Krag .30-40 OAL/throat measurement

[Battis]

To get the OAL for a Krag cartridge, I measured the distance from the muzzle to the closed bolt face and marked it on a rod. Then I put a .311 (170 gr) bullet into the chamber and measured from the muzzle. The difference between the two marks was 2.96". Then I tried with a .315 (170 gr) bullet and the measurement came out the same (2.96"). I tried with a .308 jacketed bullet and it came out to around 3.34".
So...still wrapping my brain around the throat dimensions. If the .315 and .311 bullet enter the throat to the same distance, does that mean I could shoot the .315 unsized? (the bore measures .3095).

.311 - 215 gr bullets chamber and shoot well - I just came across a box of cast .315 bullets for cheap money.

[frnkeore]

Before you can say which one fits the throat best, you need to see how the nose engraves vs the front band. The throat size will be determined on the front driving band engaging the throat. If the nose engraves first, the bullet will need to go farther forward.

Frank

[Mk42gunner]

So...still wrapping my brain around the throat dimensions. If the .315 and .311 bullet enter the throat to the same distance, does that mean I could shoot the .315 unsized? (the bore measures .3095).


Not necessarily, it will depend on the diameter of the chambers neck and the diameter of the loaded rounds neck. You need to have a thousandth or two clearance for the brass to expand and release the bullet upon firing.

Robert

[Battis]

I was thinking about Char-Gar's point that the bore dimension isn't as critical as the throat dimension. Based on that point, a .315 bullet that chambers should be safe to shoot down the .3095 barrel.
Anyways, I loaded up a bunch of .311 rounds using 7 grs of Red Dot, and that seems to be the perfect round for my Krag - accurate out to 100 yds, no recoil, easy on the rifle.

[madsenshooter]

I've been sizing .314 for my Krag. .314 sized beat the same bullet sized .311 in the only test I've had time to do. The bullets I'll be shooting at Camp Perry are sized .314. High pressure loads in my rifles blow the necks of the Remington cases I use out to .315 ID, as I've mentioned before.

[jonk]

With every Krag I've ever owned, the necks wouldn't take more than a .311 bullet without neck turning. Most bores were in the .309 range so that wasn't an issue in principle. But then again, I've never really gotten any of them to shoot cast lead well and believe me, I've tried.

Most have also had very long throats; whether made that way or from years of shooting, I can't say. Some so long that even a heavy, long bullet such as the Hornady 220 or a similar cast lead wouldn't even touch the rifling, even when seated out all the way.

My latest thought for this situation, given the easy access to the Krag chamber, is to breach seat the bullets (cast lead only) to fit the throat, pushed forward by a hard wooden dowel glued into an empty case; then insert a case with a charge behind it. Breech seaters report that floral foam can be used to seal the neck of the case without raising pressure unduly.

Would be slow as can be, but could be conductive to excellent accuracy.

[Battis]

With 7 grs of Red Dot and the .311 - 170 gr bullet, at 50 ft, the groups on paper weren't that great. But, I hit the gong at 100 yds with every shot, usually right in the middle of the gong. With The Load of 13 grs Red Dot, I couldn't hit the gong. I think this rifle likes to be babied with very reduced loads, which is fine with me.
2.7 grs Red Dot in my Colt .38 Police
3.5 grs Red Dot in my Ruger .38/.357 (+P)
7 grs in my Krag...
Gotta love Red Dot.

[Der Gebirgsjager]

O.K.--educate me here. Please. I am a Krag shooter with a good dozen of them in various year models and configurations. The way I've always gone about establishing the length for the cartridge in any particular rifle is to finger start the bullet as it will be used (diameter) into a case previously fired in that rifle, insert it into the chamber and gently close the bolt. Open the bolt, measure the result and subtract .0002", then load them all to that length for that rifle. It seems to have worked for me, and I don't understand exactly what you gentlemen are doing here. Well, I do understand what, but not why.

[madsenshooter]

Sometimes it works doing as you do, sometimes it doesn't. There have been times I tried your way, but the bullet wasn't moving when extraction first started, but it would come along later, leaving me with an over length round that was difficult to chamber. It all depends on the pressure of the previously fired round. If it's high enough, or if the case was plumb full of 860, I get a neck ID of .315 with recent made Remington cases. This is with three different 92/96 rifles. 98s, above serial #213,000 or so are supposed to have a neck .002 smaller than the earlier rifles. Whether or not that is true probably depends on reamer wear in the case of the 92/96 or chamber wear in the case of the 98.

Jonk, rather than mess with trying breech seating, I just get a mold that drops a bullet with a larger nose than standard, like NOE's 316365 or 316155 and fill that throat up. NOE makes other oversized molds too. That Hornady 220 is quite tapered ahead of the crimp groove, I've found previously, can't find the one I have left right at the moment though.

[cpaspr]

O.K.--educate me here. Please. I am a Krag shooter with a good dozen of them in various year models and configurations. The way I've always gone about establishing the length for the cartridge in any particular rifle is to finger start the bullet as it will be used (diameter) into a case previously fired in that rifle, insert it into the chamber and gently close the bolt. Open the bolt, measure the result and subtract .0002", then load them all to that length for that rifle. It seems to have worked for me, and I don't understand exactly what you gentlemen are doing here. Well, I do understand what, but not why.

Did you mean .002"? 2/1000 I can understand. 2/10000 is a bit tight.

[Der Gebirgsjager]

Yes, I stand corrected in positioning the decimal. Two one-hundredths of an inch. Well, it seems to me that you fellows are telling the chamber how long you want the cartridge to be, rather than letting it tell you what it likes. Naturally, for the system I use to work well there has to be a reasonable amount of tension of the cartridge neck on the boolit. I want the back of the lands to push the bullet back into the case, and I know that it's made contact as marks will be left on the nose. If it's going to stick on the way out (extraction) and pull forward out of the case somewhat then there's a pretty good chance that the case neck was oversize or that there's a constriction somewhere, and a smaller diameter bullet or chamber polishing might be in order. But, different strokes...as they say. It works for me. Between slugging the bore and deriving a length this way I get good results. It's just about a "given" that .311 is a good place to start with Krags. A .314 or .315 will displace but will also raise the pressure. To avoid pressures that are too high in these 111-120 year old rifles you have to reduce the load to compensate for the bigger diameter bullet, with corresponding negative changes in velocity and trajectory. So they're still shooting Krags at Camp Perry? Want to borrow my M1-A?

[Battis]

I've measured the OAL the way you describe, too. I even cast a wax bullet that I used in the empty case to get the OAL. Basically, the length comes out the same either way. I didn't have a fired, unsized case to use with these new bullets so I measured from the muzzle back. I might try the .315 bullet with the reduced Red Dot load.

[madsenshooter]

"Want to borrow my M1-A?" I'd love to, but it would be a little out of place in the vintage match. I had to sell mine back in the 90s for college money. Bummer, cause it was a Devine made one and I wasn't aware of the value back then.

[Der Gebirgsjager]

Guess I feel kind of bad now. I wasn't trying to be facetious--I really would let you use it if you brought it back clean. But, with you being in Ohio and me in Oregon it would involve FFL complications; and like you explained, it wouldn't apply to your endeavors anyway. I've never been to Camp Perry, but would have liked to go. Many years ago (I'd wager before you were born!) I was on an Army Battalion rifle team in Germany and missed the cut to get to return to the US and shoot at Perry by 2 points. That was with the M1. It must be kind of a great experience to get to shoot where so many legendary riflemen have competed. Best wishes to you. Krags are still fine rifles.