SmallCaliberCentral

I plan on getting one of my bolt action rifles re-chambered in 6x45mm but my choice of twist rates are 1:14 or 1:10. I plan to shoot between 60 to 85 grain bullets. The 1:14 will not handle the 85’s, but should be fine with the 60’s to 70’s. The 1:10 will do all of the bullets plus more, but at the sacrifice of velocity. Which would you recommend?

Accuracy trumps velocity. I would go with the 1/10 .

Bill K wrote: ↑Fri Nov 20, 2020 10:44 pmAccuracy trumps velocity. I would go with the 1/10 .

My mantra also. Agree 100%.

(What good is zippy velocity if you don't hit that dinky little target way out there? )

Thanks so much guys… That’s the way I was heavily leaning, but then you start to second-guess yourself.

I would like to hear how your project goes.
I put together a 6TCU rifle a couple of years ago. I wanted a 1-10” myself, but all they had in the profile I wanted was a 1-8”. 55-75 grain was all I planned on using. All I have shot so far are a bunch of odds and ends of various odd lots I had that needed used up, 60-80 grain fire forming loads.
I have some 55-65’s patiently waiting.
Am hoping the extra rpm adds to the splat factor on prairie dogs.

I did a 10 twist which shoots the 58g up to 75g very well. I have not done a lot load development with the "heavy" ones yet, but loves the 58g vmax.

Loosing speed from fast twist, any ideas of what the loss is?

jsh wrote: ↑Thu Nov 26, 2020 7:20 am I would like to hear how your project goes.
I put together a 6TCU rifle a couple of years ago. I wanted a 1-10” myself, but all they had in the profile I wanted was a 1-8”. 55-75 grain was all I planned on using. All I have shot so far are a bunch of odds and ends of various odd lots I had that needed used up, 60-80 grain fire forming loads.
I have some 55-65’s patiently waiting.
Am hoping the extra rpm adds to the splat factor on prairie dogs.

Looks like I’ll find out in about 6 to 8 weeks… I’m having one of my Cooper model 21’s MTV re-barreled in 6x45. Already have cleaned up a bunch of 223 brass and sorted it. Plan on starting off with Sierra 70 matchkings for target work and also have available Berger 65 and 68 flat base target/varmint. I have Sierra 85 grain Gamekings standing by for heavy testing. The dies will arrive today and have 2 powders for testing, RL 10x from the Berger manual and H 335 from the Sierra book. Would like to find some H322, but we all know what “fun” it is trying find powders and primers right now.

Looks like it will take longer to get the Cooper done. Will have to wait for them to get another barrel in. Should be ok and back in time to work up some loads. Great customer service at Cooper, keeping me in the loop and all.

6TCU, 1-8” twist 70 grain TNT running 2900 and change.

Mine is 14" Bbl from SSK and 1:10" twist
Had to build some remedial woodwork on this one
Powder of choice IMR 8208 with 62 gr. bullets = shoots lights out

gemhur, just have to ask.....what is the purpose of the old 'military style' forearm handguard on a varmint rig? Never seen that done before on a rig set up for accuracy. Most rigs are set up so that the forearm in no way actually touches the barrel when it's free-floating. I would also think the full enclosure would trap barrel heat; the enemy of a nice barrel.

Enlighten us please......inquiring minds want to know.

Update…. I got the rifle back from Cooper and started my load development. Using H335 powder and Bart’s 68 gr. Ultimate bullets to start. I have some 80 gr. Dominators on order, but I figure they will be a long time coming due to component shortages. So far it looks very good.
Best group .202 moa and recoil in very manageable. I ended up with a 1:10 twist and very happy with the out come.

Rick in OR
I rec'd the 14" SSK Bbl with the front 9" turned down to .55" and wanted to use the barrel with a forearm designed to enclose the barrel's deficit.
As a single shot the heat buildup within the forearm is minimal. It is free-floated internally and has no contact to the wood other than a single mounting dovetailed escutcheon.