2feathers

I have a 30 year old Rem.700(30/06) that I have put over 2000 rounds through.After purchasing it new, I checked the seating depth by placing a 150gr. head in front of a fired brass & then chambering the round. I reduced the length by 1/32".
The rifle shot extremely well for all these many years. However, I recently repeated the above exercise & the bullet was not pushed back into the brass at all. I used 150gr. & 165gr. bullets. It appears that there is excessive space between the shoulder of the round & the rifling. This may be due to wear.
While the accuracy of the rifle has not been affected, does this present a dangerous situation? Should I see a gunsmith? As best as I can tell, there does not appear to be a headspace problem.

Roskoe

This is not unusual. The throat is wearing, and allowing bullets to be seated outlonger before they engage the rifling. As long as headspace is OK and accuracy is acceptable, its not broke; although it may be half way or more towards being shot out.

sabotloader

2feathers

Roskoe - nailed it... could not have said it better. But then Roskoe as a gunsmith has a whole lot of experiance...

Throat errosion - normal occurs faster in some guns than others...

2feathers

Thanks guys for your quick response to my situation. You have put my mind at ease.
I guess I'll have to think about having my rifle rebarrelled if it starts to lose accuracy.

48thguns

Well for starters, you need to get an OAL gauge....1/32 of an inch is a huge space between the bullet and the lands, 50 thousanths is alot. No wonder you are experiencing erosion.....too bad cause it's too late now....the damage has been done. Good luck and regards, Rick.

PaJack

FYI...

http://www.larrywillis.com/OAL.html

Roskoe

Good article. When I build a custom rifle, I usually take the piece I cut off the muzzle end and run the chamber reamer into it until it just cuts the shoulder - then quit. The creates a guage that allows the handloader to calculate the overall length at which the bullet will engage the lands. But in the case of a factory rifle or a custom rifle where the reamer was not used to create a guage, the method described should work great. Thanks again. Roskoe.

Dan in Alaska

Thanks for the article PaJack. I like the idea of using the Dremel tool to slice the case neck. This probably works better than my low-brow technique. I use a fired case and ding the neck to make it slightly out-of-round, just enough to hold the bullet.

Roskoe, I like your idea of using the cut-off end of the barrel to make a case gauge. If I ever get another rifle re-barreled, I will ask for this.

Solitary Man

Sorry, but 1/32" is not a "huge" space between bullet and lands. 1/32"equates to about 30 thousandths, which is not a bad place to start (or stay at) at all.That's about where I normally start. As far as I know, throat erosion has virtually nothing whatsoeverto do with bullet seating depth.You shoot enough rounds through a rifle and the throat's going to erode, period.The bigger the case in relation to bore size, thefaster it will erode. Therefore, a .300 RUM will be shot out way before a .308 Win. will be, assuming neither is abused otherwise.

bigcountry

On my 300RUM's I had, I had over .2" jump to the rifleing. And it still shot sub.7MOA regularly. I started getting heat cracks in the neck after 500-600 rounds. And accuracy started falling.