20 Vartarg - Case Forming from 223 (Irregularities and Testing)

[mefizto]

Hi Oso,

I know that I wrote that I will abstain from any further discussion until I have build the rounds, so that I have a better practical understanding, but it would be impolite not to respond to your helpfulness.

Regardless of the Neck O.D. (.252" - .254") of either a 221FB case or 223 case (both .224 caliber), the neck on both cases will be reduced (shrunk) in order to form a 20VTG case that fits a .204 diameter bullet... not .224 diameter bullet... this is where/how we arrive at the .231" - .232" O.D. As part of this reduction process the thickness of the neck's case walls increase as we collapse the I.D down from .224 to .204, resulting in either (1) the need to neck turn the 20VTG formed cases or (2) rifle to have an over-sized chamber to accommodate thicker necked cases ("No Turn").

I understand that, and I had already stated that given that I have several hundred Lapua cases, which do have both the thicker case wall and bigger diameter neck, I intend to have an oversized chamber in the neck area. The issue then became - since eventually I will run out of these cases, how to form the cases by myself.

I want to use .223 cases, that are in abundance, wherein the neck is necessarily formed from the thicker portion of the case. Upon forming the differently head-stamped cases, I measured the wall thickness at the neck to be approximately the same as the thickness of the neck of the Lapua case. And here is the first point where L.Sherm and I cannot find common language. My contention is that since the wall thickness is the same, both cases formed by the same .20VT bushing die will have the same outer diameter, but perhaps different wall thickness, since the starting diameter is different, while L.Sherm argues that, cf. post 33 supra:

. . . necked down Lapua 221 fireball will be .231-.232 loaded round. Rem will be about .228 loaded.

This does absolutely no sense to me, hence my statement re building the cases and then continuing the discussion.

Depending upon the cartridge type of the donor case (221, 222, or 223) as well as the specific manufacturer of the case, the dimensions of the donor brass will vary and ultimately affect the dimensions of the 20VTG case. I mention this because you are going to be measuring case necks of 20VTG cases that were already formed from 223 cases. Keep in mind that these measurements will change when you want/need more 20VTG cases, because the donor case will vary even if it is from the same manufacturer.

If this is the case, and I am not doubting you, I am even more confused. The .223 case is standardized, which, BTW, is the other reason that I want to use it, so a reasonable argument could be made that the tolerances must be within what the standard prescribes, otherwise, the cases from different manufacturers would not chamber is certain rifles. So, what an I missing?

Despite all the best planning, there is a good chance that you will need to do some neck turning to feed this rifle... just keep that in the back of your mind.

Either that, or I just discontinue forming the cases from that particular head-stamp if the first few samples indicate such a need.

What I have learned in my brief time in wildcat is "Don't Recreate the Wheel".... someone else has already tried or thought about whatever you're questioning/exploring. Unfortunately, most of these experienced hands in wildcatting are older and less likely to have felt the need to do a write-up and spontaneously post their experiments and findings on the internet. You just need to ask the question and wait to get the response from those who have the knowledge...

Well, the problem, as I see it, is that when I was searching, I found several contradictory statements, thus as a "pre-novice" how do I decide what is and/or is the correct answer?

To wit, and this is by no means dig at L.Sherm, as I truly appreciate his help, look at this very thread, in response to his assertion that the dimension at the .200 line is 0.27XX, cf. posts 31, 33, I posted the dimensions of the case wherein the alleged dimension is nowhere to be found.

Its hard to be patient when you are focused and excited on a project that you can wait to start using.

Indeed. I cannot specify the reamer until I understand, or have the false impression that I understand, what to do regarding the cases.

Side Note: Sherm helped me build a couple of wildcats, including converting a vintage Sako into a 20VTG. I was hoping he would join in on this thread to lend his knowledge and practical experience building rifles. He was extremely patient and kind with me when I was trying to figure everything out for the first time.

Indeed, he and I had communicated previously via p.m., and it is entirely possible that the misunderstanding stems from my inability to correctly express myself.

Kindest regards,

M

 

[Oso]

Ok - I think I am getting a better understanding of where you are struggling. You have a current batch of Lapua 221 Fireball brass that you plan to use now to form and shoot 20VTG, but at some future point you realize that you will be forced to make additional 20VTG cases from 223 brass. The challenge "Million Dollar Question" is what neck diameter should you get your rifle chambered so that it will be appropriate sized for the future cases. Honestly, .232 vs .234 or .235 are very small differences. We all strive to work the brass only as much as needed, but unless this is a competition benchrest gun these minor differences won't be noticeable in performance. The typical factory rifle has a chamber with much more neck clearance.

You are correct is that when you form 20VTG from 223 (regardless of headstamp) will have the same external dimensions if formed through the same dies. As you noted the main difference will be the wall thickness, which translates into the I.D. of the neck on the newly-formed 20VTG case. After forming the 20VTG cases (reducing dimensions) , one of the last steps is to then run the cases through a neck expander mandrel in order to open up the neck I.D. to the proper dimension (bullet diameter less amount of neck tension that you desire). After this step the neck O.D. has now increased.... and may be different between cases formed from different donor brass (headstamp &/or production year). Once the bullet is seated in the neck the final loaded neck OD may be too large (insufficient clearance. This is point at which neck turning may be required to thin the neck wall thickness for proper clearance, which is what you are trying to avoid by selecting a chamber neck diameter that will fit the future donor brass. If you want an exact answer then get rid of a variable.... Today, go buy 1,000 - 2,000 cases to serve as the future donor brass and set them aside until you need to use them. Case form a small sample set (10-20) using your 20VTG dies, trim to length, expand the necks, and then load them as dummy rounds and take measurements. This is going to give you the definitive answer. Order your reamer based on the sample loaded neck diameter plus .002" of clearance. This takes out all the uncertainty and guesswork.... you just have to be willing to buy a sufficient quantity of cases to dedicate for future use. This isn't a big deal...ask me how much brass I have squirreled away for dedicated projects/rifles. Welcome to a Higher-class of Hoarding!!!

Any 222/223 brass case can be used, but not all brass cases are manufactured to the same level. Due to their consistency of manufacturing and durability, I will either be using Lake City brass or Lapua brass. There is no reason for me to make do with a less desirable case. I would rather do some neck turning to make perfect cases then selecting/using sub-optimal cases for the simple convenience of avoiding neck turning. Fiocchii (GFL) brass is not worth using.

Todd Kinder's reamer design for 20VTG has a .232 neck.

 

[mefizto]

Hi Oso,

Ok - I think I am getting a better understanding of where you are struggling. You have a current batch of Lapua 221 Fireball brass that you plan to use now to form and shoot 20VTG, but at some future point you realize that you will be forced to make additional 20VTG cases from 223 brass. The challenge "Million Dollar Question" is what neck diameter should you get your rifle chambered so that it will be appropriate sized for the future cases.

Exactly; I would just add that I would prefer not to turn the necks at all, or, at worst, turn the necks for as few cases as possible.

You are correct is that when you form 20VTG from 223 (regardless of headstamp) will have the same external dimensions if formed through the same dies. As you noted the main difference will be the wall thickness, which translates into the I.D. of the neck on the newly-formed 20VTG case. After forming the 20VTG cases (reducing dimensions) , one of the last steps is to then run the cases through a neck expander mandrel in order to open up the neck I.D. to the proper dimension (bullet diameter less amount of neck tension that you desire). After this step the neck O.D. has now increased.... and may be different between cases formed from different donor brass (headstamp &/or production year). Once the bullet is seated in the neck the final loaded neck OD may be too large (insufficient clearance. This is point at which neck turning may be required to thin the neck wall thickness for proper clearance, which is what you are trying to avoid by selecting a chamber neck diameter that will fit the future donor brass. If you want an exact answer then get rid of a variable....

Yes, you are correctly restating my in-artfull blabbering. And because the bushing die forms the case in two separate steps: (i) decreasing the outer diameter, and (ii) expanding the inner diameter to the correct dimension for the elected bullet tension, the wall thickness will determine the final products' outer diameter. That is, why I have been searching for a collet die, which performs the (i) and (ii) in one step. The case may need final trimming, or, alternatively, trim it beforehand to a length accounting for the growth using the collet die.

In that regards, what about, instead of turning neck, ream the inside diameter? The reason for asking is that a friend built a fixture that aligns the case with a drill press/milling machine.

Today, go buy 1,000 - 2,000 cases to serve as the future donor brass and set them aside until you need to use them. Case form a small sample set (10-20) using your 20VTG dies, trim to length, expand the necks, and then load them as dummy rounds and take measurements. This is going to give you the definitive answer. Order your reamer based on the sample loaded neck diameter plus .002" of clearance. This takes out all the uncertainty and guesswork.... you just have to be willing to buy a sufficient quantity of cases to dedicate for future use.

That is exactly what I am doing on the different manufacturers' brass that I had acquired.

Due to their consistency of manufacturing and durability, I will either be using Lake City brass or Lapua brass. There is no reason for me to make do with a less desirable case. I would rather do some neck turning to make perfect cases then selecting/using sub-optimal cases for the simple convenience of avoiding neck turning. Fiocchii (GFL) brass is not worth using.

This may be, what I may evantually end doing. However, given the manner in which the supply chain is going, I wonder is one will have a choice in the future.

Thank you very much for the education.

Kindest regards,

M

 

[Oso]

Now we are making progress.

As far as supply - unfortunately, right not is worst time to be starting something new and also being in a rush. Whatever supply of brass you purchase, you want to buy a sufficient quantity and make certain they are all from the same lot to ensure all cases have the same dimensions. At the moment and for the foreseeable future (1-2 years) this is going to be challenging and expensive. Honestly, the money you'll save by buying neck turning tools and the added flexibility to use any brass you find will cost far less than the premium price you'll be paying in todays market to buy 1k-2k of quality brass compared to the pricing pre-panic/shortage. Just something to think about...

I am not as familiar with the collet dies so I don't know if it is going to get both jobs, expand neck and compress neck walls to uniformity, done as well and consistently as you are hoping. I would do a Search on the Forum on "Collet Dies" and see what threads have been written from other people's experiences. This may save you from any uncertainty and help direct your pathway forward.

Neck Reaming - the consensus is that neck reaming is not a good option. From what I have read and discussed with others, the reamer has a tendency to leave an uneven, rough finish inside the neck, which is the last place that you want anything other than smooth. You could try to remediate this by then using the collet die or an expander mandrel to iron/smooth out the inner neck surface. Ultimately, you will be pushing these irregularities to the outside of the neck perhaps starting a cycle of "Ping Pong" with each firing. You'll have to experiment to see if this makes any difference. Again, do a Search on the Forum on "Neck Reaming" and see if someone already has tested and what the collective knowledge is for the process.

Last thing worth mentioning is Annealing. You will want to anneal the newly-formed 20VTG cases. This will make the necks softer reducing the chance of splitting. This is beneficial not just for case forming but also just the day-to-day wear and hardening from expansion during firing and reduction during resizing. There are any number of ways to do this from DIY propane annealers or heat coil induction annealers. Something to start exploring if you don't already have a path/process in place. I recommend doing a search on YouTube for "Case Annealing"

Good Luck!

 

[232]

New LC 223 brass formed to 20 vt will have a .235 nominal neck dia with a bullet seated when not turned or reamed. This is from experience, not from the "collective".

 

[mefizto]

Hi Oso,

thank you for the reply.

Yes, it is not the best time. A friend and I were able to collect literally bags of .223 in the desert, left there from times when people did not care. I have learnt a lot by Processing the tarnished brass; that is, what I am using for my experiments.

I actually used a collet die on a different cartridge, so I know how it works. However, it is not available for .20VT, but I have an idea, so I will ask my friend to built something.

Thank yo for the notes re neck reaming.

Re annealing, yes, I understand that I will eventually need to do so. One problem is that the tools are not exactly cheap, and their purchase cannot quite be spread over time.

Hi 232,

thank you for the reference point. It seems that as much as I hate the idea, neck turning is in my future.

Kindest regards,

M

 

[ricco1949]

New LC 223 brass formed to 20 vt will have a .235 nominal neck dia with a bullet seated when not turned or reamed. This is from experience, not from the "collective".

I can confirm that LC brass forms to a .234-.235 VT loaded round......I've made thousands of them. I had Dave Manson grind a .238 neck reamer to use after my .232 chamber reamer so I could try the brass without turning it but I haven't used it yet.

 

[mefizto]

Hi rico1949,

thank you. So you had decided to re-bore the chamber in lieu of neck turning.

Kindest regards,

M