Bullet weight

[MOShooter]

My new 6br barrel has a free bore of .093. Will this be enough space to shoot 107mk without getting into my case too far. Would I be be better dropping to a 90-95gr bullet. At present Ill be shoot 100, 200 & 450yd targets.

 

[Lapua40X]

Forgive me for asking but I want to make certain we're on the same page.
By "free bore" I am assuming you do mean the distance from the case mouth to the rifling. If you're describing something other than that please let us know.
If your 6BR has .093 free bore (as defined above) you will find your 107 MK pressed much too far back into the case. That's really a shame because the 107 MK bullets work very well in my 6BR Norma 1:8 twist out to some impressively long distances.

 

[MOShooter]

Yes that is what I'm talking about. I called criterion today and was disappointed to discover that they reamed it to .093. From what I've read on here it needed to be about .110. I guess that is what I get for going the prefit route. I guess I'll have to sell the 500 107mks that I have and look for something lighter. Is that enough for 90-95gr?

 

[expiper]

Mo,,,I have used .080" FB with great results,,,try a few before you sell them,,,Roger

 

[Lapua40X]

This isn't precisely on center but it may help.
http://www.6mmbr.com/catalog/item/1308478/778744.htm

Also, I agree with expiper. I'd try them before dumping them off but I'd do some data collection with something like Hornady OAL gauge (http://ads.midwayusa.com/product/570611/hornady-lock-n-load-overall-length-gage-bolt-action?cm_vc=ProductFinding) so I have some idea what to expect and know if I was down in the donut area with the seated 107 MK bullet.

 

[Cort]

Do you have a local gunsmith with a throating reamer? Or, will Criterion rethroat your barrel for you?

Cort

 

[Phil]

Do you have a local gunsmith with a throating reamer? Or, will Criterion rethroat your barrel for you?

Cort

This^^^^^^^

 

[MOShooter]

I'll have to check with my smith. If he can what depth should I take it to?

 

[Nomad47]

To be safe, you can have a gunsmith extend the throat to whatever you want. My two Criterion 6XCs didn't have the freebore I wanted, so I bought a throating reamer and extended the throat myself.

 

[fdshuster]

MOShooter: Dave Kiff will most often recommend .104" freebore for the 107 SMK. My first 6BR reamer was done with .104", but at around 1000 rounds fired the bullet was just barely hanging on to the front of the case mouth.

One of my other 6BR reamers has the before mentioned .080" FB and it works fine for both the 105 Bergers #24428 (my most used), and the 107 SMK's.

It won't be very long until that .093" is closer to .100". The long, heavyweights will wash out the throat.

 

[WyleWD]

One of my other 6BR reamers has the before mentioned .080" FB and it works fine for both the 105 Bergers #24428 (my most used), and the 107 SMK's.

It won't be very long until that .093" is closer to .100". The long, heavyweights will wash out the throat.

+1 on Frank's post. Mine is a .080, and while I haven't seen the throat wash just yet, it shoots the 107's and the 95's equally well out to 400yds. I've never had occasion to shoot beyond that distance with either one so won't comment on how well one or the other might do beyond 400yds. So, I agree that you might want to try those 107's before you sell em off. JMHO. WD

 

[bdale]

Mo,,,I have used .080" FB with great results,,,try a few before you sell them,,,Roger

I'm with expiper on this one I have a 6BR with a 85th's free bore and it has shot in the one's for me and my son has shot in the one's with it as well. Shoots most heavies well some better than others ;D

 

[AR Shooter]

If you do decide that you are selling those 107s, please sell them to me.