Design or suggest a boolit for .338WinMag, sketch of throat provided

[PWS]

Hello All,

Just spent the last few hours slugging, mic'ing and drawing up the dimensions of a .338WinMag throat with the intent of spec'ing a boolit to fit. Purpose would be mostly practice for hunting out to 200, maybe 300 yards so it would be nice to break 2000fps with 1-2moa so we'll start with a gas checked design. Flat noses are good but not too big to cause feeding problems, ballpark .180-200" dia?? And, no need for a light slug, I'm already having decent luck with sized down 357 slugs, particularly Accurate #360165C over 10-15grains of medium pistol powder will produce 1" groups at 50 - good for rabbits and such - so something 250grains +.

Rifle is built on a H&H length action so there's lots of room in front of the case and that might be a good thing as it's had at least 2500 jacked rounds through it and the lands appear to be worn down a bit.

Open to suggestions, Thanks!!

(pic deleted - basically showed dimensions of worn throat)

[Doc Highwall]

What weight is you hunting bullet? I would start with something close to that weight.

[45 2.1]

PM BABore and see if he has a 338 mold left over from BRP molds.

[PWS]

Dredging this up from a few months ago. Got a design drawn up with Tom from Accurate and have mold in hand (he's good!)

http://www.accuratemolds.com/img/bullets/detail/34-230B-D.png

Now that I have a bullet that's a tight fit in the throat (confirmed it with a couple of dummy rounds seated in a .458Win die), any suggestions on how to better seat a .345" bullet in a .338WM case? I'll be neck turning brass to ensure there's no chamber interference and will turn an oversized expander plug for a Lyman M-die but need a seater. No way will these bullets fit in a standard .338WM die. A .348Win die would work at the neck but the shoulder is too skinny. .358 Norma Mag or .350 Rem Mag is good at the shoulder but will be a bit more sloppy at the neck. Might have to lap a .338Win seater unless somebody has better idea...

[PWS]

Redredging again after work kept me away from my guns this summer but back at it...

First, thanks to Tom at Accurate and Buckshot here on CB. After a bit of correspondence with Tom, BABruce and 45 2.1, I got a design drawn up that fills the worn throat as well as I could measure/spec (see link above). Tom's golden nugget comment during design was "any lead not in contact with steel is a liability". Interestingly enough, the front half is pretty much the same style as BRP/45 2.1's design to fit the rather large cone shaped .375H&H throat: http://castboolits.gunloads.com/showthread.php?157237-MiHec-375-H-amp-H-HP-GC-Boolit-2-or-4-Cavity-Brass-Cramer-or-Solid. I spec'd the base differently and went with three smaller lube grooves. With the oversized dimensions of the design, Tom suggested spec'ing the 'check shank for 0.348 checks instead of 0.338 checks. This was also good advice!

While I was gone, Tom cut the mold and Buckshot supplied a 0.345" sizer die. I also ordered a Forster Bench Rest Seater and after getting back from work, opened it for the oversized slugs. The bullet seat got bored out to 0.345" I.D. and the inside of the seating stem was turned to fit the cast bullet much better than the steep cone they supply for spire point jacked slugs.

Using water dropped range scrap, White Label C-Red, Hornady checks, and 0.367" neck sized brass, accuracy has been outstanding and easily attained, no doubt the result of tight fit in the throat. This is in spite of the short-neck large-capacity case, the tight 1-10 twist, and the rough, worn and oversized throat.

I've only tried four powders, Universal, BlueDot, IMR3031, and H4895. Maximum velocity with accuracy so far has been ~2kfps and a bit more lube capacity might help although this is plenty of speed for my needs. 17.5grains of Universal clocks ~1525fps and will group five slugs into less than 3/4" at 100yds if I do my part. 30-35grains of IMR3031 runs between 3/4-1" at 100 with speeds in the 1800-1900fps range. 20grains of Blue Dot runs just under 1600fps but isn't as quite as tight a grouper as Universal. 40-42.5grains of H4895 will hover around ~2kfps and 1 1/4" at 100. Accuracy goes south and fouling rears it's ugly head with charges higher than these.

A few interesting observations,

1. Universal and Blue Dot loads almost always leave a dark shadow just forward of the throat. I think it's a light lead wash as the result of gas erosion. Even with the tight fit and gas checks, I think I'm not getting a complete seal in the throat with these quicker powders. Softer slugs only make the situation worse, leave excessive leading at the muzzle, and result in groups in the 2moa range.

2. The heavier loads with IMR3031 and H4895 leave the bore mirror bright the whole length. I've also had NO trouble with hang fires with these charges with no filler, magnum primers, opened flash holes or other tricks. The same loads in a two different .375H&Hs were scary click...BANGS! I'm guessing that the oversized slug presents enough resistance that it does not stutter start.

3. Although cold start issues are common with C-Red lube, it does not seem to be a problem in this set up. Perhaps I could gain a few hundred fps with an "extreme" lube but C-Red seems just right in this rifle with these loads. It would be interesting to try BRP/45 2.1's lube design.

[geargnasher]

"Any lead not in contact with steel is a liability". That's pretty much it with static throat fit.

"Extreme" lube, as being developed by some of us here, is meant in the same context as Hodgdon Extreme rifle powders. That means reliable consistency in extreme heat or cold, storage stable, and generally robust. It doesn't mean it will make your boolits go faster (although some types of lube do this), and it doesn't mean that all the benchrest guys will switch to it.

Keith grooves on a rifle boolit like a soft lube, but Tom can't cut grooves like 45 2.1 likes.
Gear