So I’ve been away for some time now and come back to find the (cast bullet) world has turned flat (no lube groove). For years I’ve loaded 45acp with 200 grain swc and 9mm with 124grn rnl with stellar results at 25 and 50 yards. These are coated, lube groove Bullets, btw.
I went to restock my projectiles the other day and see that many suppliers have gone to a flat sided mold.

My question is, has anyone noticed accuracy differences going from a lube groove bullet to a flat sided bullet?

Thanks in advance.

I don't use coated cast bullets, only conventionally lubed ones. A lube groove and lube is necessary on a conventionally lubed bullet. Seems a groove would serve no purpose on a coated bullet. Of course, regardless of how a cast bullet is lubed (assuming the coating serves as a lube) bullet diameter would still have to be correct for the cartridge, chamber, and bore.

Coated bullets do not require lube and it is a little easier to cast bullets without the lube groove. If you are shopping for traditional, non-coated cast lead bullets, they will have the lube groove.

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I can't tell the difference. Since there's no traditional lube, there's no need for a groove. In theory, the increased surface area of the driving bands should increase accuracy.

I'm sure from a production standpoint they run better. But like I said, I can't tell the difference but I haven't tried bench-resting.

I’ve approached this brave new world in this manner…

The lube groove bullets (when powder coated, no lube in these grooves) are a design that goes back twice the number of decades that I do and they work. Traditionally known excellent loads for these bullets exist, so I am perfectly happy using them.

The newer age no lube groove bullets may work just as well — I suppose it’s possible that they even work better, but one this is certain, they are NOT the same, and why this matters is that you’ll need to play with either your powder charge or your COAL (or both) because your internal combustion space is likely different and the profile of your loaded round is likely different, and you’ll be re-inventing the wheel with them.

Is that a horrendous task?! Not really. But again, I’ve had plenty of fantastic performance from the familiar bullet and dinking around with a new one isn’t my first choice when I have options.

Most recently I had to make this choice with powder coated 9mm slugs. And 9mm is a high pressure round with an exceptionally small combustion space so the COAL’s affect on pressure can be quite large.

I'm not a competitive rifle shooter, but few, if any, of the cast bullet rifle match shooters use coated bullets. Apparently, coated bullets haven't advanced to the point where they have an accuracy edge over conventionally lubed cast bullets with lube grooves. That's a general statement I make based solely on published match results.

However, in response to your question regarding accuracy in handgun cartridges (and the same should apply to rifle cartridges as well), there should be no discernible accuracy difference because of a lube groove or lack thereof with a coated bullet, IF that is the only difference. It's important to note there could be other changeable factors and bullet diameter is only one of them. Any change can alter results.

Thanks for the replys!

It’s my understanding that the non-groove (flat sided) Bullets will have a slightly shorter oal due to the extra lead required to fill in the groove, this allowing for the same original weight. One vendor that I spoke with mentioned that his grooved molds finally gave out and he just purchased the flat sided molds since that was the trend.
And, judging by what’s out there it looks as though many have done the same but to what end.

As mentioned above, I really don’t want to reinvent the wheel as these loads and Bullets have been my go-too for many years. Time being limited and all I was hoping to side step another development process on two common cartridges.

I powder coat exclusively. I always thought the bullet with a lube groove was a proven bullet. I love my RCBS KT 150, accurrate beyond my abilities. That said, how does one account for plated or jacket bullets with no lube groove? Would it not be close to the same thing? I realize there is a difference in material and the lead bullet will be slightly larger but the shape will be the same with the same bullet to barrel contact.

I have not seen any difference in accuracy between coated bullets with and without a lube groove. The only thing I see is, it just looks cleaner when loading, not that anyone but me can see the lube groove after reloading.

IMO you can buy coated bullets without a lube groove without worries. The only ones I have used are by the Missouri Bullet Co.

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Freedom is never free!!
SWCA #3437

Thanks for your reply.
Did you have to adjust your load at all between the two?


On a side note.
Your quote has great meaning to me, especially now, having lost an uncle and brother in the fight for this countries freedom those words mean more now than ever given what’s happening in Europe.

The no groove bullets are more forgiving to seat as they will try to straighten out where as a grooved one can go crooked and shave more easily.

Please explain. I've never seen any indication of such, but I may have missed something.

Never saw this and I've loaded many 10's of thousands of lube grooved pistol bullets. If you bell the case a few thousands like you are supposed to it won't happen.

Certain bullets, if I set them cockeyed, will shave. With no groove they'll straighten up for me. I'm sure it's just my setup but it can be the difference between 1-3 per hundred shaving and none.

Bell your cases a little more then. I think I'm about 10 thousandths. Mine are not always perfectly lined up and they straighten out immediately as I seat them with no shaving.

Regardless of bullet type, if you use a flat-faced seating stem/punch with anything except RN the flat punch and flat bullet nose together assure the bullet will be seated straight.

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Gunsmithing since 1961

No Sir, I did not have to change the load but of course I did drop back and work back up just to be sure like when you change any component in a load.

I'm sorry for your loss and I'm grateful for your family's service.

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Freedom is never free!!
SWCA #3437