[Ericbc7]

Welcome, and good question.
With its 1:11 twist the t3 300wsm should shoot the 150 gr ttsx very well.  You might even go a bit heavier. 
barns recommends 50 thousandths.  Use that number to get your powder wt decided and play with seating depth from there.

Good luck and these are grat hunting bullets.

[Ericbc7]

I don't have experience with sleds, but I am sceptical that they are the best way to test loads.

If you find the recoil distracting or objectionable you might want to change gun/caliber.  Note that recoil is just one part of the issue.  As a bullet accelorates through the bore, the rifling imparts spin wich in turn creates torque on the rifle.  Heavy bullet & fast spin = more twist force.
Anyway get a good bipod and rear bag.

[Ericbc7]

Can you give us more detail?  What is your end goal?  I mean what rifle do you want to end up with (forgive grammar ending with preposition.)

[Ericbc7]

Thanks for the reply, I'll keep a close eye on it!  Based on your picture, your brake is well centered at least.

[Ericbc7]

Had a buddy do a fly in moose hunt 2 yrs ago, he used a 338 mag with Barnes ttsx and I think Browning A-Bolt (not sure).  I saw the pictures of the beast and “wow”.  He was in Alaska but you should see similar.  He and his non hunting wife both claimed that early bull moose is the best meat they ever had.  He bought a deep freeze at SAMs club or similar in AL, filled it with moose and shipped it home to ND on a truck going that way.

I say “early” bull since when they get deep in rut the meat quality suffers.  His hunt is a good story and I don't think I can do it justice but I'll try:

He hooked up with a gold miner in Alaska somehow and got an invite to hunt.  Long story short he made it up there and helped out with some mechanics and bunked with the miners.  They knew a big moose was around but the guys were totally focused on the job.  These guys basically dragged a full tanker semi of fuel with dozers to mining site (miles) that winter over 30 days or so at about 1 mile per day.  Budy was on a ridge and saw moose moving to airstrip, he dropped his pack and he set out running.  He got to berm near strip after about 1/2 mile or so and was near puking his guts when bull stepped onto runway.  WHAM first shot seemed good given hyperventilating, and WHAM 2nd shot more of same.  Bull leaned over and layed down.  Mining guys drove loader over and when picked up, that sucker was easily twice as tall as Hunter.  Massive bull and big deep freeze full of meat shipped home!  Both shots were kills one through part of heart.

Btw AL is terror on fly in and shoot hunters.  You must wait a day or so after arrival before shooting.  They are serious, and have power to arrest for violation and waste.  If  a hunter violates he will go to jail!

[Ericbc7]

Hey Dog, not sure I'm clear on what you mean.

Do you mean that when you start getting variable oal's you know your over compressing?

I plan to use the same neck sizing setting for each round (using the “consistent crimp” torque handle) and Lee collet die.  Seating bullets with forster micrometer seating die.

All cases will be 2nd fireing and neck sized with the Lee die.  In other words I fired the new cases with 23.9 gr benchmark and 52 gr bthp moly and rem 7.5 primers.  I will anneal for next loading. I mean 3rd loading which will not be part of testing

K reread your last post and think you meant “non” uniform coal.  I hear that and depending on neck tension that should be a good measure.  Since neck tension cannot get much above 2 thou due to nature of brass, variable oal over bullet vagaries should be good measure of over compressed loads.

[Ericbc7]

Hey Dog, great advice and thanks for saving me some time.  I too have used my sonicare toothbrush to settle powder charges, the drop tube seems to work ok inlieu.

How do you determine how much “crunch” is too much on compressed loads?

As far as coal, I have mags that let me load out to 2.6 or so, but I will seat bullets to 10 thou off the lands for testing.

[Ericbc7]

For 1:12t look at the Hornady 52 gr bthp. I have a 1:8t barrel and have not run it through the mill yet but it seems to sit in the sweet spot for your barrel.  Get it up to 3k and do load development.  It wouldn't hurt to try the 40+ gr heads with your slow twist.

[Ericbc7]

The 35 Whelen is a great cartridge!  I don't have any first hand experience with it but you are all set for Moose and Elk!

As far as groups are concerned, you can minimize the variables.  Get sand bags set up so each shot doesn't make you change anything.  In other words, if you are not touching the gun, the scope crosshairs sit on the bullseye.  Snuggle up without changing anything and touch off the shot.  Your groups will be representative if not tighter.

[Ericbc7]

Nice rifle friend!

If you hand load I think you will get that group down by half easy.  Also nice scope!

[Ericbc7]

Can you give details?

[Ericbc7]

Yea 2500 round in .243 is way over likely life for a factory barrel.  Even competition barrels in this caliber often burn out before 1800 rnds (some at less than 1000).  If you want to extend your replacement barrel life you might want to look into salt bath nitriding your replacement barrel.  If you bore scope the barrel and see “alligatoring” you might be able to cut the barrel and re chamber for a few hundred or 1000 rounds, but better to get a new barrel.
My advice is based on reading forums not personal exp.

[Ericbc7]

A right handed good friend of mine lost vision in his right eye 20 years ago.  He had his Ruger Red Lable shotgun modified with a very high (2″) rail so he could use his left eye.  He tried learning to shoot lefty but no success, he is a dead shot with his current set up.  I recommend not fighting your instincts and work around your instincs. Since you have a righty action and assuming you want to adapt to it with lefty inclinations… Then practice, practice practice.

If you want to embrace “leftism” (not politics btw) by all means save for a lefty version of your rifle and sell your righty!  You will, I think, find your scores improve if you stop fighting your natural tendancies.  It is similar to natural position behind the rifle.  I don't claim this is true, it's just my opinion.

Regardless, have fun!

[Ericbc7]

Thanks for the info Dog Down.  Makes me wonder what great stuff I have missed on the Internet due to limited imagination on searches!

[Ericbc7]

Has anyone used the new IMR4166 in this round? -it seems to be near 4064 according to a guy with the handle catshooter on the forums.