700 Vs .308

[sundog]

Chargar, I got to dinkin' around with an idea. I had a Lee 312-185-1R SC on the shelf for I don't know how long. So, I lee-mented it and cast a bean can full just for grins. I ran the first one through a .312 as they were .312 by .314 and it came out .312 all the way around. It would not start in a fired case. Hmmm, says I. So, I changed dies to a .311, and it did not change the diameter. I loaded one anyway with a little flare to start it and kept trying to chamber it to find the right length. The load is 25.5/5744 and dacron. Okay, chambers good, nose lightly engraves. I went ahead and shot a few like this at 50 yds and they did just fine. Very clean necks and primers just barely starting to flatten. I went back to the loading bench and inspected the cases. Now, a .312 boolit is a slip fit in the just fired cases. So the same cases previously fired with either 165 Sil or 311299 the 312-185 sized to .312 would not fit. But, after firing the 312-185 another is a slip fit.

So, the question begs, just how big is the throat in these rifles? Have you checked yours?

I suspect that next weekend I will dig out the Fat 30, that I haven't yet used, and cast some of them for a trial.

btw, the 312-185 just isn't anywhere close enough for me to use in my No 4 Mk I. I can stick is nose first in the muzzle and it just rattles around. The Fatter 30 is and I use it in the Brit, but is probably to big for a 'normal' .308 bore. Also, I have had good success in a scoped 03 sporter with a full sized 314299 (sized .314) and IMR 4064. Fill the throat.

I guess the gist of all this is that I was a little suprised by the results of the fired neck in the 700 - I would have thought it might be a little tighter. Maybe it's just my copy. Perhaps a chamber cast. Just trying to find a way now to fill the throat. sundog

[felix]

Corky, try 5 shot groups with different sizes. Start with fattest that will fit, using the magic marker indicator all over the neck. Should see partial circular scrape at absolute max (for low pressure load). Don't use the fired case idea because of the various spring backs in your brass samples. Usually, a smaller diameter than max will shoot best because of the lube buildup at the case-end and boolit junction. That's why 5 shot group rather than 3 shot. ... felix

[Bass Ackward]

So, the question begs, just how big is the throat in these rifles? Have you checked yours?

I guess the gist of all this is that I was a little suprised by the results of the fired neck in the 700 - I would have thought it might be a little tighter. Maybe it's just my copy. Perhaps a chamber cast.

Just trying to find a way now to fill the throat. sundog


Corky,

Dan at Mountain molds was using a bullet that tapered from .318 to .308 in a 308 bore. That filled his neck. Eventually his throat opened to accept that. Now he is going to rebarrel.

Mine neck fills at .314 unless I ream brass. But my ball seat in the throat is .310. I size .3095 to be able to chamber a one diameter slug.

So are you trying to fill the ball seat in your throat or are you trying to fill your neck?

[felix]

Got to fill both, BA! ... felix

[slughammer]

For a 30 bore, you can knock a 38 cal pistol slug up into the chamber neck and throat to get a good measurement of the 2 diameters. Pure lead SWC or RN is best. Lots quicker than a chamber cast if only finding diameters. Just mark the rod/dowel for depth and adjust on the second or third try.

[Bass Ackward]

I .... don't know Felix. You know me.

My most accurate load to date is a rock hard 311284 that is undersized and outta round at .3075 to 3085 in a 308 bore. Just jam that nose where it's supposed to be, using 20 grains of 4759 with a WLP primer. Holds 1/2" today, tomorrow, and next week. 3 shots, 5 shots, 10 shots. Boring.

I size .3095 if I want to step on it. If I seat into the lands, larger than that and groups move above MOA.

The harder the bullet, the closer to bore I want to be.

[felix]

Rock hard works in everything, unless you cause obturation and/or knock the boolit out of line because of the neck slop. It appears your powder speed is just about perfect to get that boolit out of the neck before the sh.it hits the fan. Making a fatter "bore-ride" area will definitely work against you in this situation. Of course, you can get a fatter neck round with fatter case necks. Might help if the copper is soft enough to expand quickly enough. ... felix

[9.3X62AL]

Sundog--

Your Lee 312-185 sounds like the clone of my mold of same name. I run mine through a .311" sizer that gets the boolits right at that diameter, and run them through a Win 670 that shoots very well with this critter or the #311291 sized at the same .311". This is the 2nd M-70 in a row with a .311" ballseat/throat, the first being the 1948 variant now being used by my nephew.

Both rifles shoot Nosler B-tip 165's about .7-.8 MOA, so the j-words don't seem too bothered by rattling around on their way to the rifling leade. While life would be a lot less complicated by use of the j-words, it would also be a LOT more expensive--and boring.

[sundog]

Well, I was wanting to fill the neck and set the boolit into the rifling. Of course, if that doesn't work then I do something different. I just don't see why in a factory gun the tolerance can't be a little closer to start with, especially one that is touted as a varmint gun.

I've already got another load with a 311299 which sets into the rifle that works pretty good. Just trying some things to see if can do 'mo betta'. Besides, if the Fat 30 works, it could be a candidate for HPing, kinda like the thread ongoing.

Al, 10-4 on the copper clads, makes it so just about anyone can shoot, knida like putting a automatic tranny in an automobile so just about anybody can drive. Not that it's all bad, but ya just gotta have a little finesse. sundog

[sundog]

Well, the Fat 30 with 42.0/DP86 (that's a caseful) is looking good enough to load a bunch more. After a scope adjustment I had 4 rounds left (started with just 10 of this load) and they all went in the 10 ring of a SR21. One at 2 o'clock scratch X and the other three vertical on the other side of the X at 10, 9 (almost X) and 8 o'clock. Brass is clean, bore is clean, and target is clean! I'll play with this'un a bit.

Bass, about throats opening up. If ya got a good load, shoot it! Barrels can be set back or replaced. Accuracy is interesting (although boring after awhile). sundog

[sundog]

Okay, here's one that looks like a keeper. 30.5/4895 and 311041 WQ WW/Cu babbit. Yesterday, 2 5-shots groups at a hunert, both sub 1-inch. Speed is about 2000. That rifle will not shoot jacketed better than that. A few years ago Felix gifted me some LBT 170 FN which are similar but a little sleeker. They get tried next. Seems like this profile fits the throat pretty good on this gun (from the factory bbl). sundog