERY slow powders and heavy bullets in .243win and much tighter SD's by going with a fairly warm primer. CCI MLRP's, Winchester LRP and F215's all served very well. Winchester LRPs (marked for "regular or magnum loads") worked the best in my particular loads.

HTH!

FWIW, right now I'm running 45.7gn of RL23 in a .243AI under 115DTAC's and getting 3200fps with totally sane pressures from a 26" Columbia River Arms barrel. I started with 108 ELD-M's and 55gn varmint pills during fire forming and got a lot of load data out of that development cycle.
 

jjmp

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your barrels still not broke in ,it just didn't like what you feed it. Ballistiguy made some good points , but i'' still say imr 4831 is a great powder just not for both of your bullets,my 243 bbl is the same make as yours but runs a 1/10 twist and im Very happy with its performance . I crossed referenced one old Sierra manual for you and it said 2800 for your 107 bullet and it agreed with your 75 v max load should have been 3400 . but don't dispar,your bbl is GREEN .just needs mor shooting NP!!!!!!!!!!! another point ill make is I don't use magnum primers with non / magnum cases ever even with ball powder ,I get my speeds with wlrp or f210s . yes even in the cold ...NP ... Nothing Wrong With any 243 !!!!!! NUFF said Cheers!!!!
 

sable tireur

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I have to run with Steve on this one, 3700 with 75 gr. VMAX and Re16.

On the 105/107 weights, I will disagree with the H1000 suggestion as my lot is WAY too slow to achieve what can be done with other powders better suited to the use. Re-26, IMR-7828SSC, and VVN-560 will all get you to 3200 at least. Re-26 does this apparently with slightly lower pressure according to my tests.

From Hodgdon's Data Center:

upload_2018-9-30_14-43-21.png


upload_2018-9-30_14-41-43.png






These 107 grain loads, I simply don't agree with because of the limitations of the powders. Much better performance can be had easily.
 
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therifleman556

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I've got a little RL 26 I could try for the 107s and some 22. For lightweights I've got 15, 17, or 19. My reasoning for 4831 is it's availability. RL 26 and 17 are not readily available locally. My choices for easy to get powder are Reloder 15, 19, and 22. Otherwise my only other choices are H4895, H414, or IMR 4831 and 4350. I haven't had good luck with anything that I've fed RL22.
 

sable tireur

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Re-22 is too inconsistent.

Re-19 will work with the 107 but you will not get to the 3200 mark. Mine topped out just a tad over 3000.

Re-17 will work for the 75 grain, you will not have a full case for consistency and it is not quite as temp stable as Re-16. But I shoots tons of Re-17 and haven't run into a problem yet.
 

Tyler Kee

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RL-16 worked some magic in my 243 which has an 18" barrel. I'm sure that adding another 6" of barrel would certainly help your velocity woes. This is my load for the Barnes TSX.

*****Disclaimer: My gun. My loads. Safe pressures. Don't load this directly and stick it in your gun*****

Case: Hornady FL Resized
Primer: CCI BR-2
Bullet: Barnes 85 gr. TSX
Powder: RL 16 (42.3 gr)
Loaded .050" off the lands
2908 fps

I found a sweet little accuracy node for 95 gr BTs @ 2850 fps with that powder as well. H4350 and the 90s seemed to be a better combo. Either of those powders do really well with the heavy(ish) bullets. Here's the 4350 & 90 gr BTs

Case: Lapua
Primer: CCI BR2
Projectile: Nosler 90 gr ballistic tip
Powder:H4350 (44.3 gr)
Loaded .030" off the lands
2970 fps
 

therifleman556

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I'm over 100 rounds into the rifle now. The last trip out I tried to find max pressure with 4831. I hit 44.0 grains (3.5 over book) and still only hit 2870. I think there's still room to run (no signs of hard bolt lift or primer flattening, etc...) but I'll move onto RL 26 instead.

I revisited Ramshot Hunter with the 75s and managed 3500 fps with magnum primers and .2 grains left in the book. Accuracy was very good but ES was 40+. I may try to tweak that a couple tenths and try a primer swap. I'm not too worried about hair splitting accuracy with that bullet. I'll finish off the pound of Hunter and probably move on to other choices.

On a possibly related note: I started neck sizing with a Lee collet die. I used those cases to begin work with RL 26 and the 107s. I noticed the neck tension was much lighter, once the bullet was started it only took a finger's worth of pressure on the handle to get them seated. This isn't to say that the other loads seated hard, but is excess neck tension causing more pressure to be wasted getting the bullet out of the case to begin with?
 

therifleman556

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Worked up to 48.5 grains of RL 26 with the 107s. Two rounds of each half grain increment went
46.0 - 2946
2970

46.5 - 3015
2983

47.0 - 3051
3052

47.5 - 3065
3057

48.0 - 3147
3156

I didn't notice anything to indicate that these are too warm. I might work a bit higher in .2 increments to see if I run into pressure or run out of case.
 

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