Could I rechamber a 243Win to 6mmBR or 6mmDasher?

bobnob · Jul 15, 2019

So I’ve lucked into a Howa Stainless 243Win with a 22” sporter profile barrel in a nice trade.

I don’t need another 243. Can I get some advice on whether it is feasible to get a good gunsmith to ream and rechamber this barrel to 6BR or 6Dasher?

I know it will need the chamber end of the barrel shortened and threads cut. I also know I’ll lose a little barrel length.

Just interested to know if it can be done and looking for any advice?

350JR · Jul 16, 2019

While a set-back and rechamber are entirely possible, I would wonder what you wish to do with it.

I'm not entirely positive but I think the Howa is a 1-10 twist barrel. If planning on shooting long range targets I'd check into the twist rate required for your bullets of choice.

The heavy for caliber bullets MIGHT shoot ok (but I'd be surprised) but they would not be stable for long range shooting. I do not know where the line is for twist / bullet rates for sure but it seems I recall 10 twist was recommended for 90 grain and lower.

This NOT my wheelhouse though so I'd check on the target forums on the accurateshooter site.

I could be not recalling it all exactly correct But looking at barreling a rifle for 6BR for myself to play with, the faster twist rate barrels were highly recommended even though my own use would be close to middle range deer. When or if it came time to SELL my rifle, should I go with it.....it would be a tough one to sell with a slow twist rate........(I was told.)

Have fun and shoot safe.
God Bless
Steve

bobnob · Jul 17, 2019

G’day Steve,

You’re right it is a 1-10”

I was thinking 80-90g bullets for mid range plinking, foxes, goats and possibly the odd pig or deer.

I may well rebarrel it yet and see if someone wants a replacement 243 barrel, or just store it for a rainy day. Or perhaps I might still go ahead and rechamber in 6BR.

I haven’t shot this “donor” yet so won’t decide either way until I’ve tried that.

Many thanks for your thoughts!

- Bob

26NosFan · Jul 18, 2019

Do a 243 AI or send to JES and make it a 358 Win.

Dwh7271 · Jul 18, 2019

I’d think you could with shortening it a bit.
243 is around .452-.453 at the base of the shoulder, Dasher is .459.
With the improved shoulder on the Dasher it should be ok to run a reamer up in there and with the shortened chamber, be ok to set headspace.
I’d probably lean Dasher because of that versus 6 BR but just my opinion.

bobnob · Jul 20, 2019

I’m going to discuss it with my gunsmith - at this stage I’m thinking I’ll go ahead just for the fun of it. It shouldn’t cost much and should be an interesting way to experiment with a new cartridge.

Seems like I’ll end up with about 21” of barrel length. Leaning towards the 87 Berger, 87 Vmax, 90 ELDX or the 90g BT depending on how they all shoot. Do you all think speeds in the realm of 2950fps are possible?

Anyway if and as the project goes ahead I’ll update!