Painless load development (mine)

[streamerfish]

thanks guys. Any suggestions for a next step for the "painless load development" method. Shoot a 10 shot group with 4831 at 45gn & 4350 at 42gn? Or back down further. Then pick the best group as my load and let it rip at distance? FYI i was shooting a t 1500 ft and it was 90 degrees out, so I dont see my self hunting in hotter or low elevation than this.


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I apologize if I missed it somewhere, what's your overall length?

You can often times go a bit above max in a .243 due to the relatively low saami spec. But this is very barrel dependent.

Personally, I would be very hesitant to go more then 1 grain over book max.

 

[huntsd]

I apologize if I missed it somewhere, what's your overall length?

You can often times go a bit above max in a .243 due to the relatively low saami spec. But this is very barrel dependent.

Personally, I would be very hesitant to go more then 1 grain over book max.

I dont have that # with me right now. But I am using a M+ mag and am just inside of that. Guessing about 2.95-2.97 ".

 

[Alpha Echo]

I would also add to this......If your running the same powder, stretching the COL a bit, and adding proportionally more powder, your pressure curve is going to be roughly same, your velocity is going to be pretty similar. You might be squeezing a bit more out of it. But its going to be a pretty small difference, a white noise difference so to speak.

Your heading into painful reloading and out of painless reloading.......heading into the white noise space...

Super helpful, and logical, to look at percent change in COL to determine a rough ceiling for percent change in charge weight (assuming all else, including powder type stays the same) to maintain roughly the same pressure curve and velocity.

But yes, to your point, easy to fall into yet another rabbit hole.

 

[tim tarras]

The discussion about COAL couldn't come at a better time. I'm going to be building a 257 Roberts AI and loaded some dummy rounds with the bullet (copper) loaded to the neck/shoulder junction and wondering if they are actually too long. I am building on a Tikka action so they will fit in a LA magazine.

This is new territory for me as this is my first build so any help is appreciated. TIA.

 

[Q_Sertorius]

The discussion about COAL couldn't come at a better time. I'm going to be building a 257 Roberts AI and loaded some dummy rounds with the bullet (copper) loaded to the neck/shoulder junction and wondering if they are actually too long. I am building on a Tikka action so they will fit in a LA magazine.

This is new territory for me as this is my first build so any help is appreciated. TIA.

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To me, the first thing to establish is whether they will feed. If you are using those bullets, to me it looks like hunting loads. I don’t care how accurate a load is in a hunting rifle if it won’t cycle 100% reliably.

I’d probably load 10, cycle them through a bunch, then test fire one to check for pressure, then shoot the rest if that one looks okay.

 

[tim tarras]

To me, the first thing to establish is whether they will feed. If you are using those bullets, to me it looks like hunting loads. I don’t care how accurate a load is in a hunting rifle if it won’t cycle 100% reliably.

I’d probably load 10, cycle them through a bunch, then test fire one to check for pressure, then shoot the rest if that one looks okay.

Unfortunately, I don't have the barrel. I am going to be sending one of these to PBB for to determine the throat of the barrel.

 

[NWBLKTAIL]

thanks guys. Any suggestions for a next step for the "painless load development" method. Shoot a 10 shot group with 4831 at 45gn & 4350 at 42gn? Or back down further. Then pick the best group as my load and let it rip at distance? FYI i was shooting a t 1500 ft and it was 90 degrees out, so I dont see my self hunting in hotter or low elevation than this.


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Why not just back off to 40-41gr H4350 .050-.060 off, live in that 2850-2900fps range and never have to worry about it?

I load 108 eol, 108 eldms in a 22” Mcgowen barrel 40gr in Starline and Hornady sub 2900fpsavg for both and just shoot. I’ve got 300 round of 108eldm through this thing with 40gr and no drama ever. Even longer strings of fire.


Every chamber is different I’m not saying do exactly what I’m doing, I’m just saying, why even push it if you’re not even sure where you should be at? Drop the charge be realistic with your velocity and go shoot

 

[huntsd]

Why not just back off to 40-41gr H4350 .050-.060 off, live in that 2850-2900fps range and never have to worry about it?

I load 108 eol, 108 eldms in a 22” Mcgowen barrel 40gr in Starline and Hornady sub 2900fpsavg for both and just shoot. I’ve got 300 round of 108eldm through this thing with 40gr and no drama ever. Even longer strings of fire.


Every chamber is different I’m not saying do exactly what I’m doing, I’m just saying, why even push it if you’re not even sure where you should be at? Drop the charge be realistic with your velocity and go shoot

Is this out of a 243?

 

[Harvey_NW]

Unfortunately, I don't have the barrel. I am going to be sending one of these to PBB for to determine the throat of the barrel.

They should fit and feed fine in a Tikka. When I build a custom I load the dummy about .050" long (just lock a set of calipers and eyeball where it looks like the boat tail junction is +.050" of the neck/shoulder junction) and have them cut the throat for that to be "touch", for whatever bullet I plan to shoot. I recently learned how wildly different the bearing surface length can be on similar weight bullets, so I suggest measuring those dummies with an ogive comparator CBTO and seeing how close they are in that regard, and deciding from there. One loads .050" off the lands could be another loads +.070" jam.

 

[NWBLKTAIL]

Is this out of a 243?

Yes standard 243win chamber

 

[huntsd]

Yes standard 243win chamber

That’s the dilemma I’m in per the the book a 107 is over pressure by about 3gn at 41. Where the 108 eldm isn’t. Still seems weird to me to be able to push faster and put more powder behind a 108 vs a 107

 

[NWBLKTAIL]

That’s the dilemma I’m in per the the book a 107 is over pressure by about 3gn at 41. Where the 108 eldm isn’t. Still seems weird to me to be able to push faster and put more powder behind a 108 vs a 107

Are we talking smk or tmk? 107

Edit: have you measured their bearing surface? I bet that 107TMK is more akin to the 108 eldm profile

 

[huntsd]

Are we talking smk or tmk? 107

Im using a tmk but book is for smk

 

[NWBLKTAIL]

Im using a tmk but book is for smk

I think a better starting point would Hodgdon 108eldm data. I think a 107 tmk would be closer to that in profile than a 107smk.

Get a few firings on that lapua brass, then work back up. You will know right away where the wall is. IIRC you said it’s virgin brass?

For now just drop to that 2800fps range and shoot the rifle

 

[huntsd]

I think a better starting point would Hodgdon 108eldm data. I think a 107 tmk would be closer to that in profile than a 107smk.

Get a few firings on that lapua brass, then work back up. You will know right away where the wall is. IIRC you said it’s virgin brass?

For now just drop to that 2800fps range and shoot the rifle

yes virgin. thats what i am thinking too. though i called sierra and they said use the 107 data. just seems off compared to what data for the 108 shows. i could be very wrong tho

 

[NWBLKTAIL]

yes virgin. thats what i am thinking too. though i called sierra and they said use the 107 data. just seems off compared to what data for the 108 shows. i could be very wrong tho

I can’t speak for them.

Maybe the default answer for them since they have no data of their own with that specific bullet in 243win. Seems like the safe, smart thing for them to tell consumers to use the SMK data.

 

[huntnful]

yes virgin. thats what i am thinking too. though i called sierra and they said use the 107 data. just seems off compared to what data for the 108 shows. i could be very wrong tho

You’re not very wrong. They just gave a generic safe answer.

The 107 TMK builds less pressure than a 108 ELDM and can take more powder to get to pressure and should end up at a slightly higher MV as well.

Don’t get too caught up in the info they gave you. Just load up a 5 grain window of powder to test and go find out for yourself IMO

 

[tim tarras]

They should fit and feed fine in a Tikka. When I build a custom I load the dummy about .050" long (just lock a set of calipers and eyeball where it looks like the boat tail junction is +.050" of the neck/shoulder junction) and have them cut the throat for that to be "touch", for whatever bullet I plan to shoot. I recently learned how wildly different the bearing surface length can be on similar weight bullets, so I suggest measuring those dummies with an ogive comparator CBTO and seeing how close they are in that regard, and deciding from there. One loads .050"
off the lands could be another loads +.070" jam.

Here are the CBTO lengths.

This is the length difference.

HBC 0.69
LRX 0.639
HHT 0.527

 

[Harvey_NW]

Here are the CBTO lengths.

This is the length difference.

HBC 0.69
LRX 0.639
HHT 0.527

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So .179" total difference, that's a fair amount. I don't get up in arms if the bearing surface is seated into the case a bit, so if I were in that situation wanting to shoot those I would probably throat it somewhere in the middle where the longest may be seated into the case a little more, but the shortest isn't jumping a mile seated junction/junction.

 

[Eiden]

Threw together a load with this method.

Bullet seated to boat tail neck/shoulder junction. No clue how far it is off lands. 1/2gr below book max charge weight. Rounds shot in 5 shot strings letting the barrel cool between strings.




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