Thanks much. [img]images/icons/smile.gif[/img] It's been cold here for the last three weeks or there abouts, below zero or in the single digits, not much fun. No bare ground like last year either. The warm winds will come and be sure to melt it all off soon, that much is a given. Snow just doesn't stay long here in this valley like it does elsewhere, iceland is a good way to describe it. [img]images/icons/grin.gif[/img] Farmers almanac calls for heavy snowfalls this year so we'll see.
Any conclusions on the polymer tips, if they're worth using or not? Where do you buy those at seperately? I wonder how they'd work in the X bullet for LR work.
Thanks Steve Shelp,The pics of Dave's cutter are a big help...At least i know what/how is being done on the other side of the world...I have nearly finished the point up die as per Henry Childs set up and will test as soon as it rains...Where could i purchase the plasttic tips like the ones in your pic ..JR..Jeff Rogers
Brent & Jeff,
Those tips were supplied by a bullet company that I'm not sure I'm at liberty to say at the present. Like I've mentioned before this has been an ongoing experiement over a period of time and data is continually being fed back to "the source". I'm not playing oppossum with you, but I was asked to keep quite.... so I must honor that request at the expense of not being able to tell ya'll the whole story. If I was given the go ahead to say who, what, when, where, why, and how.... I'm pretty sure even I couldn't buy them myself at this time.
Now about the tips and how they work.... obviously it makes your BC go up and keeps the BC uniformand that's a good thing. That tip on a 300gr MK is an awesome looking bullet. I gained about a 12-16" of elevation at 1000yds using them. This is the reason for cutting the meplat to begin with... was to prove or disprove if uniform meplats make a difference. The end result was to eventually install plastic tips. The cutting of the meplats was merely a cheap easy test to the end means of uniform plastic tips.
The cutter allows you to uniform already existing bullets (loaded or unloaded) and enjoy the benefits of meplat uniformity without going all out to install the tips. The last batch I made up at Dave's shop was 86 bullets and it took well over an hour. Eventually my thrist for a beer overcame my desire for more plastic tipped bullets and the lathe was shutdown for the night. [img]images/icons/grin.gif[/img]
The true test I beleive now lies with the USAMU testing the Dave L. mentioned above. They have the means to truely test, with some statistical certainty the thousands of rounds over different ranges and to get some true repeatable hard numbers. I don't think anyone in our little group has/had any grand allusions of our tests standing up to hard scientific scruntiny. I think we were trying to show that, "hey there's something here and here's rough data".... will someone pick up the ball and make it happen. In that sense the testing to date has been a success and the wheels are definetly turning in more places than NC on this subject.
You couldn't do much better than to have Henry as a reference. I've shot at many matches with him and he usually sets up next to Dave and I. Henry is a walking calculator/encylopedia of internal and external ballistics/mathematics. Henry even shot aluminum tipped bullets at one time that he made himself. That was an interesting experiement with some drawbacks that were encountered.
Steve ,Infos been great,looks like i might have to make some tips to try out,reckon i know the right plastic to use it machines up nice.Brent ,i don't get cabin fever with the heaters and overcoats , At this time of year i get, Hide in the airconditioner type fever...It's warming up now, be bloody hot soon today's not bad it's 92deg F because of the low cloud cover, back to over a 100 in a coupla days..JR..Jeff Rogers
a question for the knowelagable people on this board from a newbie, since the vertical stringing question is addressed here. I always woundered how much effect extreme spread had on vertical stringing. I look at hornady balistic manual and 100 fps at long range seems to have a great impact on vertical shot to shot. I know this is extreme considering most calibers being used but 25 fps from my M1A @ 600 is relistic for me. Is it theory or reality? thanks
That's too funny! [img]images/icons/grin.gif[/img]
I take the cold "much" better than the heat, getting out shooting is much easier when it's warmer than it is now tho. At least it isn't -20 to -40 deg F or colder, that I'm thankfull for.
I think you're asking if it does have an effect with lower extreme spreads? If so, the answer is absolutely. If BC, wind, BP and every other variable, including the rifle capable of bughole groups, the slower shot will always be lower than the faster shot, 5, 10, 15 fps or whatever, time of flight will be different and so will trajectory.
A ballistic program is the easiest way to see what effect a shot with a different MV will produce in vertical error.
This is one of the important goals in load development, not just tiny groups. 10-15 fps MV ES is what I shoot for, although some loads I have refuse to go below a solid 20-25 fps ES. Knowing the probable grouping limitation of the load is important, what ever ES you use. If the ES says vertical could be 16" at 1000 yards, and you shoot many groups with the load that go under 10", be prepared for the eventual 16" group or larger because it will happen and you can't count on the 10" groups.
POI shifts between trips to the range or field:
A more temp stable powders will also help you reduce large vertical errors from mild temp swings, very much a positive step that should be taken when shooting LR. ES should be noted at different temps for the load too, it may be quite different at one extreme or the other.
A swing in BP will also shift POI considerably at LR. Ballistic programs are usefull to understand what to expect ahead of time here too. Using the exact BP and MV on the drop chart will help in big ways at LR. This is where a ballistic program on PDA, along with a wind meter/ weather meter can give you an edge by using real time data.
Once you have established your known drops at a known BP, temp, MV and BC, matching these come ups in the ballistic program, and then modifying them with it makes things pretty simple and accurate in the field.
How close do you want POI to be to POA in the field? Well, the closer you know you can keep them to each other, and the smaller you know you can keep it grouping, these will largely determine your accurate effective range.