Hornady L-N-L modified cases ... sometimes you have to make your own

[MCMXI]

I received a new rifle this week chambered in 6.5x47mm Lapua. I ordered a bunch of brass and some extra dies which arrived yesterday. I have bullets, powder and primers on hand so this afternoon I was thinking about putting together some handloads and was kicking myself for not ordering one of those Hornady L-N-L modified cases to measure COAL for different bullets. I have lots of those for different cartridges, but it turns out Hornady doesn't make one for the 6.5x47mm Lapua. Oh well, luckily I bought a 5/16-36 UNS tap last year so that I could make a modified case for the 6.5 PRC and it came in handy again today. I'm no machinist but this is an easy job, particularly once you figure out how to hold the case. I have a decent drill press so it wasn't much of a challenge. I drilled an appropriately sized hole in the nylon or whatever the heck the orange soft jaws are made of and they did a good job of preventing the case from rotating during drilling and tapping.

I used a case that I'd fire formed in the new chamber but had to use a Redding shoulder die to minimally resize the case to make it easier to use. Based on the consistency of the chamber measurements I got this afternoon it looks like this modified case is a keeper.

 

[Walkalong]

Nice job.

 

[Varminterror]

It’s a shame Hornady/Stoney Point used an obscure thread pitch for their spindle, else I think more guys would be making their own Modified Cases. From where I sit, making your own modified case is THE way to use that tool, unless a guy likes doing a lot of measurements and decimal math.

These pics give away the whole trick though - drill a hole in the seam between two blocks to clamp the case, don’t move the drill vise, insert the case, drill and tap using the press, and bingo bango, 15min later you have a >$1 modified case which actually yields instead of paying for a factory version with incorrect dimensions.

 

[MCMXI]

It’s a shame Hornady/Stoney Point used an obscure thread pitch for their spindle, else I think more guys would be making their own Modified Cases. From where I sit, making your own modified case is THE way to use that tool, unless a guy likes doing a lot of measurements and decimal math.

These pics give away the whole trick though - drill a hole in the seam between two blocks to clamp the case, don’t move the drill vise, insert the case, drill and tap using the press, and bingo bango, 15min later you have a >$1 modified case which actually yields instead of paying for a factory version with incorrect dimensions.

Exactly! It occurred to me yesterday that the best way is to fireform a case since it gives a much better representation of the measurement from the bolt face to the datum on the shoulder of the chamber rather than use Hornady's minimum SAAMI case which might not even be that. When the shoulder bottoms out in the chamber using the Hornady case, the position of the case head doesn't necessarily represent the location of the bolt face. I was all set to measure, shoot, measure, reload, shoot, measure etc. but the case was tight in the chamber after one firing so I made sure that a bullet could slip inside the case mouth, and bumped the shoulder back .001" so that the case would go in/out of the chamber easily. I measured 10 bullets (COAL) in the modified case and only had a variation of +/- .0005". More consistent than any Hornady case I've used.

As for the blocks to hold the case, I thought of using some rosin but it wasn't needed. Those vice blocks are somewhat compliant so I drilled a hole slightly smaller than the case so that I would get enough compression to hold the case securely. Since there aren't an infinite number of case diameters I'm sure I could use the same hole for a number of other cartridges if needed.

BTW … I used one of my girlfriend's cases … that I bought for her three years ago … rather than one of the new 300 pieces that I just bought. She'll never notice!!

 

[rskent]

Just soldering works pretty well.

 

[Blue68f100]

Nicely done. I looked at theirs and decided to make my own setup.

I made mine using the std 1/4-28 NF tap. The hardest part was getting the threads on the brass tubing to start straight.