Full Form sizing .375 and bullet selection

[luv2shoot]

Just starting in the club of FF SML. And what a learning curve. Thank goodness for this board and the posts.
Project: 700ml action with a  McGowen .375 1-12 SS BBL and ASG bp.

I've been trying  FF 'ing a 270 .375  bullet that I bought from Midway ( I think they are Hornady ) that has a cannelure. Once FF'd it starts loose at the muzzle then gets lodged about 4" down the barrel. So I "squeezed" others until one would slide the entire length. Problem I found  that is was very sloppy at the muzzle. Not wanting to gtab a land. First thought is a barrel issue.
So I'm wondering if it was my FF'ing technique. Thought maybe this bullet was springing hack or maybe I was putting to much pressure on it and causing it to "banana curl" slightly.
BTW using a SWinglock FF die.
Tried a 235 Speer Hot Cor. Sized easier ( I guess a thinner jacket plus no cannelure to squeeze)  and they  entered  much better. Still loose at the muzzle slightly. 
My next thought is to try some 9.3 mm bullets.
I read about knurling then sizing.
Thought if I sized my .375 bullets to small, then knurled and FF again might work. But a lot of work. Sabots are looking better all the while.

I did lap the constrictive areas. 

Will a 375 shoot smooth formed accurately?


Might just have a poorly made barrel . Will review posts suggestions and comments.

Greg

[super7]

I would talk to McGowen about the inconsistent barrel and ask about a replacement. It is better to be loose at the muzzle vs the breech but I would rather it be consistent all the way. When you say sloppy at the muzzle. Is it so loose you can spin it and it not grab the rifling or just loser than lower down. If it is loose but grabbing the riflings you may be OK because the bullet will expand to grab the riflings. Remember powder fouling will tighten things up also.

[luv2shoot]

Ut oh. I posted this in the wrong section. Sorry.

[Dave W]

Never tried the 9.3mm's. Was going to get some and knurl, then full form, just never got around to it.

Single pass sizing or multiple pass sizing?

My Kreiger .375 is choked on both ends, loose the majority of the barrel, shoots fine. Irks me to no end that it isn't consistent end to end, but have to make do with turd barrels sometimes. My .442 Mcgowen had a tight spot just above where the bullet seated. Had to size bullets for that one spot in the barrel, loose the rest of the way, it shot great.

[jims]

My Kreiger .375s were not consistent either. I have a .375 Brux (as I understand as I got it used) that is very consistent and takes unsized 9.3mms very well. Have not had a chance to shoot it however.

[rob67]

Yeah my Kreiger 375 is loose at the muzzle. Cut 3.5 inches off to get rid of the loosest part. It shot ok after that, just not great.I got tired of it a put a Brux on that is great.
If you can get McGowen to fix it I would do that. It'll save you some headaches.

[luv2shoot]

Rob67, Thanks for the reply. I did have a conversation with McGowen's smith. Yup it might be going back. Never have I tried so many bullets without firing a shot LOL.
The idea of cutting the barrel down and recrowning is appealing.
I did buy some 9.3 mm to try. Loose as expected. But gave them a good knurl and they grabbed, Might use them to fire lap.

[luv2shoot]

I do believe I have found the problem. I have tried more combinations of bullets,bullet sizing than I care to.
This is a McGowen 1/12 375 SS bbl as I might had indicated b4.
I had it sent to their custom shop for the barreling work.
Size any bullet. Enter it into the barrel and it gets to hard to seat any further about 3.5 " from the muzzle. Lapped barrel especially in the "tight spots" . Need carpal tunnel surgery now. . 
Still no good.
I turned a FF bullet around and entered it point first. Slide right down NP.
I checked the FF bullets rifling  engraving. I found the groove cut deeper on the left sides vs the right sides. Like a ratchet cut sort of.
 
Having an epiphany about this I tried FF'ing a Speer 235  .375 upside down .
Came out looking like an old glass milk bottle but usable to test. Deeper groove on the right now of course.
Entered into barrel.
Slid like I expected to. About 15~20 lbs rod ( est. ) pressure and no tight spots.
Ouila'

The original barrel drop was sent to the FF die maker I have to assume without the muzzle end being marked.
Plus being from an un-contoured blank I'm not sure which end was cut. Being a regular button rifled barrel I wouldn't think this an issue.
 To me it doesn't say much about the rifling button that was used. Enlighten me if I'm wrong.
Anyways I still have more of the barrel drop and the FF die maker is coming to my rescue.
Sending die back tomorrow to have a new insert installed.

[Deleted]

Have you tried marking your bullet before FF sizing then indexing to find which land to load of?

[luv2shoot]

I did.  Marked a groove on the bullet with a fine tip sharpie. Then marked the grooves at the muzzle numbering them. Thought maybe a  groove / land being out of porportion..

Problem was still as I indicated earlier. 
I did forget  to mention that I did this in my earlier post.

Thanks for asking.