Switching brass 300wm fc17>norma

[Wide Glide]

I stupidly did load work up using FC 17 brass knowing some of the primer Pockets were loose before I started. I was planning to just keep buying more brass thinking I would get at least three to five firings from each piece but at this rate they aren't even worth picking up. Before coming to this conclusion I worked up two loads that I am extremely happy with. Once I was finally done kicking myself I ordered a few hundred pieces of ABM headstamp brass which is said to be made by Norma to Norma's normal specs but with the ABM headstamp for them to use for factory ammo.

Rather than starting the whole load work up from the bottom again I was hoping maybe someone made the same switch and could give me an idea how many grains less to expect to use to get to the same velocity. Usually I would just start a grain or so lower but I am also usually loading smaller calibers. Since I am loading for 300 Win Mag and My Chosen loads are already on the hot side I figured I would ask first. As soon as I got back from the range with the first batch of testers in federal brass the first thing I told my buddy was that the only thing I could find about this rifle that I didn't like was that it was going to tempt me to push the limits because it is the first rifle I've ever owned that seem to shoot better and better the hotter you loaded it, most of my other rifles seem like the best accuracy came from way below book maximum.

Current chosen loads
208gr eldm
Fc17 brass 248/249gr
Cci Mlr
3.6 col
0.025" jump
77.0 gr h1000
2913 fps


225gr eldm
Fc17 brass 248/249gr
Cci Mlr
3.65 col
0.025" jump
76.0 gr h1000
2855fps

Both loads show slight cratering at 92 degrees 700 foot elevation in Pennsylvania. It is very rare that I shoot in any temperature hotter than that.

Any idea where I may want to start to get the same results with the new brass? I'd rather not have to start at seventy-three grains again and load 10 of each in half grain increments the whole way up

 

[Wolf76]

no direct experience here, but given abm / Norma case capacity is near the top for the 300 - I'd start maybe 1-1.5 grains under for safety sake. you only need to match velocity to keep your groups.

 

[bpcrshooter]

you could check grains of water for both cases, see how much they differ. if not by much, I would still start a little low, bullets are cheap!!

 

[MagnumManiac]

If you're primer pockets are getting loose after 2-3 firings...reduce the powder charge for gods sake.
It is a well known fact that Norma brass is thin in the web, this is why primer pockets expand so easily. Winchester brass is very thick in the web, often more than DOUBLE the thickness of Norma brass, hence why it is often regarded as hard, but in reality it is the thickness of the web that governs how well primer pockets hold up.

Cheers.

 

[Wide Glide]

If you're primer pockets are getting loose after 2-3 firings...reduce the powder charge for gods sake.
It is a well known fact that Norma brass is thin in the web, this is why primer pockets expand so easily. Winchester brass is very thick in the web, often more than DOUBLE the thickness of Norma brass, hence why it is often regarded as hard, but in reality it is the thickness of the web that governs how well primer pockets hold up.

Cheers.

try reading my first post again without skipping the first paragraph lol

As I said in the first post the loose primer pockets were in the FC 17 Military brass.... I also said in the first post that they were like that before I even started..... I did not say I was getting loose primer Pockets after 2 to 3 firings I haven't fired a single one of them more than once.

 

[livetohunt]

my FC brass lasted 6-7 firings with no annealing on a 300 win mag.

 

[bullet man]

I know when I deprime factory brass that has primer sealant on them they are a little bit more difficult to get out. I got some brass that had some loose pockets so I'm sealing them up let you know if that helps. After firing them they will go in the scrap pile

 

[Wide Glide]

Tonight will be a long night of measuring and brainstorming. Right after posting this thread I hit the bench and started loading new test batches starting at 75 grains and just made it out to test them today. I only ended up shooting 1 group because this new brass were showing pressure signs at 75 grains that were equal to what I was seeing at 77.5 in the fc brass. That seems to be a little extreme to me and has me puzzled because I used all the same components and only changed brass. The only thing I can think of is that FC brass was extremely oversize when I got it and I only sized it enough that it would chamber smoothly, meanwhile the ABM brass was brand new and probably sized to minimum dimensions. I'll dig into it later tonight and see what I can figure out but I'm probably going to wait until the new dies come to reload another batch. I recently got sick of struggling trying to milk every bit of accuracy I could out of some of my gear that should have been replaced a long time ago.

On the plus side even though I only shot one group because I was afraid to step up to the next charge the one I did shoot wasn't half bad

 

[Wide Glide]

Using my hornady comparator setup to measure shoulder

Unfired 2.251 average
Fired. 2.273 average

Seems kind of extreme...

 

[Wide Glide]

I probably should have just bought more fc brass. The abm brass is 30gr lighter (219 vs 249) than fc, shows pressure signs 2 grains sooner, started finding loose primer pockets on second firing.

I thought i was upgrading but apparently not. The accuracy node was a mile wide with the fc brass and impossible to miss, yet i cant seem to get under an inch to save my life with the abm.

 

[Wide Glide]

This ABM brass start showing pressure signs way sooner than the FC brass even though they seem to average about the same velocity per given charge weight as in 76 grains of h1000 will give me about the same velocity in either case but while the FC brass looks fine the ABM brass is screaming for help with flattened primers and very shiny very distinct ejector marks. By the time I dial back the ABM brass loads enough that they look even remotely safe I'm giving up over a hundred feet per second which takes me completely out of the higher wider accuracy node and puts me down into the lower node that is a lot more narrow at this point the only positive I can see to using this brass is it may offer more case life but I won't have any idea until I shoot at a few more times I am only on the second firing. We will see how well the primer pockets held when I go to seat primers for the third loading. At this point though I am considering trying another type of brass or just stocking up on the FC brass and expecting to throw it away after two to three firings