Freebore for 7mm 180g Scenars

[kyreloader]

Trying to figure out the freebore on a 7mm reamer and was wondering if the .188 freebore for the 180 Hybrids would also work well for the new 7mm 180g Scenars.

Now I just have to decide between the straight .284 Win or the .284 Shehane (I have and reload for both).

So what says the forum, .188 freebore ok for either chambering for either the 180g Hybrid or Scenar???

Thanks.

 

[Laurie]

I can't tell you what FB you'd need, but in my chamber the CBTO reading is 0.012" longer for the 180gn Scenar than for the same weight Berger VLD with both the same amount into the lands and measured with the same callipers / comparator. So, that'll give you a 'feel' for it if you've previously used the Berger VLDs (both 168 and 180 are the same up front, only vary in the length of the middle bearing section).

I've not used the Hybrid, but a bit longer than the VLD in this respect?

 

[Jay Christopherson]

I would consider a much longer freebore for that bullet - in the .250" range at least. Particularly if you choose the Shehane.

 

[kyreloader]

I am under the impression that .188 is the FB for the Hybrids with .220 for the VLDs. I could be wrong.

I am glad that I raised the question it seems.

 

[Steve Blair]

I believe it will need ~.100" more freebore than the 180 Hybrid. Since the Hybrid needs .200" or more to clear the junction with a jump, it should be .300" or more. Here is a QuickLOAD CSV line for the bullet file, for those so inclined. [br]
".284, 180, Lapua Scenar-L G7 #GB553 ","180","1.490","5.95","7.21","5.65","G7","2",".284",".280",".280","","","","","","","","","","25"

 

[bsumoba]

so here is my reamer print...what is my freebore? im assuming the .188 correct?

im waiting for my rifle to finish, then I'll do my actual measurements. If need be, I'll get a 7mm uni-throater to open my freebore.

just curious why PT&G (David) would recommend a ".188" when most guys on here have longer FB.

 

[Steve Blair]

Dave likes to keep the freebore to minimum to maximize throat erosion distance. My experience is that the barrels stop shooting well before I run out of throat. I would start with a freebore around .200-.210".

 

[kyreloader]

Thanks Steve, now I am really confused. It is looking like .200-.220 might be what I need. Plan on calling to order my reamer soon, so any additional input would be appreciated.

Thanks.

Wade

 

[Steve Blair]

Wade, [br]
I started with .220" for my Shehane, then had it shortened to .188" and should have left it alone. I subsequently bought a Uni-Throater with 7mm and caliber .30 reamers. Now, I can set the throat to whatever is needed. Doing it again, I would either stick with .220" or order a 0 freebore reamer and do it myself. Properly used, Uni-Throaters deliver an excellent leade finish, better than I have ever seen with a chamber reamer. [br]
Just buying a reamer, anywhere between .200" and .220" should work well for 180 Hybrids. If you want to ensure clearance for the 180 Scenar-L, you'll need to extend it. The !80 Scenar-L has a long bearing surface and relatively short ogive.

 

[Alex Wheeler]

I just had a 284 Shehane reamer made. I sent JGS a dummy with the 180 Hybrid where I wanted it. It spec'd out at .225" The vld needs about .080" more than the Hybrid. Its my opinion that in the 284 you have to pick what bullet you wan to use as there is no freebore that will work with the hybrid and vld. Dave at PTG always seems to recommend much too short of a freebore in my opinion. Its not just about clearing the doughnut, its about keeping the shank of the bullet in the sized portion of the neck.

 

[kyreloader]

Steve, thanks again.

I also have a bunch of the 177g Cauterucio's, do you have any idea where they stand in regards to what FB they need?

Thanks for the comments.

Sounds like I will just send in a dummy round and be done with it.

(zfast-what was the turn around time for your reamer?)

 

[Steve Blair]

I've never shot them. I think Tony Robertson (TonyR) has. You might ask him.

 

[Erik Cortina]

I have shot about 1,000 of the 180 gr. 7mm Scenar L's and if I wanted a do all reamer I would go with a .230" - .240" freebore. I shoot Scenars exclusively and I extended my throat to .300" but I think .280" would be about optimum.

 

[TonyR]

Steve, thanks again.

I also have a bunch of the 177g Cauterucio's, do you have any idea where they stand in regards to what FB they need?

Thanks for the comments.

Sounds like I will just send in a dummy round and be done with it.

(zfast-what was the turn around time for your reamer?)

I shot a lot of 177gr Cauterucios with my Shehane reamer. The freebore is .225 inches. It worked fine for the longest 180 VLDs and the shortest 180 Hybrids (Bearing Surface Length) that I have had.

 

[Alex Wheeler]

JGS is 6 weeks out and their customer service and communication skills are superb. You can see the difference in the reamer quality. The extra $40 is worth it.