I have a Win. Mod. 70 varmint in 243. I recently tried to measure for seating depth with a C.O.L. tool from Stoney Point, when I removed the tool from the chamber the plunger was protruding above the case. I repeated this several times with 2 different bullets. I used a 55gr Nos. BT & a 95gr Combined Tech. BST. the results were the same with both bullets. Could this be an indication of severe throat erosion?

Yep, but you`ll need a bore scope to know for sure. If the rifle still shoots well I`d let it go for now.

I found a bullet long enough to measure to the lands with my stoney point tool. I came up with 3.048" OAL. The bullet just barely remains in the case at that length.
It is looking like I will have to do something. Any suggestions? I was thinking of having the chamber end of the barrel faced off a few thousandths, rethreading & rechambering.

Setting back the barrel with associated rethreading and rechambering will work. But it will leave your inletting a bit loose in the forearm area. Purely cosmetic, but I don't know if that matters to you??

Do you strictly know that the long throat is a consequence of erosion?? A lot of chambers are pretty long throated as they come from the factory. Mind you, erosion does not help either. The 55 grs .243 bullet is a pretty short one. Could you use a heavier bullet?? A FB bullet will provide more bullet for the neck to grip than a BT. Also, measure your chamber length, make sure you don't trim your cases any shorter than what you have to. Most factory chambers will allow brass to be a lot longer than SAAMI specs.

How does the gun shoot?? Some guns don't mind a bit of a jump. If it isn't broke, don't fix it.

Finally, the ultimate measure: get a new custom barrel put on the gun, chambered with a reamer for which you specified dimensions yourself, so you know exactly what you get...
- mike

This particualr rifle is a model 70 Winchester that was made in 1964 & has the original barrel. It is the varmint barreled version. I don't think that the inletting problem will be very noticable because of the very slight taper. I could not use the 55gr BT or the 95gr BT to obtain a measurment. I had to use a 105gr Amax to even be able to get the 3.048" OAL measurement I listed in my last post. As far as accuracy goes, I have not tried any hand loads yet. I have tried some 100gr Rem. Core-Lokt's & Win. Supreme 55gr BST. Both would not group at all at 100 yards. I could not keep them on the target. That is why I started looking for a problem. There might be chance that I could get the 105gr hornady's to group, if I seated them really long, but I think I would have to fire them single shot. I don't think that they would fit in the magazine. I may try that before I do anything to the rifle. Just to see what would happen. Try some seated to magazine length & then some seated longer.

well, my first ?? is do you have an approximate round count? if the round count is relatively reasonable, then I doubt throat erosion has taken up that far. Does the patch feel rough and like it is dragging for the first few inches in front of the chamber? if not, then I am doubting erosion even more.

Many factory chambers are looooong. If yours was one of the first years of the 243, then the twist was heavy for the bigger pills, and may have been throated for the longer pills, then the little extra "lawyer" length puts you where you are now.

If you can get 1 bullet dia in the case, seat it there and see what happens.

Throat erosion doesn't usually cause the kind of poor accuracy that you are experiencing, nor does it typically "eat" away enough of the rifling leade to measurably lengthen the freebore. I suppose that it could, but that would take A LOT of promiscuous shooting. I have a .264 Winchester that is 40 years old this year and has had no-telling how many thousands of rounds through it (some injudiciously loaded to excessively high pressures in my more aggressive youth). It has visable throat erosion, yet, other than requiring about 1% more powder for the same velocity as in the early years, it groups as well as ever (which has always been good).

Your barrel may simply be "worn out" (a combination of eroded throat, worn riflings, hard-to-detect pitting and erosion, and possibly worn or uneven crown) and need to be replaced.

Otherwise, there's always (1) bedding, (2) scope mounting (3) internal scope problems that can cause you to "not keep them on the target".

I took the rifle to a gunsmith, he looked it over & told me it had an excessive amount freebore. He told me that with the way it was shooting it probably needed a barrel. I am going to try some 105gr bullets seated as long as I can & see what happens. If it groups doing this I will consider a new barrel.