PC bullets with traditional design; holding us back?

[Medicaus]

Hey guys,
first forum post I believe.
I have a question thats been bugging me...
I have heard, and thought myself, that a traditional gas check bullet design, powdercoated with no GC may cause bullets to lead more easily from gas blow-by. Yet there is few bullet molds that don't come with a GC design. I'm wondering if anyone has done empirical testing on mold designs that are flat base, powdercoated and shot it at rifle velocities without issue. It's ok if it hasn't been done, because my next step is to buy a cheap lee mold, mill off the GC area and do it myself. I'm just wondering if anyone has any experience with this before I throw away 50 dollars. If not, happy to give it a go for "The cause" and report back in my 308.

[Freightman]

I took the GC band out of a Lee 200g boolit didn't see any difference up to 2000+ - fps and I don't have a mil or lathe did it with a cheap HF drill press.

[OS OK]

I believe that Dragonheart has done this with pretty good results up to a certain velocity...don't recall exactly where it came up for discussion though...you might PM him and ask?
Look him up in the membership.

[popper]

happy to give it a go for "The cause" and report back in my 308. It's a matter of how much fps/psi you want/need. I've done 1750 for 150gr PB in 308MX, 2100 for 145gr. PB in BO. Give it a try.

[Traffer]

http://castboolits.gunloads.com/show...=1#post3772781
http://castboolits.gunloads.com/show...=1#post3761480
A couple of threads that might interest you.

[Dragonheart]

I would think most into coating would agree we are sucking hind tit when it comes to mold design. We are using molds that were designed to make oversize bullets then cut them down to fit. This is made worse as we are adding several mils of material then having to push more metal around and trying to end up with concentric bullets. Not a bid deal with handguns, but Bama has already shown us all that a PC rifle bullet is capable of excellent accuracy, but only after he basically created a custom bullet. So for me you are correct that we are just making do.

As far as gas checks Charles Darnall of FreeChex fame tells me he sees no need for a gas check with a properly coated bullet as gas cutting is no longer an issue, which is the primary reason for a check. Since Charlie is more knowledgeable about gas checks than anybody I know I bow to knowledge and experience. I do question if there is still some benefit to a properly seated GC as it leaves a flat base, but that could only be proven in a side by side comparison.

Although accuracy was poor at 100 yards I fired a number of 22-250 plain base powder coated rounds in excess of 3500 fps. I did not set up my chronograph, but based on previous load data that is a good number. There was absolutely no leading, just powder fouling, which cleaned up with a couple of passes of a Bore Snake. My intent was to see if the coating had a velocity limit. I would imagine there is one, but not with anything I own.

[popper]

properly coated bullet as gas cutting is no longer an issue

Getting ready to test that in BO - at the same fps, ~ 1900. Using ~ the same alloy I use in 308. So far the 145gr PB is just a tad less accurate than the hornady 150 SPP, 100 fps difference. IMHO the GC is needed for HV rifle. I still have some BHN >36 PB left I might try pushing hard in the 308.

[DHDeal]

Out of curiosity, does the same idea apply to handgun bullets? I'm sure others have created molds for handguns without GGs and I wonder how well they worked. I suspect they work quite well. Looking on Accurate Molds website, I appears some bullet molds are made without GGs.

I'm very tempted to have one made without GGs and see what happens. I would need to measure some of my bullets to get a very good idea of how much my technique for PCing adds to the bullets and account for it. The bullets would be somewhat heavier because of no GGs, but I like heavy for caliber bullets in just about everything I shoot anyway.

I suspect this thread was mainly about rifle bullets, but just thought I would ask about the handgun bullets while I was here.

[Dragonheart]

Gas check are used when the gas pressure is sufficient enough to cause the short duration of the hot gases of ignition to blow past the bullet's seal. This blowby can cause gas cutting and lead to leading of the barrel. In addition it is said the GC provides a scraping action that reduces leading. The gas check also provides a flat base to cover an imperfect base and improve accuracy. Whether you gas check or not traditional lubed lead bullets deposit lead in the barrel.

Powder Coating creates a synthetic jacket and like a jacket eliminates the above problems. Unlike a metal jacket the polymer does not leave copper or other alloy deposits in the barrel. There is no reason I can see to have a gas check on a handgun bullet unless there is a gain in accuracy, which to my knowledge is yet to be proven. Gas checks add to the cost and time spent in the bullet making process. I have a number of handgun molds and none are gas check molds. I personally would not waste my money on GC handgun bullets as I have developed a number of PC loads for my handguns that will group under 1-1/2" at 25 yards; I don't need accuracy beyond that.

[OS OK]

I've read this somewhere but can't find the reference to post it...but, IIRC'ly...a bare lead base under enough pressure and temperature (as in magnum loads) can deposit lead in the barrel ahead of the next round that just irons in into the imperfections or other deposits that were already there.
Tumble PC'ing the rounds totally encases them.
I think imperfect fit to land and groove is also protected from depositing lead even when the PC'd round is gas cutting...the short duration of powder burn temperature doesn't affect the PC, doesn't cut through it.

[popper]

IMO, GG are lube grooves, not GC. Boolits without G.G./L.G. work fine. Many PB boolit designs have rather small rear band - lube in the groove is supposed to add strength to the base - coating doesn't. All of my testing so far indicate that accuracy and HV require the base to NOT be coated, PB or GC. Sag/flow of coating on base doesn't make a uniform base. A previous member demonstrated this by 'uniforming' GC (not exactly flat but uniform in circumference). Group shrunk by 1/2. Brings up a point alluded to by Bama's tool. Given the manuf. tolerances of mould, press, sizer/stems, etc., how 'good' can we install GC, size boolits? If I can keep mine under 2 MOA (yes 1 MOA is better) without flyers, I'm happy. That is acceptable for SD, hunting and range time.

[sparky45]

There are Molds that drop bullets without any lube groves and plain base, at least for pistol.

[castalott]

http://castboolits.gunloads.com/show...-222-Remington

Can't help you with 30 cal but here a custom plain base 222 mold shot at 1975 fps with so so accuracy and zero leading. Coating was HiTek , the boolet had no lube grooves, and the bore was perfect after shooting. You will have to sift thru the article to find that load.

I'm on this same path but can only hobble along...

Dale

[tja6435]

NOE is going to make a boattail no lube groove 30 cal rifle bullet specifically for coating

[castalott]

NOE is going to make a boattail no lube groove 30 cal rifle bullet specifically for coating

Would you tell us more...sounds interesting..

Thanks, Dale

[Adirondack69]

HTC310-168-SP (BT) (1)

Here you go.

[Bzcraig]

I have seen a few no lube groove molds in Accurate's Catalog

[Dragonheart]

The NOE bullet looks interesting and I applaud any efforts in designing bullets for coating, but I am not convinced about the boattail design

First it is well known that a boattail only stabilizes at longer ranges. Second, our main problems with coating is uniformity of the coating, starting with and keeping concentricity, so I don't see this design as an improvement on these issues. From what 'Bama" has demonstrated with 350 yard accuracy, is we need the ability to size or swage a bullet. How do we get a uniform coating on a boattail and how do we size a boattail?

[popper]

I am not convinced about the boattail design I agree but it's only 1/8" long - more like a BB? Only time will tell.

[popper]

Sized some uncoated slick side boolits today, hard alloy AC from 6 or so Mo. ago. Really tough in Lee 308 die. So I started at 310, 309, 308 (actually 3085). Single 'collector' groove 0.160" from base, 0.022 deep x 0.045 wide. Drive bands run 0.45" total length. Width of groove is 0.019 after sizing so filled 50%. After PC, sizing and down the barrel, groove will probably be 'gone'. As we generally oversize by 0.002" all that alloy has to go to the base unless it can collect in a groove. "so what, mine are GCd"? If there is no groove there, the GC could be pushed back - not good. I added a second groove closer to the base on the 170/185 moulds (for 311 30/30 but if I use them in the 308 or BO they go to 310 & 308). Just FYI.