Should I engrave rifling or back off.

[wallenba]

I'm trying a C312-185-2R in my 30 Herret Contender carbine (16-1/4" barrel). I seated the boolit so that the base of the gas check sits just below the neck. This puts the crimp groove inside the case neck a bit. I just ironed out the M die flare, no real crimp. The charge is 6.8 grains of Trail Boss. My only concern is that the bore ride is engraving in the rifling a bit. They are cast of Lyman #2 alloy. Not so much that it won't extract or be too hard to close the action though. Is this an OK practice for cast boolits? I know it's a no-no for j's. I just need a little confidence building before I pull the trigger on them. Thanks.

[Blammer]

Slightly engraving or "kissing" the lands is the preferred method to obtain accuracy, including jacketed bullets.

We have had several buy's for bullet moulds that specify that the cast boolit nose DOES slightly engrave when seated.

You'll be just fine.

[wallenba]

Slightly engraving or "kissing" the lands is the preferred method to obtain accuracy, including jacketed bullets.

They are leaving marks I can snag with my fingernail. Still OK?

[DLCTEX]

I engrave boolits in my Marlin 30-30 with good results.

[Blammer]

Yes still very good.

My FAVORITE load and most accurate is a 311284 that if I take out the round from the chamber you definitely see engraving on the nose, most of the time at least 3 or 4 of the lands and you can snag a fingernail on them too.

[wallenba]

Ok , thanks guys. I feel a bit better now. I put a lot of effort in making 100 new cases from 30-30's, only to find this out after seating them all. Would hate to have to seat them deeper over the same charge.

[geargnasher]

Seating to engrave the rifling is the next best thing to breech seating.

Gear

[runnin lead]

Shoot them & find out. you can also seat some .005 & .010 deeper
& let the gun tell you what it likes.
Sometimes things can be funny in that way.
It keeps things interestimg or just helps add to the insanity.

[noylj]

The only concerns are:
1) start at the starting load and work up
and
2) in general, the bullet should not engrave so much that if you pull the round out, it leave the bullet behind and the action fills wit powder.
With J-bullets, best accuracy is often just a hair off the lede--but every barrel makes its own rules.

[cbrick]

I have many molds that cast a nose that engraves and they shoot fine. Think of it this way . . . They are called "bore rider" for a reason. I seat many of my cast bullets this way, I'll seat it deep enough that the check is below the neck in the shoulder area but never so deep as to get the bottom lube groove below the neck, many times with longer bullets there is little choice but to engrave the nose with the rifling.

I have a perplexing problem with this though, I have NOE 311365 with a .305" nose and NOE 311284" with a .301" nose (both noses measured with a mic). Loaded in the same lot of cases and chambered in the same 308 they both engrave the nose of the bullet the same when seated to engrave on the full diameter of the nose. When I looked at that I didn't believe it so I loaded 6 dummy rounds of each and chambered them all, if there is a difference in the rifling marks I sure can't see it. Very strange indeed.

The rifling engraving the nose should help align the bullet with the bore, all of the rifling marks should be the same all the way around the bullet. If they are not the bullet is not chambering concentric with the bore.

Rick

[cbrick]

Just re-read the original post and since he is using a contender barrel I'll add this. The bullet "could" be chambering concentric with the bore but if the rifling marks aren't uniform all the way around the bullet it could very well be uneven rifling. Contenders are famous for this.

People that own Contenders should not be allowed to own or use a bore scope, that about to throw up feeling isn't very pleasant. Not a knock on T/C, I have several excellent shooting T/C barrels but they aren't known for their great chambers or throats.

Rick

[wallenba]

Just re-read the original post and since he is using a contender barrel I'll add this. The bullet "could" be chambering concentric with the bore but if the rifling marks aren't uniform all the way around the bullet it could very well be uneven rifling. Contenders are famous for this.


Rick

Not to worry Rick. My barrel is from Match Grade Machine, and the rifling is even all the way around. It started life as a Contender Super fourteen handgun.