Reamer profiled to bullet profile

[borderghost]

In the clouds on this subject , maybe someone can add some light, If you are using the same bullet all the time is there anything that you can do to your reamer to have it ground to the profile of your bullet to make a smoother transition into the rifling and have your free bore matched to the bullet , so your bullet would be down half way in the neck.
Thanks for taking time to read this and add your thoughts and experience .

 

[Dave Marshall]

You can have reamers ground to whatever specifications you want. You just have to pay the toolmaker to make a custom reamer.
Depending on what you’re asking for, they might be able to make modifications to an existing design or may have to start from scratch.

 

[DaveTooley]

If I understand you correctly you want to adjust the freebore length to get a bullet seated at a specific depth in the case. The answer is yes it's done all the time. As to matching the ogive profile. No we don't. One reason is the complexity and cost to grind a radius leade. The other, any leade changes/wears as the round count go up.

 

[MGYSGT]

You can't ream a chamber to fit the ogive of the bullet. That would require the bullet to squeeze through a smaller whole than the barrel.

 

[Herzo]

An ogive radius would act to increase the resistance to the transition of the bullet to the lands of the barrel thereby substantially increasing the initial pressure pulse.

 

[linebaugh]

It would begin to errode the throat and that pretty ogive that matches the bullet will soon match nothing. Dont reinvent the wheel, spend money on loading better.

 

[BOB LEE SWAGGER]

Make it easy for yourself: https://www.jgsprecision.com/pages/jgs-custom-reamers-gauges

 

[WayneShaw]

Many years ago, I was talking to Kiff, and he was pushing having the leade ground to match the bullet ogive. I declined and have hardly ever heard of it again. I agree that the leade is going to wear in regardless of ogive.

 

[Tim Singleton]

Do some reading on bore rider reamers

 

[DaveTooley]

I'll probably never get around to doing this but I've thought about how I could measure changes as the leade erodes. I was going to use a tenth indicator and measure the changes in the Z axis in relation to the X axis. Lots of setup time and wouldn't change a thing.

 

[Alex Wheeler]

The lead does wear into the shape of the bullet. Probably not exactly but it does wear that way. I have reamers with the ogive radius ground as well as ogive matching angles. Theres so many different applications so I cant make a blanket statement about what I know so far other than a 1.5 degree lead works very well for a lot of different bullets and it does not have any "weirdness" about it.

 

[Tokay444]

I'll probably never get around to doing this but I've thought about how I could measure changes as the leade erodes. I was going to use a tenth indicator and measure the changes in the Z axis in relation to the X axis. Lots of setup time and wouldn't change a thing.

It’s much easier to drop a sphere into the leade and use a depth mic.

 

[DaveTooley]

It’s much easier to drop a sphere into the leade and use a depth mic.

That will give you the erosion in one place. It won't tell you anything about the change in the shape. I guess you could use multiple gage balls and plot the change as the round count increases.

 

[gunsandgunsmithing]

I've been giving thought to having the 45° end of chamber neck made to 15°. It will cost a little freebore and my thoughts are not that it will shoot any better or worse than what we are use to. Rather, it would be about turbulence and bbl life.

 

[Edd]

I've been giving thought to having the 45° end of chamber neck made to 15°. It will cost a little freebore and my thoughts are not that it will shoot any better or worse than what we are use to. Rather, it would be about turbulence and bbl life.

Some cartridges already deviate from that 45° transition angle. I have a 35 Whelen that is 30°. SAAMI for a 7x57 is 15°. I'd guess there are many others that I'm not familiar with.

 

[Bamban]

I've been giving thought to having the 45° end of chamber neck made to 15°. It will cost a little freebore and my thoughts are not that it will shoot any better or worse than what we are use to. Rather, it would be about turbulence and bbl life.

Here you go, I did one back in 2018. The effective freebore is 0.140. The print shows what's left after the 45 degrees was laid down to 10.

We are launching 85.5s from 20 inch service rifles at some decent velocity. The freebore enabled the boat tail above the neck, thus freed enough boiler room.



Could not find some chrono data with 85.5s, I found this on 80 VLDs. Barrel had a few rounds, I chased it with the 10 degree .140 freebore. The ES surprised us, the group was way under a minute at 200. Could not find any pictures. This was a screenshot from the text I sent to one of the high power shooters in 2019, I believe



I believe Dave Manson designed one last year for the 85.5s. His version has 15 degrees.

 

[LVLAaron]

@Bamban - What's kind of speeds were you getting?

 

[Bamban]

@Bamban - What's kind of speeds were you getting?

In the same range as the the 80 VLDs, little over 2800. Average retained velocity at 1000 on Shotmarker shows a little over 1300.

 

[LVLAaron]

In the same range as the the 80 VLDs, little over 2800. Average retained velocity at 1000 on Shotmarker shows a little over 1300.

Mmmm cool! Going to grab one of those reamers.