Tight Throat?

[Nvhunter92]

No I have not tried the stripped bolt method.

I can close the bolt on that bullet at 3.59 and I think the short picture is 3.47 but I can't remember exactly now. It is a 178 amax that's in the pictures above but a 220 smk will do the same thing.

So I found that if you remove the firing pin assembly and the ejectors your bolt has no tension whatsoever and just "flops" around for lack of a better word. This allows you to really get a feel for what the bullet is or isn't contacting during chambering. Here is the link to the video that talks about the method...it really helped me out.

 

[TwoMore]

I just took one of my fired cases from the problem ammo, neck sized it in my gold metal match die without the expander (I was previously using a standard rcbs neck sizer with expander), seated a bullet at 2.685" with my GMM seating die and chambered the round with the firing pin and ejectors removed. The round chambered with very little pressure and the bolt lifted and moved rearward easily (no banging on bolt to get it back). There was still very very light scratching of the bullet at roughly the same distance from the neck but it was not nearly as deep and hardly noticeable. So I think I have the problem identified...1) my old neck sizer was inducing significant runout which made chambering and extraction difficult 2) my throat is on the tighter end of normal thus the bullet is still contacting it ever soslighlty before it reaches the lands

Does this sound right?

Is there anything wrong with having a tight throated rifle?

looks like the freebore area is where the scuffing is which is going to be pretty tight (+.0005 over bullet Diameter) .00025 per side. any runout of the bullet and case and it will rub. I usually accept .001 to .002 run-out on loads so even there the free bore will be lining up the bullet heavy on one side. I have a wsm that will leave the same mark as yours but it is always on the right side of the chambered round and when I took out the ejector it quit. a .314 fired neck diameter wont mean that it is a 314 neck chamber, the brass will spring back. my .3164 no turn tight neck chambered wsm's brass usually measures about .315 to just under after firing and .312 loaded(turned brass). I would definitely invest in a concentricity gauge. i was just lookin at my huntin rounds that have been in and out of that chamber all season and they have some rubbing in the same area. i just took some pics. the center round got dropped it looks like and has about .007 runout, I chambered it and put it in the pic. this chamber is .168 fb. none of the rounds are hard to chamber but they are reloads bumped .002. I am not starting a bump or FL sizing whizzing match lol I neck size some too lol but I can see where FL sizing may eliminate hard cambering here and let the free-bore line it up.

 

[kfreeze]

I have the same thing going on with a custom 300 win mag. Same mark on one side of the bullet. What else I find strange is 3.59 is max length but I can still see rifling marks on the bullet even when I seat them down the 3.45-3.48 range. I've had a hard time finding a max oal. Ive had to bang out several bullets from the barrel that have gotten hung up while experimenting with seating depth. I have never had these issues with anything before. The gun shoots 2-3 moa average no matter what I try. Sorry for a hijack of your thread but my current battle as well.

Almost sounds like the reamer that cut that chamber was really worn or cut wrong dimension causing it to not cut out all of the rifling in the throat area.

 

[kfreeze]

View attachment 90794 View attachment 90795

Looks like the whole throat is too small.

 

[just country]

morning, not second guessing members. this looks like
the chamber has a short throat?? I have a 6.5 rem.
mag. that has the same problem. I went to a bullet
with a longer ogive. has no problem with
accuracy. just me GBOT TUM