THIS Is the Dedicated 65G Bullet I Want

[Variable]

Of course, there's also the question of whether or not the polymer tips can be removed from TAC-TX bullets without damaging them.

If they are hard to pull out without tip damage, then it might be better to drill through the base of the bullet to hit the bottom of the cavity. With the cavity exposed, a thin punch could be used to pop them out from the inside.

[stanc]

Here's an idea for consideration:



1. Chuck .308 TAC-TX bullet base-first in lathe collet.
2. Turn down the front end (ahead of the crimping goove) to 0.264" diameter.
3. Remove bullet, turn it around and put back in collet nose-first.
4. Turn down the base to 0.264" diameter, and machine boat tail.

New crimping groove need not be machined, since these bullets are solely for testing, not production.

===========================

However, the above approach might not be feasible, for a couple of possible reasons.

First, I don't know if the nose walls are thick enough to permit reducing the OD from 0.308" to 0.264"

Second, I don't know if the main body is long enough to hold it in the lathe collet.

If the answer to each of those two questions is "Yes," then this approach would have a number of advantages over the other ideas presented to date:

- Simplified machining.
- No modification to ogive required.
- No modification to internal cavity required.
- Usable polymer tip already installed.

Comments? Criticisms?

[sneaky one]

Good point stan, this may be a problem child... The Gmx is looking better all the time.,,, That tip may be a pain to even have it injection molded- so pointy it is- worth alook tho.I am to change the frontal of a Gmx here- I found a few in the safe,,, I'll pic it up asap.

[Variable]

Here's an idea for consideration:



1. Chuck .308 TAC-TX bullet base-first in lathe collet.
2. Turn down the front end (ahead of the crimping goove) to 0.264" diameter.
3. Remove bullet, turn it around and put back in collet nose-first.
4. Turn down the base to 0.264" diameter, and machine boat tail.

New crimping groove need not be machined, since these bullets are solely for testing, not production.

===========================

However, the above approach might not be feasible, for a couple of possible reasons.

First, I don't know if the nose walls are thick enough to permit reducing the OD from 0.308" to 0.264"

Second, I don't know if the main body is long enough to hold it in the lathe collet.

If the answer to each of those two questions is "Yes," then this approach would have a number of advantages over the other ideas presented to date:

- Simplified machining.
- No modification to ogive required.
- No modification to internal cavity required.
- Usable polymer tip already installed.

Comments? Criticisms?

Might be worth a shot. If shooting it into gel (definitely not for accuracy), it might work well. I looked a bit for some of them the other night, and they were out of stock everywhere I could find.

[txgunner00]

Here's an idea for consideration:
.....

- Simplified machining.
- No modification to ogive required.
- No modification to internal cavity required.
- Usable polymer tip already installed.

Comments? Criticisms?

Would running it through some swaging/ sizing dies be an option? Probably couldn't do it in one pass and I don't know how the sections in the ogive would react but it might be easier than machining. Just thinking out loud...

[stanc]

Might be worth a shot. If shooting it into gel (definitely not for accuracy), it might work well.

Well, it isn't really necessary to do accuracy testing at this point, just demonstrate minimum expansion velocity and ascertain if the bullet would hold together after impacting the gel block.

I'd also thought it could be used to measure BC, but it later occurred to me that after reducing the diameter and machining a boat tail, weight would probably be significantly less than 100 grains.

I looked a bit for some of them the other night, and they were out of stock everywhere I could find.

Yeah, I read on another forum that .300 BLK TAC-TX ammo is usually available, but the bullets themselves are nearly impossible to find.

This may be an example of the proverbial, "You can't get there from here."

[stanc]

Would running it through some swaging/ sizing dies be an option? Probably couldn't do it in one pass and I don't know how the sections in the ogive would react but it might be easier than machining. Just thinking out loud...

That's an interesting thought. I know that Buffalo Arms offered 5.45x39 cartridge cases made from swaged down .30 Remington brass cases, but I have no idea if solid copper bullets can be reduced in diameter via swaging.

[BluntForceTrauma]

Yesterday the girl at the front desk called and said I had a package. Went and found a delivery from MidwayUSA, 50 Hornady 6.5 120 GMX bullets. These will be prototype fodder for the High ballistic coefficient, High velocity, Low eXpansion threshold bullet project, henceforth dubbed Project H2LX.

[sneaky one]

John, can you start a part 2 on this - separate thread. My pic is stuck in my album- the virus won't let me do 3 things. I have my son back on this- should be fixed by tomorrow- Pull it out and post it if you can.

[stanc]

Yesterday the girl at the front desk called and said I had a package. Went and found a delivery from MidwayUSA, 50 Hornady 6.5 120 GMX bullets. These will be prototype fodder for the High ballistic coefficient, High velocity, Low eXpansion threshold bullet project, henceforth dubbed Project H2LX.

Cool. I look forward to seeing how it goes.

[Bigfoot]

My pic is stuck in my album-

Woah, nice work Sneaky.

Can you post a pic of the nose cavities. How much does the GMX based one weigh? The TTSX based? What tips are these.

You deserve an attaboy. So....Attaboy!

[Bigfoot]

S, have you examined the 127 LRX yet? E-tips too. Curious how you think the ogives world work for this project. A new Cabaela's opened close by a couple weeks ago, haven't been there yet but I'll bet they are stocked. I could try to find a box of what ever you need and mail you some.

[stanc]

S, have you examined the 127 LRX yet? E-tips too. Curious how you think the ogives world work for this project.

E-Tips have a relatively small caliber, tangent ogive. Can't possibly achieve the high BC desired by Hanka and Variable.

LRX appears to have a larger caliber, tangent ogive. Should enable better BC than the E-Tip, but likely not the best possible.

GMX has a secant ogive similar to that in Hanka's proposal. Might be very close to maximum possible BC.

The photo below shows LRX, GMX, and E-Tip bullets side-by-side, for a good comparison of ogives. These are .277 bullets, but nevertheless representative. To see .264 bullets, check the photo in post #53 of this thread.





AFAIK, none of the three bullets (LRX, GMX, E-Tip) will expand anywhere near as low as 1400 fps, so other than getting an approximate BC of the idealized 100gr bullet, I'm not sure what the goal is for modifying GMX projectiles. Unless the plan is to remove the polymer tips and bore out the cavity in order to test minimum expansion velocity?

[Bigfoot]

Unless the plan is to remove the polymer tips and bore out the cavity in order to test minimum expansion velocity?

AHEM:



Doesn't matter how the original bullet expanded, gilding or pure copper. If you control the nose cavity you control the terminal performance.

Thanks for the info on the others, Sneaky likes the GMX and it'll work with the correct tip.

BTW Stanc, couldn't agree more on reducing the diameter of the .308 110 Blackout bullet for testing. Great idea. Course it's new velocity is several hundred FPS faster than the Blackout and it's structural integrity has been reduced by turning it's diameter down so.. That's why I recommended doing the same with the 95 gr 6.8 TTSX and testing it also. The long nose isn't there but the amount of copper surrounding the nose cavity might be about right. Bet you could acquire some 6.8 TTSX's for dissection, measure the wall thickness around the cavity, drill the cavity in the GMX to achieve the same wall thickness and then reduce the diameter of the Blackout bullets poly insert to fit that cavity.

It's going to be tough for anybody other than a manufacturer to R&D the perfect nose cavitity because we don't have access to various sized tip inserts. I applaud the audacity of our members. Gonna be lots of trial and error. Could get spendy. Let me know if I can help offset that or provide materials. Would be real nice if we could acquire the 110 Blackout tips from Barnes and adjust the diameter of the insert until nirvana is found. Worth an email request.

[Bigfoot]

It's late and I gotta work early. If anyone can dig up pics of sectioned 110 Blackout and 95 gr 6.8 TTSX please post them.