Why increase the freebore on 243?

[urbanrifleman]

When using the 108-105 VLDs, why do you increase the freebore?

 

[dminn1]

Some like a longer freebore with these bullets to let them seat the bullet with the bearing surface above the neck/ shoulder junction in the case. This lets them avoid brass build up that can occur in this area often called a doughnut. This constriction in your case neck can cause problems with neck tension when your bullet is seated below it. Another benefit to a longer freebore is increased case capacity that can result from seating the bullet further out of the case. The 105g class of bullets are long for caliber so increased freebore can help with both of these situations when using them in the .243.

 

[Eric Leonard]

I had 2 barrels done in 243 on a min SAMMI reamer,,one I had throated out so the 105 VLDH seated with all the bearing surface above the NSJ,,the COAL was 2.865. that bbl shot the 105 VLDH at over 3200 fps with 42 gr H4350 and would stay on my 5.5"x 8" plate at 1,030 yards with no problems at all,,it was the best shooting 1,000 yard bbl I have had to date,,

I left the other bbl throat alone and it shot the light varmint bullets well but with the 105 VLD loaded at 2.625 would max out at 2990 at 39.5 grs H4350 and was at best a 1 moa bbl with the 105 class bullets,,

 

[Shawnba67]

I have a 30" 7 twist sammi 243 chamber and get a touch over 3200fps with 4831sc and 105rdf's
I have trouble with doughnuts and my next chamber will be throated to keep me out of them.

 

[urbanrifleman]

I had 2 barrels done in 243 on a min SAMMI reamer,,one I had throated out so the 105 VLDH seated with all the bearing surface above the NSJ,,the COAL was 2.865. that bbl shot the 105 VLDH at over 3200 fps with 42 gr H4350 and would stay on my 5.5"x 8" plate at 1,030 yards with no problems at all,,it was the best shooting 1,000 yard bbl I have had to date,,

I left the other bbl throat alone and it shot the light varmint bullets well but with the 105 VLD loaded at 2.625 would max out at 2990 at 39.5 grs H4350 and was at best a 1 moa bbl with the 105 class bullets,,

My Saami 243 Bartlein 5R will shoot under .5" and its an AR10. I think 2900 is plenty with the Berger 108.

 

[urbanrifleman]

I can see having a 130 freebore with a 6 BR that has a very long neck, but the 243 does not have half the neck of a 6BR. If you put the bullet out past the donut that bullet is barely going to be set in the case.

 

[XTR]

I can see having a 130 freebore with a 6 BR that has a very long neck, but the 243 does not have half the neck of a 6BR. If you put the bullet out past the donut that bullet is barely going to be set in the case.

In an AR platform you are probably correct. In other applications you can run them at over 3100FPS, and that is an advantage. (Beauty of the 6SLR, you get a long neck and pretty much the same velocity potential)

 

[AckleymanII]

I have a 30" 7 twist sammi 243 chamber and get a touch over 3200fps with 4831sc and 105rdf's
I have trouble with doughnuts and my next chamber will be throated to keep me out of them.

Prepare yourself for very short barrel life.

Pick

no doughnut issue or longer barrel life(deal with doughnuts)

Also, do you ever re turn necks? This is a shore nuff shock as you measure brass flow into the neck.

Barrels can be set back, maybe

Mr Big's experience mirrors my own, but always remember, barrels are individuals and wreak havoc on my thinking at times. When fitting reamer pilot bushings to various barrels, it is all to obvious that bores can vary dramatically. Gunsmiths never tell what size reamer pilot they used in the throat, nor how the muzzle dia pilot may increase/decrease from the throat Pilot(dimension).

More neck clearance maybe in order as necks thicken at the shoulder, not allowing consistent bullet release, and 243 Win is one of the worst. Do your due diligence. I was having this conversation with a very experienced Sling shooter recently, and he recommended to me to to run a K&M expander through the neck.

I despise short barrel life almost as much as I hate doughnuts.

 

[Shawnba67]

Prepare yourself for very short barrel life.

Pick

no doughnut issue or longer barrel life

Barrels can be set back, maybe

I am not seeming to get what your trying to say?
Are you implying that another .100 of freebore will destroy barrel life?

 

[AckleymanII]

Well.........

My bolt guns have a "sweet spot" where they shoot amazing. Get too far out of that "sweet spot" and accuracy starts to deteriorate, you have to choose your Poison. Various bullets have their own mind in what they like.

 

[Eric Leonard]

if I was happy at 2900 with 105s I would not be shooting a 243 size case,,

 

[urbanrifleman]

In an AR platform you are probably correct. In other applications you can run them at over 3100FPS, and that is an advantage. (Beauty of the 6SLR, you get a long neck and pretty much the same velocity potential)

3.59 MOA verses 3.96 MOA at 600 10MPH full value 90 degree wind at 600 yards.

If you could even call that an "advantage"... but I understand that "more better" is always "better" these days. I would argue the lower accuracy node would shoot better in the long run, the barrel stay cooler through the match, and the barrel would certainly last longer (as well as the brass). But I also understand that I am in the minority I suppose.

 

[urbanrifleman]

if I was happy at 2900 with 105s I would not be shooting a 243 size case,,

And if I were shooting for 3100fps and 3200fps I wouldn't be shooting a 243 either.

 

[XTR]

John Whidden has done pretty well with it. Look him up if you're not familiar.

At 1000 yards it's more pronounced. 6.7MOA vs 7.9MOA, with the 108s. That's 2½ scoring rings difference. Depends on how you use it as to what you need.

 

[urbanrifleman]

John Whidden has done pretty well with it. Look him up if you're not familiar.

At 1000 yards it's more pronounced. 6.7MOA vs 7.9MOA, with the 108s. That's 2½ scoring rings difference. Depends on how you use it as to what you need.

I no way am I trying to be rude, but the ultimate "1000 yard blah blah blah" assumption that everyone every discussion of every shooting subject is a 1000 yard competition in every case is just unbelievably TIRESOME for me personally.

I really doubt, if I were willing to take the time to look it up, that the records, even at 1000 yards, are not held by the fastest round in the competition. Quite the contrary.

 

[urbanrifleman]

In an AR platform you are probably correct. In other applications you can run them at over 3100FPS, and that is an advantage. (Beauty of the 6SLR, you get a long neck and pretty much the same velocity potential)

Ummmm yah!!! He has a 32" barrel too!!!

"John’s primary “Any Sights” .243 is built on a Winchester m70 action, it has a Broughton 32″, 1:8″ twist 5C (canted land) barrel. "

 

[Eric Leonard]

the way the lengthened freebore works out the 105 Scenar is loaded to 2.850 ,,the other case is a 6 BRDX with the 105 VLD,,,,if you want to seat your bullets below the NSJ then have at it but I get better accuracy with the bullets seated above the NSJ and it creates more powder space as a plus,,also my 243 is a Tac 30 repeater in an AICS 1.5 with a 27 inch bbl,,

while it isnt as accurate as my Farley 6BR or 6 BRDX barrels it is easier to hit stuff with at unknown distance and is really easy to shoot compared to the bigger calibers,,

 

[AckleymanII]

I agree, if you seat below the shoulder neck junction, then plan for your problems. For many cases, this is normal because of OAL constrictions on magazines.

Often, when you seat to the shoulder neck junction, you may have .100 leade growth, then you have other problems to deal with, depending on how JUMP friendly your particular bullet design is.

 

[XTR]

Ummmm yah!!! He has a 32" barrel too!!!

"John’s primary “Any Sights” .243 is built on a Winchester m70 action, it has a Broughton 32″, 1:8″ twist 5C (canted land) barrel. "

Which goes back to my original comment

"In an AR platform you are probably correct. In other applications you can run them at over 3100FPS, and that is an advantage."

This site is loaded with long range shooters, and in NRA competition shooting long range starts beyond 600 yards.

 

[KenOath]

When using the 108-105 VLDs, why do you increase the freebore?

I believe the main reason people have longer fb with the 243 and 105-108gn bullets is to keep bearing surface of bullet above neck shoulder junction.