Well, all is not well in "Happy Town" today. I took out my newly built .300 Fireball to sight it in and out of the 5 shots that I put thru it 4 had primers come out of the case.  I measured the neck of a loaded case vs a fired case and there's plenty of chamber room for the brass to expand and let the bullet go so that's not the problem.  I'm loading a 150gr FMJ over 17.5grs of H-110(data says 17.0-18.0grs) so that should be ok, using Remington 7 1/2 Brench Rest primers as per loading data. The only thing that I can think of is the cases. They're "once fired" Federal .223 brass that's resized to .300 Fireball. It seems like the primer pockets aren't holding the primers firm enough. I don't know if a different primer would help that out or if the primer pockets are just worn out(remember, the cases are suppose to be once fired). This is the 3rd. Model "1" Sales kit that I've put together and the other two worked fine, of course they were in 5.56mm.  Still, I don't think it's the gun, I think it's something to do with the brass. What do ya'll think?

try any factory ammo?

Quoted: try any factory ammo?

NO, factory ammo is hard to come by. Only Cor-Bon makes it and it's very expensive.  I may have to break down and buy a box or two just to see but I really don't think it's the gun.  I'm going to wait and see what responses I get from the guy that I bought the brass from. He said he never has had a problem with it but then maybe he's using a different primer or load.  Just thought I'd throw this out there and see if anyone else had similar problems.  
Also, another thing I can do is order some .221 Fireball brass and resize it and load up some ammo to test. That would give me new brass with new primer pockets to test.  One way or the other, I'll work it out. Keep the replies coming. If any site on the web can help me fix this ARFCOM can.

Did some "google searching" and think that my load may be too hot. Could have something to do with the brass bing used or the ctg. OAL but I'm going to get a bullet puller from Midway U.S.A. and pull the 400 rnds. that I have loaded up. Also, I'm going to get another Lb. of powder and load some rounds up with a 16gr. load to see if it makes a difference or not.  If it does then I'll know that it was the load, if not then I'll know that it's the brass. I'm also going to get 100 .221 Fireball cases and give them a try, starting with the 16gr. load, of course.  I'll figure it out, heck, that's one of the "fun" things about firearms, getting them to work.  

BTT for the night shift.

Check this thread for some interesting info about federal brass.  

www.ar15.com/forums/topic.html?b=3&f=16&t=171144

From others experience it is not suitable for reloads, especially for a big neck resizing like with the .300.  I had the same problem with primers in some of my hotter reloads in .223.  I hope you haven't resized too many of those federal cases.

I bought them already sized from .223 to .300FB.  I'm going to get 100 rnds. of Remington .221 FB brass and neck it up and give it a try just to see if there's any difference. Also, like I said, I'm going to try a lighter load.  I really want to get this gun working, I've got a lot tied up in it. I think it's just an ammo problem.  

Well, I loaded up some 150gr bullets over 10grs of Blue Dot(starting load) and the primers stayed in place but the case didn't cycle. Not enough "ooumph" so I'm going to bump the load up just a touch and see what happens.  This is proof positive that my first load is too hot and needs to be backed off a bit.  I'll send off for an RCBS bullet puller and collet to put into my press and pull the bullets so I won't damage them, that  way I can save the powder and bullets and re-use it in a lighter load.  Back to work, I think I'll bump the Blue Dot load up .5gr. to see how it works.  Talk to ya'll later.  

Well, 10.5grs and 11.0grs of BlueDot w/150gr. bullet showed no pressure signs but they also didn't have enough "oomph" to eject the empty case either. Max. on the loading table was 11.0grs for BlueDot w/150gr. bullet so I'm not going any higher. I'll wait for that Lb. of H-110 tonight and load up some 16.0gr loads and see how they work.  Talk to ya'll later.  

Model "1" Sales CAR Kit in .300 Fireball w/A2 Flash Hider, A3 Flattop, standard CAR tele stock on a Century Arms lower, YHM Folding Front sight/gas block,A.R.M.S #40A rear sight,Trijicon Reflex II w/12.9MOA Triangle, Tactical Advantage  X-180 Single point Sling Mount w/680 QRB sling, M4 Handguards w/rail mount and vert. foregrip, A2 pistol grip modified to A1 specs. Here are some completed pics. Enjoy.  






This last one is a pic of a 5.56x45mm, .300 Fireball and a 7.62x39mm for comparison.

BTT for the night shift.

I think I've got it. I started with 16.0grs of H-110 with the 150gr bullet.  No signs of over pressure but it didn't lock the action back. Bumped the charge to 16.5grs and got lock back with no signs of over pressure.  I'm going to play with this load for a while and see how it works. I want to run a few rounds over the Chrony and check Velocity, If I'm in the 1900fps+ range I'll be good to go, Looking for 1950fps and I'd be exstatic,LOL.  Now the fun can begin.

What's the thread pitch on that muzzle?

Quoted: What's the thread pitch on that muzzle?

Model 1 Sales told me it was 1/2x36tpi(same as for the 9mm?) so I couldn't get the Phantom that they had. I know that they have to make a Phantom for the 9mm, I'll just have to look for one at a later date.  I really don't think that I'll need much flash suppression beings that I'm only burning 16.5grs of powder in a 16" barrel, the A2 should work ok.  
 I'm going to load up 150 rounds with the 16.5gr charge of H-110 since it seems to work ok.