Powder Coating and Lube Grooves

[dddddmorgan]

I'll apologize if this has been covered but as I've stated many times, I am terrible at searching a subject on forums.

I'm going to begin powder coating some of my cast boolits and I'm wondering if there is a correlation between pressure and lube grooves on a cast/coated boolit?

Here's what I mean; If you have a cast boolit with lube grooves that obviously reduces the bearing surface of the boolit, but if you like the powder coating and it works well can you just get a mold with no grooves (I'm thinking easier to cast) and still have the same pressure?

Hope this makes sense.

[GregLaROCHE]

Lots of people are starting to buy plain sided boolit molds. I got one several months ago, but still haven’t had a chance to try it out. I got mine from MP moulds. Good quality at a very reasonable price. Shipping is super fast if what you want is in stock.
https://www.mp-molds.com/

[jessdigs]

No lube grove molds release bullets a lot easier, but they can only be used for pc and you limit your resale audience. I have several of them from mp and really like them.


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[nhyrum]

I think what's more important than just bearing surface area, is bearing surface overall length, and whether or not there's a groove somewhere in the middle, it doesn't matter.

But yes, people do make no lube grove molds specifically for coated bullets, but lube grove bullets coat just fine too. The no groove bullets are a few grains heavier

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[405grain]

There's some debate about the utility of lube grooves on PC boolits. The issue is that as the boolit engraves in the rifling the displaced material needs some place to go. With the lube grooves the displaced material smooshes down into the lube grooves. Without lube grooves the displaced material might get forced back to the base of the boolit. Any deformation of the base effects accuracy negatively. If this is the case, a smooth sided PC boolit might not be as accurate as one with lube grooves. To sort this out someone who has similar molds: one smooth sided and the other traditional, needs to do a side by side comparison. In example, shoot four 5 shot groups with each type boolit, from the same gun, at the same distance, and see if there's any difference in grouping. Without evidence this argument is just theoretical. (I'd try it, but I don't own any smooth sided molds.)

[oley55]

There's some debate about the utility of lube grooves on PC boolits. The issue is that as the boolit engraves in the rifling the displaced material needs some place to go. With the lube grooves the displaced material smooshes down into the lube grooves. Without lube grooves the displaced material might get forced back to the base of the boolit. Any deformation of the base effects accuracy negatively. If this is the case, a smooth sided PC boolit might not be as accurate as one with lube grooves. To sort this out someone who has similar molds: one smooth sided and the other traditional, needs to do a side by side comparison. In example, shoot four 5 shot groups with each type boolit, from the same gun, at the same distance, and see if there's any difference in grouping. Without evidence this argument is just theoretical. (I'd try it, but I don't own any smooth sided molds.)

This and to some degree the same can be said when YOU size your bullets. In my limited experience the smooth sided no lube groove bullets require a good bit more muscle during the sizing process, and that's with 50/50 alloy. I expect a smooth sided boolit in a hard alloy would build up some serious muscle mass.

[cainttype]

If you’re curious, test it.
There is never anything wrong with firsthand experience, but you will quite often find “general knowledge” offered on forums, in magazines, LGSs, etc. to be wrong. Things that “sound good” can/will be repeated as common knowledge, but you might find the truth to be different.
You’d probably want a chronograph and a good benchrest to test both velocity and accuracy… Keep accurate, detailed reports on your results and report back…
I’m sure you’d find a good number of people interested in the results of a well-done comparison.

[dddddmorgan]

If you’re curious, test it.
There is never anything wrong with firsthand experience, but you will quite often find “general knowledge” offered on forums, in magazines, LGSs, etc. to be wrong. Things that “sound good” can/will be repeated as common knowledge, but you might find the truth to be different.
You’d probably want a chronograph and a good benchrest to test both velocity and accuracy… Keep accurate, detailed reports on your results and report back…
I’m sure you’d find a good number of people interested in the results of a well-done comparison.

Point well made. I'm with 405grain, as I have only one type of mold.

We'll see what the future holds. Perhaps the opportunity to do some testing will present itself. I have a chronograph and a bench and a nice range I can use with even nicer benches.

[Forrest r]

FWIW:

Several years ago I bought a used lee 6-cavity mold on this website, tl 356-124 tc, to do a little testing with. I left 2 cavities plain, cut the bb base and all the lube grooves out of 2 cavities and cut the bb base out and all the lube grooves except the top lube groove in the last 2 cavities. I left the top lube groove to use as a crimp groove for testing in the revolvers.

Cast the bullets with the typical 8/9bhn alloy (range scrap) that I use for 90%+ of my bullet casting needs. Used my favorite john deere green pc and sized everything to the typical .358" that I use for all my 9mm/38spl/357mag.

Did head to head testing with all 3 different designs in several different firearms chambered in 9mm (3), 38spl (2), 357 (4) and several different powders.

At the end of the day I couldn't say 1 way or the other if the solid bodied bullet was any more accurate then the original design or the bullet with the top lube groove. More likely then not that bullet is simply a poor design.

I only have 1 mold that doesn't have lube grooves in it. I use/shoot a lot of those bullets in the 38spl's & 9mm's. I have swaged my own lead bullets for decades, this is where most of my non-lube grooved bullet experience comes from.

With a strait walled non grooved bullets the bullet base has to be square to the sides of the bullet or accuracy will suffer. I never likes sizing traditional bullets over 3/1000th's in 1 pass for this reason, possible bullet deformation. I believe this is where the traditionally designed lube grooved bullet has an advantage of the non lubed grooved versions of the cast bullets. Namely the ability of the lube grooved bullets to be more forgiving and true it's base to the bore when under pressure.

[Petander]

I coat both NLG and trad grooved bullets. Hi Tek & PC.

Comparing is difficult because after removing grooves, it's not the same bullet any more. Weight , sectional density and center of gravity will be different. The whole ballistic ballpark.

But I like NLG:s, haven't seen any accuracy issues. I keep buying mostly NLG molds now, whenever possible.

I load groove-less at least 9mm, 357, 45 ACP, 45-70 and 500 S&W. Got one for 470 NE ordered from Accurate. My coatings are holding good with NLG:s.

It's good to have options.

[Daekar]

I have 4 molds, 3 of which are NLG. I can't tell any meaningful accuracy difference between the the regular and NLG. The most accurate one, for me, is the heaviest NLG, but the Lee 358-158RF is perfectly acceptable when loaded to reasonable velocities.

I prefer NLGs, but I wouldn't agonize over it as long as your traditional mold has decent bearing surface.