Gunsmithing Custom Chamber Reamer questions

[dragonjr45]

Ok guys, this is probably way over my head, but I was thinking about having a PTG reamer made for my upcoming rifle build. It would just be a 7mm/300 WSM with .314" neck. However, the rifle will be using a Seekins WSM DBL that allows a max cartridge oal of 3.14". I was want to set it up to were I could load a berger 180 VLD at 3.100" and have it just touching the lands. Can I simply make 4 or 5 dummy rounds and measure the OAL to the major diameter of the bullet (where the bullet first contacts the lands) and simply subtract the Max Case Length to get the appropriate amount of freebore?

Like I said, I am probably way in over my head, but if I'm building a custom rifle, I'd like to have the chamber setup just right for max magazine length cartridges.

 

[GasLight]

Re: Custom Chamber Reamer questions

Why not just call Dave Kiff and tell him exactly what you wrote here and see what he says?

He is a great guy, easy to work with and knows his stuff. He will be able to make a blueprint and email it to you just based on what you are talking about.

Dave

 

[Hateca]

Re: Custom Chamber Reamer questions

Yeah call Dave. He call tell you all about your cartridge and the reamer you need off the top of his head. He has some good info.

 

[dragonjr45]

Re: Custom Chamber Reamer questions

Sent PTG my questions via there website questionaire and he recommended .188fb (1°-30 lead). I can't remember if I specified that I would be using a seekins DBM or not.... I think I probably did though.

Thanks guys

 

[wnroscoe]

Re: Custom Chamber Reamer questions

On my 7/300wsm the COAL length is 3.140" with the 180 Bergers +.015" in the lands. My reamer free Bore is .170" and it's a PTG Reamer, .315" Nk. You'd need to shorten the Free Bore slightly to load at 3.100" and have room to chase the lands. My rifle has an internal box magazine and the rifle was built on a LA 700.

Call Dave with these measurements and he'll help you with the correct dimensions. Just an FYI, he has my reamer print on file in case you need it.

 

[dragonjr45]

Re: Custom Chamber Reamer questions

Wnroscoe.... exactly the type of info I was looking for. And in fact, that is about the exact seating depth to Jam I was thinking about, but was just going to shorten it a bit to ensure Magazine compatibility. I think I will get a .140" freebore, which would put a 3.110" coal 180 Berger .015" into the lands, and leave me about .03" to spare in the mag (3.14" mag length). Correct me if I'm wrong, but I should still be able to run 162 AMAXs or 168 Bergers if I chose to and still be to the lands and mag compatible, since surely the 180s have a longer nose...right?

After emailing PTG back explaining that I would be using the Seekins Mag system and the COAL I was wanting to use, they suggested .140" freebore. So that sounds like the magic number for me.

 

[wnroscoe]

Re: Custom Chamber Reamer questions

Yes, you'll be able to run 162's/168's just fine.

66.0 RL25 / WLR Primers / 300 or 270 WSM Brass / 2,900ish fps

.............It Hammers

 

[dragonjr45]

Re: Custom Chamber Reamer questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">Yes, you'll be able to run 162's/168's just fine.

66.0 RL25 / WLR Primers / 300 or 270 WSM Brass / 2,900ish fps

.............It Hammers </div></div>

Is that with the 180s? If so, that is a hammer! Whats barrel length?
I was thinking I would start out with some Retumbo or even H1000. Hodgdon got me with their temp. stability

 

[dragonjr45]

Re: Custom Chamber Reamer questions

Also, do you a 7 WSM or 300 WSM seater die? I'm torn there.

 

[wnroscoe]

Re: Custom Chamber Reamer questions

That load is with the 180's. I use a modified wilson inline seat die and arbor press for seating. For press work use the 7wsm Redding Comp Seat Die

 

[dragonjr45]

Re: Custom Chamber Reamer questions

180 berger at 2900fps is smokin. What barrel length. I assume 1 in 8" twist is best for 180s?

 

[USMCj]

Re: Custom Chamber Reamer questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dragonjr45</div><div class="ubbcode-body">180 berger at 2900fps is smokin. What barrel length. I assume 1 in 8" twist is best for 180s? </div></div>

The 180's are happy between 2950 and 3150fps, and 1/8 is too fast IMHO, 1/8.5 to 1/9 will work with the 180 Bergers.

 

[wnroscoe]

Re: Custom Chamber Reamer questions

1-9 Finished at 27" with a brake.

H1000 was giving velocities of 2,950fps but accuracy wasnt as good as RL25.

I built a 7mmSAUM for a guy on the left coast. 180's at 2,950 in his rifle. 1-9 26" Rock Barrel

 

[USMCj]

Re: Custom Chamber Reamer questions

William, the guys over at Rock recommend 1/8.7 for the 180's, any reason you are going with a 1/9?

 

[dragonjr45]

Re: Custom Chamber Reamer questions

Being as I can only get "standard" twist rates in a Krieger 5R, I guess I'll go with 1 in 9" twist. Should be safe at 2000ft.