338 Lapua Improved 40 degree with print. Which design is better?

[Despotes]

I placed an order for a 338 Lapua Improved 40 degree reamer. I know there are many slight variations with this design and would like to know if this particular reamer is of the higher performing or lower designs compared to others. Any experts that can tell me?

Thanks

 

[Despotes]

Bartlein offers a "Deep chambering" service. Is this recommended for using 300gr for max powder cap.? Is this the same as Weatherby's "freebore"?

 

[yorke-1]

It will depend a little on whether this rifle is a single shot or repeater. If it's a repeater then I'd leave it alone. I doubt that changing any dimension of the brass would offer a significant improvement in performance. Changing the throat/freebore would make a difference but may limit you to running it as a single shot to take advantage of the increase in capacity.

Andrew

 

[Despotes]

I have no problem running it as a single shot if I can get better performance and versatility. I want to run the Berger Hybrid 300gr at around 3000 fps and don't want to be hamstrung with a shorter throat.

 

[Pdvdh]

I would at least change the design to reduce dimensions G and I from 0.3398" to 0.3385". No sense allowing the excess gas to excape around the bullet as it travels thru the "LEAD".
If you're going to outside neck turn the necks of your brass casings, you may want to reduce the dimension H from 0.372 to 0.370".
And as yorke-1 stated, determine your preferred cartidge overall length (COAL) with the bullet you intend to shoot, and then match the "LEAD" length to be compatible with your preferred COAL. Your "LEAD" dimension is shown as 0.130". I went with 0.225" "LEAD"
on my reamer design, intending to load the Berger 300gr OTM to a COAL of ~3.945".

 

[Despotes]

I would at least change the design to reduce dimensions G and I from 0.3398" to 0.3385". No sense allowing the excess gas to excape around the bullet as it travels thru the "LEAD".
If you're going to outside neck turn the necks of your brass casings, you may want to reduce the dimension H from 0.372 to 0.370".
And as yorke-1 stated, determine your preferred cartidge overall length (COAL) with the bullet you intend to shoot, and then match the "LEAD" length to be compatible with your preferred COAL. Your "LEAD" dimension is shown as 0.130". I went with 0.208" "LEAD"
on my reamer design, intending to load the Berger 300gr OTM to a COAL of ~3.945".

There's little I can do with the reamer. I already have it. The only thing I can do is have Bartlein extend the throat/lead (throat reamer?) by roughly .060" to .080". Right?

 

[Pdvdh]

I see. I didn't realize the reamer was already purchased. I don't know if it's possible to have the reamer reground to smaller dimension or not, and I don't know what sort of fee would be charged. But with respect to the "LEAD", yes the only alternative I can think of is the use of a .338 neck/throat reamer to lengthen the "LEAD". That steel has already been removed from your reamer, and there's no way to add it back to lengthen your "LEAD" with that reamer.

I have heard of re-sharpening services that aren't all that expensive from reamer manufacturers, but I don't know what might be possible to alter your reamer dimensions before you cut your barrel chamber with it. Now's the time to do something like that rather than rushing into a chamber job with a reamer that's lacking in any significant way. It only gets more and more expensive once you've cut and headspaced your barrel's chamber.

 

[Despotes]

I see. I didn't realize the reamer was already purchased. I don't know if it's possible to have the reamer reground to smaller dimension or not, and I don't know what sort of fee would be charged. But with respect to the "LEAD", yes the only alternative I can think of is the use of a .338 neck/throat reamer to lengthen the "LEAD". That steel has already been removed from your reamer, and there's no way to add it back to lengthen your "LEAD" with that reamer.

I have heard of re-sharpening services that aren't all that expensive from reamer manufacturers, but I don't know what might be possible to alter your reamer dimensions before you cut your barrel chamber with it. Now's the time to do something like that rather than rushing into a chamber job with a reamer that's lacking in any significant way. It only gets more and more expensive once you've cut and headspaced your barrel's chamber.

I didn't know my reamer was a relatively bad design. I wouldn't have bought it if I had known that.

 

[Pdvdh]

I didn't know my reamer was a relatively bad design. I wouldn't have bought it if I had known that.

Your reamer will work. I think it has looser dimensions than ideal for a guy that's going to run an Improved version of any cartridge, because if you're going with an Improved version it infers to me you're looking to refine and maximize cartridge performance and accuracy.

I don't design and manufacture chamber reamers, but I've learned that the folks that try to improve upon factory chambers would reduce the "LEAD" diameter to 0.0005" over bullet diameter.

Not trying to be a jerk. I thought you were seeking advice prior to ordering your reamer. Perhaps your reamer supplier will exchange your's for a slightly different spec'd reamer. Or maybe you're happy with your current reamer.

About 6 months ago I researched reamer deigns for an Improved .338 Lapua fairly extensively. Below is the reamer I specified and ordered. Doesn't mean it's the world's best ever .338 Lapua Improved reamer design. But it does duplicate many of the reamer features and specifications I found other gunsmiths ordering.

 

[Despotes]

Your reamer will work. I think it has looser dimensions than ideal for a guy that's going to run an Improved version of any cartridge, because if you're going with an Improved version it infers to me you're looking to refine and maximize cartridge performance and accuracy.

I don't design and manufacture chamber reamers, but I've learned that the folks that try to improve upon factory chambers would reduce the "LEAD" diameter to 0.0005" over bullet diameter.

Not trying to be a jerk. I thought you were seeking advice prior to ordering your reamer. Perhaps your reamer supplier will exchange your's for a slightly different spec'd reamer. Or maybe you're happy with your current reamer.

About 6 months ago I researched reamer deigns for an Improved .338 Lapua fairly extensively. Below is the reamer I specified and ordered. Doesn't mean it's the world's best ever .338 Lapua Improved reamer design. But it does duplicate many of the reamer features and specifications I found other gunsmiths ordering.

You're not sounding like a jerk. I wanted constructive criticism about the reamer I bought. I assumed JGS would have had a decent design.
I don't know why G and I are so far off from other prints I just recently viewed today. It looks more like a defect.
I avoided using Pacific Tool because of a lot of negative reviews. Has their service improved recently?
I'll try to return it Monday. It's too bad because it was the last one they had in stock.
How is your Lapua Improved shooting? 300Gr Bergers? Maybe I'll use your print if I can return my reamer.

 

[yorke-1]

There's nothing wrong with your reamer. As it sits you'll have a chamber which will allow you to run as a repeater and still offer a significant improvement over the standard lapua. Youll be able to simply shoot loaded 338 lapua ammo in the chamber to form brass if that's what you want to do. You won't need to neck turn brass, which is always annoying. And you own the reamer, so when you burn up this barrel you can have another cut to the exact same specs.

I've designed a few reamers of my own and done things like tight necks, extended leades, and custom leade angles. They made the reamer uniquely mine but they didn't make it significantly better than any others out there.

Chamber up a barrel, shoot it till the rifling is gone, and then do it again!

Andrew

 

[Pdvdh]

I'm still awaiting a McMillan stock for my build. Also some action work. So I don't have my rifle completed yet.

PT&G gave me some round-about, which concurred some rumors I had heard prior to placing my order with them. I don't think there's any ill will involved. Just too much happenstance. You need to check and recheck your order in the effort to confirm things don't fall thru the cracks and to minimize misteps along the way. I do think they could use some improved QA/QC with their order intake, processing, manufacturing and shipment execution, in order to reduce the number of needless speed bumps in their process...

 

[Pdvdh]

FYI, here's two of the .338 Lapua Improved reamer spec sheets I reviewed prior to ordering my own reamer. I looked at more. Still have these two on my computer. These both have 40* shoulders. I decided on a 37* shoulder. I don't think it makes much difference in cartridge performance.

 

[Despotes]

There's nothing wrong with your reamer. As it sits you'll have a chamber which will allow you to run as a repeater and still offer a significant improvement over the standard lapua. Youll be able to simply shoot loaded 338 lapua ammo in the chamber to form brass if that's what you want to do. You won't need to neck turn brass, which is always annoying. And you own the reamer, so when you burn up this barrel you can have another cut to the exact same specs.

I've designed a few reamers of my own and done things like tight necks, extended leades, and custom leade angles. They made the reamer uniquely mine but they didn't make it significantly better than any others out there.

Chamber up a barrel, shoot it till the rifling is gone, and then do it again!

Andrew

The G and I specs are larger than all other .338 prints I've seen today. Most if not all are .3385. Isn't .3395 too large permitting excessive blow by as phorwath mentioned?