Home Forums Hunting & Shooting Ask The Gunwriters follow up on "unexpected reload pressure" thread my P-64 M-70

On reading the thread about the "unexpected pressure" that developed in another campfire members rifle I checked my Dad's old Pre-64 Model 70 .270 that I inherited. This rifle has always shot OK and never had issues with factory ammo BUT the cases for it always had to be segregated from the other .270s in the family as it would barely chamber them. The rifle would also never take the loads like the famous 60 gr of H4831 and 130gr bullet load with out showing pressure signs. We used 56 grains and a Sierra 130 for a lot of years.

Since getting the rifle I haven't experimented with it too much, I just hunt with it occasionally for sentimental reasons and want to keep it in good shape in case my brother's grandson shows interest in it someday. I have shot some mild handloads assembled in new brass and have shot some factory ammo in it for zeroing and hunting. I tried the "bullet into the neck test" with a Hornaday 140s and found it wouldn't fit in 80 to 90% of the once fired cases.

Is outside neck turning all the cases to be used in the rifle to create more space in the chamber upon firing the best remedy? I don't plan on wearing out the barrel on this particular rifle so getting 100 cases prepped for it is all I will need. Thanks in advance for the information!

It could be two things.

One, the case neck can be too long, causing it to crimp in the rifle's throat. When this happens, it takes more energy (pressure?) to get the bullet started, because the mouth is jammed into the throat and cannot expand to release the bullet. The solution is to trim the cases.

Two, the case neck can be too thick. A thick neck has no room to expand, causing the same problems as above, but for a slightly different reason.

If the brass is too long, trim it and use a chamfering tool to bevel the case mouth.

If the neck case walls are too thick they will have to be either outside neck turned or reamed, plus they can be too long, also.

Check both.

Phasmid,

Outside turning will work, and unlike inside neck reaming has the additional benefit of evening out neck thickness, which may help accuracy.

But if the problem is the "dreaded donut" (and that's that most neck-thickening problems amount to), you must turn the neck all the way down into the beginning of the shoulder. If you haven't turned necks before, it's also easy to turn them down too much, so your sizing die doesn't reduce the neck diameter enough to hold bullets. If you're using collet or bushing dies this isn't a problem, but it can be with standard sizing dies.

If you don't have a neck-turning setup, it will also cost some money. An inside neck reamer is pretty cheap, and will definitely solve the problem.

How about the inside reamers made like a sizing die with a close fitting reamer coming in from the top?

That would sure work--but wouldn't be as cheap!

John,

The cases were brand new Remingtons, checked for length and prepped before loading, The factory loads were Winchester and Federal so there was no dreaded "doughnut" formed yet. I guess I need to shop for a new reloading tool. I doubt it will take a lot of reduction. The rifle has always chambered factory ammunition without difficulty as far as I know. Thanks for info!

Scott

I think some Cerrosafe might be a good investment here. Get a good pour, you will learn a lot about your chamber that you might want to know.