Any Benefit to No Lube Groves For a PC Bullet?

[Hanzy4200]

I want to start using a lighter weight 9MM bullet, after experiencing some issues with the Lyman 147 gr mold. Keep getting random bulge rings no matter what I do. Toyed with crimp, select brass sorting, ect. Decided to put it on the back burner and focus on a new design for a bit. So...…

I am eyeing the options from Accurate, as well as the typical lineup. The plain un grooved designs look very aesthetically pleasing. As I am PC'ing more and more, having the groove isn't critical. My main question is if there is any benefit to using these smooth sided designs over the traditional lube grooved, if used with PC.

[tomme boy]

Cast easier with no grove.

[JonB_in_Glencoe]

Some think the groove provides a place for metal to be displaced to, when the boolit is squeezed through the rifling. If the boolit has no grooves, the displaced metal is likely forced to the bottom (or maybe the top?), which could make a distorted base, possibly effecting accuracy.

I know many others have used them successfully, and they will likely chime in right after me. Also, for most all pistol shooting, the little bit of lost accuracy from the condition I mention, is probably not even measurable.

[John McCorkle]

More surface/bearing surface in contact with the rifling.... haven't done testing but I can't imagine more contact with rifling being bad for accuracy...

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[jessdigs]

The NLG bullets jump out of my mp brass HP molds without tapping or fighting it. You open the mold and they fall free. I love loading pc'd NLG HP bullets.

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[bmortell]

i always recommend half way in between. i just get a few of the small tumble lube groves for displacement, which is easy to get added from him. then it still drops easy but is more multi purpose.
i get a size in which i could just tumble lube from the mold and shoot unsized if i wanted or was lazy. or normally id PC and then size with it

[KYCaster]

Some think the groove provides a place for metal to be displaced to, when the boolit is squeezed through the rifling. If the boolit has no grooves, the displaced metal is likely forced to the bottom (or maybe the top?), which could make a distorted base, possibly effecting accuracy.

I know many others have used them successfully, and they will likely chime in right after me. Also, for most all pistol shooting, the little bit of lost accuracy from the condition I mention, is probably not even measurable.

Yeah, what he said ^^^ !
Why does Barnes put grooves in their solid copper bullets?

YMMV
Jerry

[NyFirefighter357]

More surface area could also cause more friction. I like the idea of some lube grooves even if not as deep. As I understand with PC you can shoot a softer bullet and also let the bullet swage down the barrel without sizing, well I guess with in reason. The groove allows for this displacement.

[Winger Ed.]

Why does Barnes put grooves in their solid copper bullets?

Lead is soft enough that the added friction of no grooves is almost too small to matter.
Especially with cast that operate so far below maximum pressures.
If the solid one is slower than a grooved one, no big deal.
You can pump it up to compensate and still be well inside a safe pressure range.

That series of Barnes bullets advertises them as being faster.
They may have found that reducing the bearing area (and friction) on a solid copper bullet, but it still seals the bore,
it can get faster speeds for the same pressure as a 'slick' one of the same weight.

[44Blam]

I PC my boolits so I tend to order my molds without the lube grove. I see no reason for lube groves if you coat the boolit with PC or HiTek.

[kevin c]

It seems that others' experience is different from mine, but I have a 147 lube grooved bevel base design that, compared to the same weight grooveless BB design, takes significantly less powder to make the same velocity out of the same pistol. Both designs are made from the same alloy, coated the same way, sized through the same die, loaded with the same lot of the same lot of powder, same brass and primers, and loaded to the same internal volume for the powder. I suppose you could argue that the interference fit is different, but I believe it's the difference in bearing surface.

[tomme boy]

Copper weighs less than lead. So a bullet of the same weight made out of copper will be about 1/3 more longer. This can and will increase the bearing surface and pressures will spike. So to combat this the copper bullets will have grooves cut into them like a lube grove to reduce the bearing surface to help reduce the pressure the bullet can make.

an example I ran into was 8mm Mauser. I had a bunch of bad Romanian 8mm. It was 154gr fmjbt steel core bullets. I loaded these to a mild 150gr load that has alway shot good for me in the past. It blew the primers out of the case. Come to find out the bullet was the same length as a 200gr bullet because of the steel core. I loaded it with 200gr data and it was fine. It then repeated the same velocity of the original loadings. So the bullet acted as if it was a 200gr but was actually 154gr. Same thing as the copper bullets ran into when they were first being developed.

[popper]

Friction is NOT dependent on surface area, just radial pressure. But coeff. of friction changes with TEMP. More material has to be moved into the grooves. That takes energy (pressure). No groove means more surface for the grooves to catch without over stressing the bullet material.

[Lloyd Smale]

Yeah, what he said ^^^ !
Why does Barnes put grooves in their solid copper bullets?

YMMV
Jerry

i was told barnes did that so there was less bearing surface=less friction=less pressure.

[JimB..]

For heavies, having no lube groove makes for a shorter bullet which can be easier to stabilize.

[mrbigsteel]

Would bullets with no groove release from molds more easily?

[dverna]

Would bullets with no groove release from molds more easily?

Yes....

[Conditor22]

Some think the groove provides a place for metal to be displaced to, when the boolit is squeezed through the rifling. If the boolit has no grooves, the displaced metal is likely forced to the bottom (or maybe the top?), which could make a distorted base, possibly effecting accuracy.

I know many others have used them successfully, and they will likely chime in right after me. Also, for most all pistol shooting, the little bit of lost accuracy from the condition I mention, is probably not even measurable.

A little polishing (leementing) and you can get boolits to fall out of most molds with the right rhythm for that mold

I also agree with JonB

I can get 1 hole groups with PC'd boolits that have lube groves, why buy a mold that loses its versatility.

IF you ever decide to sell that mold, you limit the number of people that can use it.

My 2¢

[Burnt Fingers]

I want to start using a lighter weight 9MM bullet, after experiencing some issues with the Lyman 147 gr mold. Keep getting random bulge rings no matter what I do. Toyed with crimp, select brass sorting, ect. Decided to put it on the back burner and focus on a new design for a bit. So...…

I am eyeing the options from Accurate, as well as the typical lineup. The plain un grooved designs look very aesthetically pleasing. As I am PC'ing more and more, having the groove isn't critical. My main question is if there is any benefit to using these smooth sided designs over the traditional lube grooved, if used with PC.

https://www.uniquetek.com/product/T1736

This powder funnel/expander made a big difference for me when loading loading heavies.

[John McCorkle]

https://www.uniquetek.com/product/T1736

This powder funnel/expander made a big difference for me when loading loading heavies.

I use the powder through expanding mandrel from 38 s&w does in my 9mm for cast....I had to polish it up really well with very very fine grit then polishing compound but it does a great job of getting a bullet to seat without swaging diameter off....and as long as the taper crimp isn't too much I get better fit in the bore, better accuracy and more confidence (only issues I ever get are particularly thick walled 9mm range brass ...and there just isn't anything I can do about that)

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