I have a new Marlin 444 that I'm handloading for and I want to use a 300+ grain bullet. I found a Lee bullet mold for a 310 grain bullet that has the crimp grove positions so that the overall length of the round is fine. My problem is that when I try to chamber a dummy the throat is too short and the rifling starts to engrave the bullet before the chamber is closed. So, I was thinking about sending the dummy round out to get a reamer made to lengthen the throat. Question, do you think this would destroy the great accuracy this rifle has with shorter 270gr Speer gold dot bullets?

Thanks
Clint

Clint;
I have a new (2yrs old) Marlin in 444 also! I experienced the same problem you have and I think that I will try shortening the cases so the bullets don't engage the rifling and see how that works! I cast the 240 grain Keith type SWC and I noticed that with this bullet loaded in the case, that the rifling is engaged almost to the case mouth. I know a lot of guys on here want to engage the rifling, but I think that this is too much!
My rifle is the Marlin 444P, it has an 18 1/2 inch barrel!

Hey Clint, If you don't have a Marlin Owner's Manual, contact them and get one. The reason is because the Action is going to dictate how long the overall cartridge length is in order to be able to cycle properly from the magazine without hanging up.

I can't lay my hands on my Owner's Manual at the moment, but I believe the MAX OCL is 2.570" < !--color-->, irregardless of the bullet.

Does your 310gr bullet engage the Lands when the OCL is 2.570" or less?

...

No way to know if it would mess up your current accuracy level with the 270gr Gold Dots. If it was me, chances are it would.

The previous suggestion to shorten the case a bit is a good one.

I just got to looking at some of my 444 rounds and I think I know what's up with this!
The cannalure is located almost at the ogave of the bullet and therefore it starts to curve immediately and thus misses the rifling!
As posted in one of my earlier posts under "big bores" these chambers are not as long as the old ones used to be. I used to use this very same bullet in the old 444 that I had when I was in Alaska in the 80's and it didn't even touch the rifling!
I don't know what the distance is, but I do know that the case mouth on properly trimmed brass comes very close to the rifling in these new rifles!
I think as I said before, the easiest fix would be to shorten the brass a little more, or maybe go to a "smith" and have him ream the rifling just a shaver!