BOAT-TAILED Gas Check Update/Teaser

[HollowPoint]

I usually wait until I have my project's completed and tested before posting anything about them but, I'm having a hard time containing my excitement about these Gas-Checks.

After completing my third set of Prototype dies I finally hit on the ones that seem to work the best for me.

These are just "Proof-Of-Concept" dies. Meaning; before I get anymore involved with this project I just wanted to make sure I wasn't just chasing farts in the wind.

Two things I've learned so far:

(1) This type of Gas-Check has to be formed in stages otherwise .

My first two attempts at making these specialty dies entailed forming them from copper/brass cups in three initial stages, then a fourth and final separate stage. The first three "Stages" were all integral to the first die and the final forming stage required a separate forming punch. (the fourth stage)

(2) It IS possible to make them out of aluminum as I'd hoped BUT:

The aluminum sheeting I use must be annealed first. In addition; aluminum Boat-Tailed Gas-Checks require a dedicated set of dies. You can't use the same dies for copper/brass and aluminum.

The reason for this is because, I'm using 44 caliber gas checks that I had left over from my 44 cal. reloading days. The diameter of these 44 caliber checks remains the same after the initial forming stages. With the aluminum checks, the initial forming stages reduces the overall diameter which caused the semi-completed aluminum check to fall down into the die.

It can be retrieved and placed manually on the final forming punch but, it's almost impossible to center it perfectly so the final outcome is an exercise in futility.

BECAUSE of the angles that these Boat-Tailed Gas-Checks are formed in, you can't just form them the way you form normal flat based gas checks. That method just rips the little metal disks all to hell.

Also, I wanted the walls of these Boat-Tailed gas checks to go a little higher than the regular flat base gas checks so that after I installed them I could go back and crimp them in place.

With my regular gas checks I've noticed that they don't always stay on the boolit; which effects accuracy. I figure that crimping them on would mitigate this problem.

I still have a ways to go before I even test my first Boat-Tailed Gas-Checked Boolits but, I just couldn't contain myself. I had to let it be known that this was on the horizon.

The things left to do before I can officially get to the range for testing are:

Make my crimping die to crimp on these Boat-Tailed Gas-Checks.

Rather than making an entirely new dedicated bullet mold to accommodate these Boat-Tailed Gas-Checks, I plan on just milling some Boat-Tailed extensions to add to the tail end of my existing bullet molds.

In theory, I'll just add a thin layer of metal to the top of my molds with the beveled shape I need to fill the inside dimensions of the Boat-Tailed Gas-Checks.

I'll be posting some photos of my first few checks and the prototype dies tomorrow some time.

I've had this project in mind for some time now and the main thing that's kept me from getting this far has been the fact that my bench top lathe is anything but accurate.

In order for these gas checks to work properly, everything has to be perfectly aligned. I just haven't been able to get that kind of accuracy up until lately. (still not perfectly aligned but, better than it was)

As most of you guys know, the tail end of our bullets has to be as perfectly shaped (wether flat or Boat-Tailed) as possible in order to get the accuracy we're after.

I'll be back soon.

HollowPoint

[HollowPoint]

OK;

I'm not going to have time to post pics tomorrow so I thought I'd get it out of the way.

I took some quick pics but the ones of my prototype dies came out all blurry. I'll do those later. For now, here's enough to whet your appetite.

I installed a couple onto the NOE 200 grain spitzer flat base gas checked bullets. Although I haven't added the beveled tail to the bullet yet, you can see what I'm trying to accomplish with these Boat-Tailed Gas-Checks.

These are already some of my most accurate cast bullets out of my K31. I'm hoping that the Boat-Tails will give me better long range performance.

HollowPoint

[slim1836]

Very nice, I look forward to seeing your results on paper.

Slim

[Doc Highwall]

Nice! I would like to see your shooting results also.

[arjacobson]

Great idea but are the checks holding up to the pressures? The reason i am asking is I have had boolits with marks on the base from the sprue. I have recovered boolits with the gas checks still attached and the marks were clearly visible. In fact it looks like the divot in the base of the bullet had the gas check pushed right into it. I am wondering if your BT design will just crush to the flat base of the bullet??

[RoyEllis]

I've gone down this path with the same idea & approach, found gas pressure crushes the check & ruins accuracy unless the boolits base mates to the contour of the ID of the check to support it.
After this discovery & cutting a mold to address the support issue, I found it somewhat difficult to find consistency with the check extrusion, mainly uneven thickness during forming the deep cup and getting wobble from the unbalance. But then my machining & equipment to form wasn't terribly perfect so hopefully yours works through the catches I ran into, it's a capital idea to increase BC of long range cast loads.

As an aside, my attempt was almost a half jacket in length, I cut the mold to eliminate the last drive band and put a crimp groove at it's previous upper edge for the long cup wall to crimp into. I was trying to assure the check would remain attached thru flight.

[HollowPoint]

Great idea but are the checks holding up to the pressures? The reason i am asking is I have had boolits with marks on the base from the sprue. I have recovered boolits with the gas checks still attached and the marks were clearly visible. In fact it looks like the divot in the base of the bullet had the gas check pushed right into it. I am wondering if your BT design will just crush to the flat base of the bullet??

If I were to try to shoot them as they're pictured here I'm certain that the pressure produced by the burning powder would crush the copper checks onto the flat base of these cast bullets.

Perhaps I didn't make it clear enough in my explanation. I was in to much of a hurry to post.

The bullets pictured here are just to give a quick example of what I was attempting to achieve. I still have to machine the additional metal plates that will sit on top of my existing bullet molds.

These metal plates will have the beveled bases milled into them to form the shape of the Boat-Tails on the tail end of my bullets as they are cast.

Once in place, the Boat-Tail- formed on the tail end of my cast bullets will completely fill the inside of the Boat-Tailed Gas Checks and thus keep the pressures of the burning powder from crushing them into whatever odd-ball shape they may otherwise done so.

I'm afraid that's the best written explanation I have right now. You'll have to wait and see what I'm talking about after I get it done.

If I get some time next week I'll start that part of this project and post the results.

HollowPoint

[HighHook]

I look forward to see how this goes. Neat idea. Thanks for the updates...

[n.h.schmidt]

This is really cool. I hope it all works out. I would like to suggest something. Maybe a drop of a epoxy like JB weld put into the BTGC would fill up and support the GC. You use enough so some extra will ooze out when the cup is placed on the boolit with some pressure. Tedious to be sure but may be worth a try.
n.h.schmidt

[XWrench3]

VERY interesting! i will be checking back!

[HDS]

This is the kind of stuff that makes me come to this forum

[HollowPoint]

I was able to get my crimping die done yesterday. That was the easy part.

Now it's on to the "Add-On-Plate" I eluded to in one of my previous replies.

Here are a couple of computer renderings that will give you a better idea what I was
talking about. I hope they make sense to you guys.

Rather than going through the trouble of making a whole new bullet mold from
scratch to accommodate these new style Gas-Checks, I thought this might save me some time.

I'll be setting these parts up on my CAD/CAM software for the next couple of nights
as I get the time. With any luck I'll be able to mill them this coming weekend.

HollowPoint

[btroj]

What is the purpose? Flat base bullets are more accurate at ranges under 200 yards. That is why BR shooters use FB bullets.
The BT doesn't make a real difference until range exceeds 300 yards.

An interesting idea but to what end?

It is well done, that I must say.

[RoyEllis]

What is the purpose? Flat base bullets are more accurate at ranges under 200 yards. That is why BR shooters use FB bullets.
The BT doesn't make a real difference until range exceeds 300 yards.

An interesting idea but to what end?

It is well done, that I must say.

Main point would be to improve BC for long range shots, cuts boolit drop, reduces ranging error misses through flatter trajectory, etc. I've always loved flinging shots waayyyyy out yonder just to see if I could hit targets beyond others self-imposed limits, seeing if I can obtain that last little extra bit. Not particularly useful for hunting and most target competition to be sure, but effort to excel is never a wasted effort, is it?
I tried going down this path awhile back & produced less than satisfactory results, I'll be watching with great interest and hoping Hollowpoint hits a home run with it. I'm certain in my heart it can be done and I'm certain the knowledge will benefit the members here.

[HollowPoint]

"Main point would be to improve BC for long range shots, cuts boolit drop, reduces ranging error misses through flatter trajectory, etc. I've always loved flinging shots waayyyyy out yonder just to see if I could hit targets beyond others self-imposed limits, seeing if I can obtain that last little extra bit. Not particularly useful for hunting and most target competition to be sure, but effort to excel is never a wasted effort, is it?"

Yea; What He Said!

Interesting in it that RoyEllis is the second guy to mentioned that he's also tried this but, with unsatisfactory results. I'd like to know what they believe was the cause of the short-comings in their efforts. It may give me an idea what to look out for as I move forward with this project.

I too think it's a viable idea because not every one shoots or likes to shoot their cast bullets at three-hundred yards or less. At the moment the only thing that might hinder my progress is the fact that I'm working with machinery that isn't as accurate as I'd like it to be. In order to get optimum results from a project like this, It's critically important that everything be aligned and concentric.

If for some reason I don't get the desired results, this (in my opinion) would be the reason for it.

Incidentally; I had a slow day at work yesterday so I got a chance to whittle down some aluminum to the proper dimensions in preparation for the milling process that will give me the Top-Plates that will add the beveled bases that will fill the interior of these new Boat-Tailed Gas-Checks.

If things pan out I might be able to cast a few Boat-Tailed bullets this weekend.

I'll be back.

HollowPoint

[drinks]

I have the Lee 230gr 5r bt mold from Midwayusa, a friend calculated the BC at .450, this has some impressive retained energy and velocity figures, even starting out at reasonable speeds, 1500-2000 fps.
Easy caster, loads good and, so far, has grouped nicely using just wws,ac.

[HollowPoint]

I finished up my scheduled work early today so I loaded my G-Code on the mill and went at it. I had already set up my metal stock yesterday so that saved me some time.

As is usually the case, I was in to much of a darn hurry so after I machined the part I realized that the metal-flap I'd designed into my Boat-Tailed Extension Plate wasn't really needed in order to align it to the top of my bullet mold.

I ended up milling off that metal-flap after the fact.

The good news is that I was able to align my Boat-Tail Extension Plate with the existing cavities in my bullet mold. I made the Boat-Tail shape in the extension plate a hair larger in diameter so that I'd have a small lip in my Gas-Check Shank
for the Gas-Check to crimp to.

It looks like I'll be casting some test bullets this weekend after all.

I have a couple of other 30 caliber molds that I plan on doing the same thing to if this present project pans out for me.

A while back I devised a way to install some nice-fitting Synthetic bullet tips onto my hollow pointed bullets. (rifle and pistol bullets) I figured that the Synthetic tips, along with these Boat-Tailed Gas-Checks would optimize the BC on my hollow pointed hunting bullets; assuming that they're concentric enough so as to not cause the bullets to wobble in flight.

Here's a couple more pics of my progress.

I'll be back after I've cast a few bullets. Then I can officially test fire them.

HollowPoint

[arjacobson]

Gotcha!!! I get what you are trying to do now..Nice work!

[xs11jack]

I am real beginner on this machining stuff. I have a question on the addition to get the boat tail, will the addition add a lot of unwanted weight to the total weight of the boolit? Will the longer boolit change the BC of it? I find this venture fastinating. I am glad someone with the knowledge and equipment is doing this.
Jack

[HollowPoint]

An average traditional copper Gas-Check weighs about 4 grains or so. These Boat-Tailed Gas-Checks are are made from 44 caliber copper Gas-Checks slightly larger than average. I haven't weighed them so I'm guessing they weigh about 5 or 6 grains. Then there's the weight of the additional lead that make up the beveled tail on these bullets.

I'll have to wait till I cast up a few to get the weight of the longer bullets.

I do believe that the added length will add to the sectional density and the BC. I don't know enough about how to calculate exactly how much of a difference it will make.

"I am glad someone with the knowledge and equipment is doing this."

Thanks for the compliment Jack but, I have to admit, reading this kind of gave me a chuckle. When I undertake these types of projects I deliberatly do them as quickly as I'm able otherwise I loose interest in them. I'm not a machinist. I'm just a self-taught no-name goober with with a couple metal working machines and a short attention span.

I have a million project ideas and not enough time in the day to tackle them all. I really hope this project works out like I dreamed it would. I think it has the potential of moving Cast Bullets into the twenty-first century.

HollowPoint