Yes, Mr Ned Ludd, You are getting to my point. I will be shooting 55 Vmax bullets. I have 11,000 of them and I won't be changing. I will be feeding them from an AICS 223 mag so the COAL will be limited. I don't think a long jump is useful. My question is--will the Wylde chamber work with these conditions. There willl be no factory ammo shot in this rifle so I can control any pressure concerns.
Thanks
Ken - as a general statement on setting up a chamber to work with certain bullets, or a range of bullet weights (lengths), one way to think about it is from the viewpoint of optimal bullet seating. From that viewpoint, you have a certain window of optimal seating depth. Let's say as an approximation with the bullet boattail/bearing surface junction of the bullet seated from somewhere just above the donut, or about 1/4 of the way out the neck (above the shoulder), to about 3/4 of the way out the neck or so, which will still usually leave at least one caliber's worth of bullet shank (bearing surface) in the neck. Obviously, these are very coarse approximations, but useful nonetheless, in that they tell you that you have about half the length of the neck to work with in terms of where the bullet boattail/bearing surface junction will be seated optimally at some specific distance relationship to the lands with a given freebore length. In the case of the .223 Rem cartridge, that means you have approximately 0.100" to play with.
I would like to be able to provide you with more specific information, but I really have only worked with two extremes in .223 Rem. One is the rifle I mentioned above that was chambered with zero freebore, and I also own a couple F-TR rifles chambered with 0.169" to 0.220" freebore specifically for loading heavy .224" bullet (i.e. ~90 gr). I have never tried to load bullets in the 50-60 gr weight range, and I don't have a rifle chambered with the similar freebore as the Wylde chamber. In the past, I have tried to use measurements from reamer prints and other means of making the kind of length estimates you are after, but the overall results have not been very satisfying. Sometimes the predictions have been correct, sometimes not. What I have found to be a much more reliable approach is to use the Hornady OAL gauge with the bullet of interest in a rifle which has a
known freebore dimension, and measure CBTO and COAL at "touching". Even though there are some caveats associated with this approach, it is usually good to within a few thousandths, which is fine given that you essentially have about half the neck length to play with as I outlined above.
Using that approach, for example with my zero freebore rifle, it is not too difficult to make a good estimate of how much additional freebore would be required to A) place the boattail/bearing surface junction approximately 1/4 the way out the neck, but not more than 3/4 of the way out the neck. The measurement doesn't have to be exact to 1/1000th of an inch, only close enough that the the bullet boattail/bearing surface junction lies somewhere between 1/4 and 3/4 the way out the neck, preferably close to the middle of the two, when seated at some distance from the lands. The closer the bullet is seated to the middle of the neck, the more room you have for seating depth optimization/adjustment.
There are really only two deal-breakers from this point of view. The first is whether you have to load to mag length. If so, the nose of the bullet of choice cannot be so long that a loaded round exceeds mag length when the boattail/bearing surface lies between 1/4 and 3/4 out the neck. The second is that having a freebore so long that no bullet shank would be left in the neck at all when the bullet is pushed out to touching the lands. In that case, the extra freebore is wasted and unnecessary. Otherwise, you're left with a fair bit of room to play around and still keep the bullet seated within the optimal region of the neck. My suggestion would be to get your hands on some of 55 VMAX bullets, and use something like a Hornady OAL gauge (Stoney Point tool) with the 55s pushed out to touching in a rifle with a known freebore. That will give you specific measurements in terms of CBTO and COAL, as well as the position of the bullet boattail/bearing surface in the neck, and whether rounds loaded that way will feed from your mags. Anything else IMO would be a guess.
The good news is that you can certainly load rounds with the bullet seated much deeper in the neck than would be considered optimal and it won't prevent you from working up a decent load. Obviously, you can't have the bullet seated out so far that no shank is left in the neck, even if it would fit to mag length. Having played around a bit recently with 77 gr .224" bullet loadings, I am surprised at how deep in the case factory 77 gr loads are seated. They are really way down in there, well below the base of the neck. IMO - the geometry of heavier .224" bullets in relation to seating depth and the limitations of mag length are such that there is no way around that. If you want them to feed from a mag, they must be seated that deep in the neck. With bullets in the 55 gr weight class, I just don't know because I haven't worked with them. What I can tell you is that FGMM 77 commercial ammo shoots beautifully in my zero freebore rifle. I can also tell you that the 77 SMKs in that load are seated at about .060" off the lands. Because the meplat of the 77s is very close to the front inside edge of a PMAG, having more freebore to seat 77s out farther in handloads would be useless if I needed them to feed from a mag. Extending the freebore would accomplish nothing but causing the bullets to be jumped even further. For all of these reasons, I am a big believer in taking actual physical measurements. If you don't have a rifle of known freebore, perhaps a friend does that will let you take some measurements with the 55 VMAXs using a Hornady OAL gauge. Once a freebore has been cut, there is no good way to ever shorten it without setting back the barrel. So having the proper measurements in hand is key. The alternative is having your smith cut whatever freebore is necessary with a few dummy rounds in hand. Rather than deciding in advance to go with this specific chamber, or that specific chamber, providing your smith with some dummy rounds that you know will feed properly from a mag might be a better approach. The smith can then extend or not extend the freebore appropriately.
In any event, sorry for the long-winded response. I hope you get everything figured out to your satisfaction.
