How much freebore does a CIP chamber have?

I finally got around to measuring bullet seating depths a barreled action I picked up on AR and it's massive - like seating the bullets at 3.7"+ which isn't possible.

I read some measurements wrong. Looks like freebore is .318" - that's still pretty long. The 280 Rem is .179"

Dunno about the 7x64 but my Zastava 9.3x62 has much more throat than I can use without exceeding the magazine length.

wow, CIP chamber spec is
34mm!! aka 1.338”
I should note no straight sided
freebore, only leade angle 0°17'11"
CIP spec also shows length from
case head to lands 3.8”
Steve

I think this came about to fit heavy round nose bullets.

quote:

Originally posted by steve505:
wow, CIP chamber spec is
34mm!! aka 1.338”
I should note no straight sided
freebore, only leade angle 0°17'11"
CIP spec also shows length from
case head to lands 3.8”
Steve

That's what I found as well (34mm), but then another article stating a calculated freebore based on the angle - that's the # I posted above. We'll see how it shoots! I can always set the barrel back and extend the mag to run a 3.425" OAL for the ammo.

you got me curious. using the CIP specs, below shows the
calculated leade angle which agrees with the spec.
7x64 leade
length 34.000 mm
dia. 1 7.320 mm
dia. 2 6.980 mm
delta 0.3400 mm
taper 0.0100 mm/mm
angle 0.286 deg
deg 0
minute 17
seconds 11.3

Saami also shows the same specs., so think it is good.
You might play with the CEB single feed copper bullets as
they might fit that long leade.

Idk, but in my experience, 7x64 tend to be deadly accurate, like a 308 .. shoot heavy bullets in it

i do recall a like issue, perhaps in the 90s (almost certain) during the initial 6.5x55 craze, as everyone was loving the cheap, low recoil swede mauser, and remington/winchester got on board with the round, but the throat/leade was shorter in the american chambers.. which, in some cases, lead to pressure issues in the american chambers and surplus/euro ammo ..

but it's been a minute, i could have all of that wrong

I bedded the barreled action in one of my "try stocks" this weekend. plan to shoot next weekend.

I will likely put the bottom metal from my Parker Hale ZG47 on it since it has a 3.450" inside length. And move the current bottom metal to a 275 Rigby I am building. I put a new drop bottom metal on my ZG47 to accommodate 4 down 8x68s.

I shoot three different 7x64 rifles at present, and have owned three others. All had throats with a leade so long that 140 grain bullets would be completely outside the case if seated to the lands. In my experience, it makes no difference. They all shot pretty good, regardless of bullet jump. After that experience I tend to disregard the over all length of the cartridge. Seating to the lands is unimportant if the throat of the chamber is concentric and not too large in diameter. There is so much about the wonderful 7x64 cartridge that typical American gun writers and reloading sources get wrong. The 7x64 can safely digest more powder while using the same bullets as the .280 Remington, with the same or better accuracy, reasonable pressures and better velocity. It's a better design that predates the .280 by decades. But USA load data sources continue to refer to "downloaded .280 Remington" data sources and seating bullets just short of the lands. Sigh.

The length of free bore isn't as important as the diameter of the freebore. If the freebore is less than .0005 over bullet diameter it will shoot well. This snug freebore will keep the bullet straight in the bore.
If the free bore is .001 or or .002 over then it might just shoot good, getting much over that like .005 or so you might start to see issues.
Depending on your use you can use cast bullets at a diameter to match or be .001 or .002 over your freebore diameter and get it to shoot well. As long as such a diameter when seated in the case doesn't expand the case neck to large for the chamber.

I have 3 7x64 rifles and all of them have very long throats and all of them are different. All three prefer bullets of 150 grs or more for best groups. I seat bullets out as long as the magazine in each rifle allows.

A long throat is another way to get an improved chamber as you can add powder..Ive found it an improvement it the 7x57 for instance..

The long free bore in the 7x64 and 7x65R (the rimmed version, which I have used for last 15 odd years) is there so can shoot the long almost rectangular shaped 173gn Brenneke type bullets for which it was originally designed. The fast twist rate is there to stabilise them. They hit very hard and in Europe 7x64 is used on everything up to Big Brown Bears and Elk ( what you all call Moose).

More details on the RWS ID Classic - https://rws-ammunition.com/en/...x64-id-classic-11-5g

I forget what these are called.

Look like RWS H-Mantles, will have a ring in the bullet jacket about where the casemouth is now, possibly not visible as seated inside neck. German attempt at an interlock bullet, were good bullets but now dropped from the RWS range.

Unfortunately the barreled action I bought (from an AR member that supposedly had 2 ACGG members work on it) was chambered to tight. So I have to solve that problem first. Sigh.

DUDE - that has to be frustrating

AH Sounds like it has a match grade chamber. Had one in 7X57, very tight. Gripped the bullet during a light snowfall, 28F. Polished up quick with a nylon brush wrapped with 0000 steel wool spun with a drill. 30 seconds at medium speed.

quote:

Originally posted by Austin Hunter:
Unfortunately the barreled action I bought (from an AR member that supposedly had 2 ACGG members work on it) was chambered to tight. So I have to solve that problem first. Sigh.