Chamber for .243 to shoot heavies?????

[hdfireman]

I'm getting all the parts together to start my .243 build. I plan on shooting the 105 Bergers, 107 SMK's and maybe the 115 DTACS. I have read that it's best to chamber the barrel specifically for these rounds. What's the forums take on that? What is different about that chamber?

 

[watercam]

I have had two 243s so far and like them. I start with a plain jane SAAMI chamber and see where all those bullets fall at the jump or jam you desire. I found that cutting the throat 0.100" longer worked for all the projectiles you listed. If for no other reason than a tad more powder space (especially with slow powders and 115 gr. bullets). I like a no-turn neck myself but my disciplines are High Power and Long Range.
I use Lapua brass but have had consistent neck cracks on the fourth firing on two different lots of those so I anneal every three firings.
All the best!

 

[hdfireman]

Thanks for the info sir.

 

[jcampbellsmith]

One thought is to make up some dummy rounds with the bullets that you would like to use. Good luck. JCS

 

[Scott Harris]

If you are going to order a chamber reamer, then I'd just talk it over with Dave Kiff at PT&G. For my part, I use his 243WIN Match reamer and it works fine with the 105/107s. The 115s probably require a little more careful consideration of the dimensions, but my "standard" match reamer works great with all the 105s. I agree that a SAAMI minimum chamber and neck dimension is a good place to be. Lapua brass is pretty thick at the neck and produces a loaded round with a .272 neck diameter..or thereabouts. So, a SAAMI minimum neck of .276 would be perfect for a no-turn chamber.

Attached is my reamer print. It calls out a .274 neck, but the correct dimensions are now .275. I had the .274 replaced with a .275 neck reamer....would just go with SAAMI .276 if I did it again.

 

[hdfireman]

If you are going to order a chamber reamer, then I'd just talk it over with Dave Kiff at PT&G. For my part, I use his 243WIN Match reamer and it works fine with the 105/107s. The 115s probably require a little more careful consideration of the dimensions, but my "standard" match reamer works great with all the 105s. I agree that a SAAMI minimum chamber and neck dimension is a good place to be. Lapua brass is pretty thick at the neck and produces a loaded round with a .272 neck diameter..or thereabouts. So, a SAAMI minimum neck of .276 would be perfect for a no-turn chamber.

Attached is my reamer print. It calls out a .274 neck, but the correct dimensions are now .275. I had the .274 replaced with a .275 neck reamer....would just go with SAAMI .276 if I did it again.

Thanks Scot! Great information.