Comparison test of two 30-30 Win loads

While lubed bullets may do well when sized to the throat diameter, the lube smears and flows to where it needs to be. PC is however like a very thin plastic jacket that you don’t want to cut or tear, therefore a smidge over groove diameter seems to be the sizing recommendation.

I’m still in the early experimentation phase with PC, but this is my general understanding of it’s mechanics.

Josh

Bret4207 said:

Any theory on why? Is it related to the ductility or lack thereof of the coating?

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Preserving the coating is important and minimizing deformation helps that. 1 to 2 thousandths over groove usually does the trick. But wait....there's more!! You can get away with lots of loaded neck clearance and even throat clearance caused by near nominal bullet diameters because a) the coating is slippery and b) the coating is tough which allows the bullet to easily slip out of the case, bang around in the throat, and get pushed well into the rifling before pressure has risen enough to deform the base. The smaller the bullet, the easier it engraves, causing even less base damage.

So it's not like a lubed cast bullet. Okay, that will require some different thinking, another set of parameters. Interesting.

Bret4207 said:

So it's not like a lubed cast bullet. Okay, that will require some different thinking, another set of parameters. Interesting.

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You need to put aside everything you know about lubricated cast bullets and start over when you employ powder coat.

Some things are similar, for example the alloy, bullet shape, and powder charge still work together as a system (or very much NOT work well for you, depending on how you choose components and set them up), but the parameters are a lot different for coated bullets. The polymer jacket removes much of the need to fill space with bullet for complete support at launch, but the bullet still needs guidance and support in the right places at the right time to get itself started straight. I have had good results giving the bullet a few thousandths of an inch to "jump" before contacting the throat and choosing a bullet which has a lot of metal where it contacts the ball seat and the origin of the rifling, preferably in the order of nose engraving into the origin of the lands just before the full-diameter of the front bearing surface begins to engage the ball seat. In the dynamic aspect, coated bullets behave a lot more like copper jax and for the same reasons. But...the polymer jacket isn't a tough canister holding the lead core like copper is, so the core is still doing all the supporting and taking all the load. The polymer only really provides an abrasion-resistent surface which can take higher velocity without wearing off on the driving side of the lands, and as mentioned the reduced friction allows the bullet to slip into the safety of the throat much earlier in the pressure curve. While not everyone agrees, I feel that displacement (lube) grooves are necessary for PC bullets to work well. If the alloy has nowhere to go when being squeezed through the throat then the bullet must elongate. Elongation without a tough jacket to keep things together makes for odd movements of the nose and base, just like extruding cake frosting through a piping bag things will curve rather than flow straight. All monoliths need displacement grooves for this reason so the crushing is limited to near the surface of the bullet rather than squishing the entire bullet to its core and drawing the middle toward the ends. If displacement grooves aren't use on rifle bullets at high velocity, excessive jacket fouling of the bore occurs with PC just like copper as Frank Barnes found out with his early copper monolith testing. Minimum deformation during engraving and limiting overall distortion to near the surface (and breaking up that distortion into controlled segments) is the name of the game. Bullets for rifles like to be sized larger than groove dimension by at least a half-thousandth, but no more than half a thousandth less than the throat entrance dimension (assuming the cartridge case fits the chamber closely enough to pilot the bullet into the throat with less than half a thousandth lateral misalignment, otherwise size the bullet smaller so none of the coating gets scraped off on the side of the throat as the bullet exits the case neck). Alloy needs to be sturdy but not nearly so much as with equivalent loads using traditionally lubed bullets. Powder burn speed can be more in-line with what's normal for copper jax at similar speeds and pressures, even faster. No need to use extremely slow powders for (*edit to fix autocorrect putting "PICASA" instead of "PC") powder-costed cast bullets, although it doesn't seen to hurt...except with burn consistency. The PC bullet squirts up the bore and doesn't have the normal engraving resistance of cast or jacketed, so slow-for-cartridge powders have a tough time getting lit well and other tricks. Like I said, it's all different from what you're used to, though there are definite guidelines to follow for best results initially, then the tuning and experimentation is up to you.

PICASA? stupid spell check auto-fill. Every time I use my phone I have to relearn some feature or find and turn off the latest annoying "improvement".

Ian said:

PICASA? stupid spell check auto-fill. Every time I use my phone I have to relearn some feature or find and turn off the latest annoying "improvement".

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I though it was just another acronym I wasn't aware of, or not too smart enough to figure out. Especially considering the topic is powder coating, which I don't do.
I have learned, though, that PC means powder coat, only because political discussions are a definite no-no.

.3085". groove diameter Ok, rocky just making sure. My BO carbine is tight too. 3085 is the largest I can size even turning necks and it works good. I've run hard (~36 BHN) and soft alloy, same mould, PC. Shoots the same. Only Ruger I have is markIII 22lr. My Marlin is the only one I've slugged, tight at both ends but loose in the middle. Pretty normal for cheap 30/30. Still works good.

Anybody with QL that can give a safe load of 3031 185gr RD PC in 336 30/30? Thinking 27gr would give maybe 17-1800 fps with accuracy for 50/50 AC alloy. Not looking for lots of recoil but never used it before. Got some LeverE but it isn't recommended for heavies.

Popper, measure the following: 1. Barrel length from breach face to muzzle. 2. Bullet diameter, length and weight dressed. 3. Weight in grains, of water filled to the mouth of the cartridge cases used, and I will give you the QuickLoad info you asked for.
Rocky

Here is a follow up on the question, "Is there a significant difference between the accuracy of a powder coated, gas checked bullet and the same bullet powder coated without the gas check?

The load: (This is the same for both cartridges except for the presence go a gas check)
NEI 309-173GC PC=Smokes JD Green sized .310" after powder coating.
Range scrap BHN 10. OAL 2.553"
Bullseye 7.2 grains (as suggested by. Ben)
Shots taken @ 100 yards. Temperature 60*F Light gusty wind.





Not all of the group size info is showing on this picture. the size is: .81" X 1.3" Plain Base.
(That would have been a great group without that fifth shot)


It would appear that the plain based powder coated version is more accurate. Is this a significant difference? I am sure the statisticians among us would say that 2 five shot groups is not enough to be significant, and I would agree, but I take this to mean to me that it is not enough difference to make the expense and trouble of applying a gas check worth it.

Rocky

20" 1:10 microgroove 185gr 0.311 dia and 1.00 length. Have some 3031 but never used it and books I have don't go that heavy. Would be used on pigs and paper.
BTW, new scheels store in frisco has some powder (4895, uniqe, h110 type stuff), just shot shell primers and lots of rifles. Not too many pistols but ammo shelves seemed pretty full. Prices a little high.

Good shooting, and thanks for sharing Rockydoc. I have also found good accuracy with checkless PC bullets.

One of the things I have learned is that ductility is more important than hardness. There is balance in #2 alloy that just makes it work well across many calibers and functions so I typically use this as a starting point.

Then I started powder coating and purchasing molds from Accurate. Based upon my own observations and reports from others I started paying closer attention to cast size and quit sizing down so much as to not distort the cast bullets. So as PC would add 1.5~2 thousands to diameter I would order the molds undersized in the traditional sense.

I did have some puzzling results though which I soon could chalk up to different base types of PC material. I would use different materials on the same cast lot, sized and loaded the same and shot from the same rifle at 100 yards over a Magneetospeed. See the chart below of some of the properties of PC as not all materials are alike, this matters as small differences tend to have large variations in outcomes when bullets are pushed hard.

Based upon these tests I now use powders that work in the desired application. As I co-own a custom PC business I have a large library of powders to test from. I use an ES gun for all applications. Interesting observation is the variance of final thickness of the cured coat. Some powders easily go on too thick and cause issues with too fat noses. Record keeping is a must when doing these experiments.

So in closing alloy matters, as cast size matters and PC type and coat thickness matters. The better these different needs are met the better your performance will be.

For example, I shoot cast in the 7.62x40WT using the same charge, 100% case capacity, using a 130gn cast bullet or a 130gn Speer and have almost the same accuracy at 100 yards. This is what is possible when bullet matches the requirements. Small things do matter.

I apologize for this long ramble but am bed-bound in hospital with tubes in me including a catheter so am in discomfort and bored as I’m not working.

Nice post. Yes, it seems that ordering undersized molds is the next step.

Hopefully you will be feeling better soon.

Josh

@BliksemE300 , Ouch, hospital confinement sucks rotten eggs, hope you are on the mend and out soon. Great post by the way.

Joshua said:

Nice post. Yes, it seems that ordering undersized molds is the next step.

Hopefully you will be feeling better soon.

Josh

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Thank you Josh.

Just got back home but am walking like a very old & broken down man.

Back Story:
Last weekend I was at my ranch in west Texas filling feeders, carried 50# sacks of corn easily. Gents take care of your plumbing and don't be shy or scared to visit a professional when things feel off. I almost left it till too late to do something about it.

More rambling:
No range time this weekend but I'll probably do some fiddling in my workshop sitting down. This addiction is what it is.

The matter of proper fit and minimal sizing goes hand in hand in improving accuracy, IMHO. I'm not discounting the knowledge of the old timers but they had to contend with milsurps and other out of spec or worn out parts to make them work right.

Once I became more picky on the barrels etc the next step was to craft bullets that fit just right and are not damaged in any way during sizing and loading. Good case prep and good loading matter more than what people think. The "need" for massive loading output obscures the fact that accurate ammo takes time to craft. I take my time, even though I use progressive presses, to craft each round on it's own. This is done by sending only one round through at a time. I pay attention to each round and inspect it before placing it in the box.

I know I have more satisfaction at the range shooting a limited number of well-aimed shots than Marty McBlammer that empties as many magazines as possible in as short a period of time. He is a good donor of reloading brass though.

The ammo forms a major part of the rifle system and if just one element is out of whack performance can be poor or sub-optimal. Just blindly following the mantra of bigger size, or you can just size the bigger bullet smaller is an economical way in some ways but good outcomes are literally hit-or-miss. I know I'm probably preaching to the choir but it took me too long to get what the old timers such as Glenn and Charles were sharing with us, the ignorant and great unwashed...

Enough ranting, need to take meds...

Ian said:

@BliksemE300 , Ouch, hospital confinement sucks rotten eggs, hope you are on the mend and out soon. Great post by the way.

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Thank you Ian,

The brotherhood on this forum is priceless. This has become my online home from home.

Rockydoc said:

Here is a follow up on the question, "Is there a significant difference between the accuracy of a powder coated, gas checked bullet and the same bullet powder coated without the gas check?

The load: (This is the same for both cartridges except for the presence go a gas check)
NEI 309-173GC PC=Smokes JD Green sized .310" after powder coating.
Range scrap BHN 10. OAL 2.553"
Bullseye 7.2 grains (as suggested by. Ben)
Shots taken @ 100 yards. Temperature 60*F Light gusty wind.

View attachment 17319


View attachment 17320
Not all of the group size info is showing on this picture. the size is: .81" X 1.3" Plain Base.
(That would have been a great group without that fifth shot)


It would appear that the plain based powder coated version is more accurate. Is this a significant difference? I am sure the statisticians among us would say that 2 five shot groups is not enough to be significant, and I would agree, but I take this to mean to me that it is not enough difference to make the expense and trouble of applying a gas check worth it.

Rocky

Click to expand...

It is all to easy to confuse reading one group from each other. Even a rigidly mounted action/barrel combination shoots groups no matter the quality of the ammunition. There are to my mind simply sweet spots. Once you have that it is as good as it will get. At that point additional dispersion is due to the person pulling the trigger. Good as it will get is what I call it.

carried 50# sacks of corn easily Not supposed to eat that stuff
Get well soon. Like my daughter say, God only gave you so many steps, use wisely. Where's the fun in that?