17 Fireball case capacity change

[trotterlg]

I bought two boxes of 17 Remington Fireball factory ammo for a couple of reasons, first to get some brass because it is hard to find empty and second to use a factory round for cutting a chamber in a Handi Rifle project. Using a new unfired round I cut the chamber so that I had about .0005 below flush with the breach of the barrel, rifle closed and locked up great, the ammo performed well and looked good after it was fired. I re-sized it using a new set of RCBS dies with them properly setup in a good Herters press. First time through I ended up with brass that was about .002 over flush, so I lapped the end of the die down to get it the same length as factory, didn't grind the shell holder because I use it for the 17 Remington I have. Now things fit just like factory, life is good. When loading I first tried 20gr of 2520 which fit fine, those loads shot very well, but I could tell the pressure was fairly low. Max load for 25 gr bulelts was listed as 20.5 gr with 25gr bullets and I was shooting 20's, so I then filled a case to the bottom of the neck and weighed 20.8gr of 2520. This sounded good, so I loaded up a batch, not compressed but 99.99% full. I still had the unfired piece of brass, so I ran it throught the die and tried loading it. I could only get 19gr of powder in it and that was to the top of the neck. Where does 1.8gr of capacity come from after they have been fired? Seems like a lot of gain, especially since the case chambers the same as a new one. Just a curious observation or did I just happen to use a very thick walled case for my control case? This chamber reamer is a piolted PTG and the chamber looks perfect. Larry

[larryinIA]

I have found this while loading bulk for an upcoming pd trip in my 17 r brass, even from the same lot, same bag of brass. I measure about every 5-7 drops, just to make sure, then I look the 50 i just loaded over to make sure. I always pull a few that look inconsistent off, to measure the charge again. They look different, but the charges are indeed the same.

Curious,

larry

[tuck2]

The five boxes, that is 100 ea 17 Fireball cases that I have, weighed 81.5 to 83.0 grains after the cases were preped and trimmed to 1.402 inches. The 81.5 grain cases would hold a bit more powder than the 83.0 grain cases. I reloaded Hornady 25 Gr HP bullets, 19.0 Gr(MAX) Benchmark powder in 20 ea Rem cases with Federal 205M primers . The ft/sec velocity of the 25 Gr bullet at eight feet from the muzzle was 3,880. The 20 cases I reloaded weighed between 81.5 to 82.0 grains. The same fire formed cases were then neck sized and reloaded with 19.0 Gr of powder. There was very little difference in the powder leval in the case necks. Sixety of the cases weighed 82.1 to 82.4 grains and the heavest group of 20 ea weighed 82.5 to 83.0 grains. In any of my rifles the fire formed cases will hold more powder than a new or full sized case. Powder capacity will varry some what between the heavy cases and ones that weigh less.