Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
I know I am missing something, but what makes this so different than Lee Collet dies?
I've used various methods to size necks, including standard bushing die setups, and expander mandrels. My original thought for using the mandrels was that their use would likely push inconsistencies in neck wall thickness (I don't turn necks) to the outside, and leave them very straight. FWIW - the carbide mandrels available for neck turning purposes are generally held to much tighter tolerances (actual diameter) than the steel ones. Regardless of the price of the Porter die shown previously, the big advantage there is the precision and range of diameters available; something you cannot easily obtain with neck turning mandrels.
My approach with the mandrels has been to use a bushing die first to size the neck, with a bushing that was either .001" or .002" smaller than that which would give me ~.002" neck tension (interference fit). That way, the mandrel would definitely be opening up all the necks in the 2nd step to some degree, presumably allowing for better final diameter consistency than by using a bushing that sized the neck very close to that which the mandrel would open it back up. For .223 Rem and .308 Win, I used .222" and .306" carbide neck turning mandrels, respectively. I typically use a 0.248" bushing with .223 Rem brass (Lapua) and a 0.336" bushing with .308 Win brass (also Lapua). As the first step, I have sized necks with both 0.246" and 0.247" bushings for the .223 brass, and 0.334" and 0.335" bushings with the .308 brass. If you wish to try this method, the size of the bushing used does make a difference.
The point I wanted to bring out with this post, particularly for those that may not have ever tried using a mandrel before, is that sometimes something that seems like a good idea may or may not necessarily offer an advantage, depending on your particular shooting needs. You have to try it to find out. In my hands for the purpose of F-TR shooting, there was really no advantage to using the mandrel. IMO - the necks were not any better or more uniform than I was already achieving using a standard bushing die with half the effort (i.e. one less step). Your results may vary from mine depending on the type of shooting you do.
The other thing I will point out is that you want to take springback into account if you decide to use this approach, especially if you don't have access to an almost unlimited selection of mandrel sizes like the ones from Porter, which I didn't. My thought had been that using a carbide neck turning mandrel of .002" under bullet diameter would give me about the same neck tension that a bushing already known to provide .002" interference fit would give. This was not so, and springback is the reason. When sizing brass necks down from the outside using a bushing, the springback of the brass opens the necks back up just the slightest bit. In contrast, when opening the neck up with a mandrel as the final sizing step, the direction of the springback is opposite; that is, they close up just a tick. The final result is that although you might think the two approaches would give very similar neck tension (at least on paper), in fact they did not. The neck turning mandrel approach gave me between .0005" and .001" greater neck tension than the bushing die already known to give about .002" interference fit. As a result, bullets were noticeably more resistant to seating with the mandrel-prepped necks. Of course, none of that matters if you have access to whatever diameter mandrel you need, as with the Porter setup. However, anyone wishing to attempt this using commercially available neck turning mandrel, just be aware that due to springback, your neck tension will be noticeably greater than about .002", if that's what you have been using previously with a bushing die approach.
So is the actual number for tension important or just consistency. However miss lead I seem to be I was going down this path due to consistency. Even if you get more tension dont you get more uniform tension with less chance of causing consentricity errors.
I was not trying to correct error, just use good methodologies to prevent causing any. People here got me terrified about that expander ball.You can eliminate the concentricity errors by using good sizing dies on brass shot from a good chamber. Trying to straighten brass at any step in the process is a band aid. Find the point in your steps that concentricity appears and fix it there. If its straight out of the chamber but .003 after sizing then you got die and or brass issues. Fix it there before you move on. The mandrel die isnt for straightening its only for fine tuning neck tension- the last step before seating
The Lee collet die presses the outside of the neck down by by collet to the size of the mandrel, the Porter tool opens the bushing sized neck backb up using mandrels.This doesnt size the neck and is a very precision piece made for the very small percentage of people that varying neck tension affects
I was not trying to correct error, just use good methodologies to prevent causing any. People here got me terrified about that expander ball.
I feel the effort to expand a case with a gauge pin is half what it is with a Sinclair or K&M expander. Maybe its the metal it is made of or because they are hardened and surface ground. MattSo its a really nice piece, but i am trying to understand why one unit would be worth more than another? What will this super cool holder do that the sinclair unit will not? If your running an o-ring below the locking ring to allow for float and alignment, i cant see what the advantage of the more expensive tool is. I love precision tools and if there is a gain in the more expensive tool i would like to know what that is. I hate not making informed decisions.
Would that not be directly related to the grind job you do on the end of the pin? Might be a better transition, or where it occurred in the stroke of the ram?I feel the effort to expand a case with a gauge pin is half what it is with a Sinclair or K&M expander. Maybe its the metal it is made of or because they are hardened and surface ground. Matt
You need to determine empirically what neck tension gives the best results. In my hands, approximately .002" interference fit has almost always worked well. That is not to say that the higher .0025 to .003" neck tension I obtained (via springback) using a neck turning mandrel DIDN'T work. In fact it worked just fine. However, for my intended purpose, the precision and velocity numbers were no better than simply using a bushing die. My thought was why go through the extra step if it's not an advantage?So is the actual number for tension important or just consistency. However miss lead I seem to be I was going down this path due to consistency. Even if you get more tension dont you get more uniform tension with less chance of causing consentricity errors.
No, because the others are tapered. With a press you can feel the difference. MattWould that not be directly related to the grind job you do on the end of the pin? Might be a better transition, or where it occurred in the stroke of the ram?
View attachment 1078629 View attachment 1078630
You can sure get a big collection of sizes easily with porter’s die. I can change my tension 2psi most times