I know that not enough powder and hard to ignite powder will cause hangfires. But what is the cause of it????
Will adding a filler help stop hangfires?????

Won't hurt, but won't cure all cases of hangfires. Sometimes the primer can be defective and not produce the required amount of flame. Partially clogged flashholes or insufficient sized flashholes can do it. Old powder that is breaking down will cause hangfires. Even slightly less than normal firing pin hits on a primer, or a primer with a tougher cup metal will do it.

The one thing you never want to do is be too quick to open the action on a "dud" cartridge, as you never quite know how long it takes for a hangfire to finally fire.

Might want to describe your problem so's everyone can jump in with their pet theory and let you sort the wheat from the chaff, so to speak!

I've been working up some loads with AA2230c powder for a M1 Garand, 150j bullets. I've checked the burn rate chart and it's slower than 3031, so I sould be ok in the Garand.
At 46.0g I sometimes get a slight hangfire. You hear/feel the hammer hit, then the round goes off.
I've tried loads all the way down to 42.0 with hangfires happening more offten. Load book list 42.0 to 49.4 as safe.
All loads shooting 1" to 2" at 50yds.
AA2230c is a fine ball powder. Could it be to fine and be pluging up the primer hole???? Never heard of this being a problem.
My thinking is it's position sensitive. That's why I'm thinking of a filler. Dacron. But with the powder being so fine, will it get stuck in the Dacron and make things worse????
Reason I'm using AA2230c is I have a #8 jug. Wish it was IMR4895!!!!

I checked the Accurate Arms loading manual under the section for NRA High-Power. In the .30-06, for loads to match the correct M2 military loading, they recommend 44.5 to 49.4 grains of 2230. Now, they also say that the newer 2230C is a tad slower than 2230, but that you can use 2230 DATA as a starting point.

That said, I think your 46.0 load is perhaps a bit too mild. Go up two full grains and see if the hangfire goes away. I'm also suspecting powder positioning, specifically that the powder is being pushed away from the primer rather than being lit by it. Increased loading density will cure that, but I do NOT recommend any type of filler as a substitute for more powder. The problems you note are but the start of bad things that could result.

I think your load will come together between 48 and 50 grains of 2230C.

I loaded up some with 47.0 and 48.0 and will try them in a few days. Will post after I try it.

47.0 was good with only one very slight hang fire. 48.0 had no hang fires. Both loads were accurate to 100 yds. I guess 48.0 is the one.

I suspect powder or primer quality. That can only by getting new. Something ain't right and that could end up being dangerous. Proceed with caution. Let us know how it goes.

I think you're on the right track and I don't mean to switch you to a siding. But semi-autos have conditions that also promote hangfires. If the bolt isn't fully locking, or the cartridges are a bit short in headspace, then the firing pin fall can be partially blocked or absorbed. Slightly worse and you'd be getting misfires. Slightly better and the gun and ammo work as designed. You could have a speck of hard grit in the bolt locking mortise, a bit of primer metal or hardened grease inside the bolt, bent actuating rod or several other very minor problems. Or your ammo may have the shoulder set back a few thousandths too much - or too little. Either can cause a hangfire.

But again, I don't want to drive you to distraction. Just pointing out that there MIGHT be other areas to explore in troubleshooting mode.

The primers look to be getting a good hit. Dents are deep. They are PMC primers. Was cheap.
Powder is about 4 years old. AA 2230c surplus. Never used this powder before. Was cheap.
All shells full length sized and trimed. Primer pockets trimed. All Winchester brass.
Same primer, with a cast bullet experiment, same rifle, H4895, no hang fires.
Could it be the powder????
I'll try the same rounds in a bolt action and see what happens.
Never had a powder go bad on me. Always a first time.

The primer pockets must be of correct depth, and the primers must be deated to the bottoms of the pockets. Otherwise, some of the firing pin's energy is absorbed in seating the primer, and may not ignite the compound properly. Learned that the hard way…

I used the RCBS primer pocket uniformer. All are the same depth and even all the way down. Great tool.

Ballistically, 48 grains of 2230 under a 150 grain match bullet gives OK muzzle pressure. To get the same 8200 PSI of muzzle pressure that M72 Match gives, you would need to go up to 50 grains. At 42 grains the powder only used 67% of the case capacity. That is extremely low. Shooters of M72 used to complain becaus the 46.5 grain charge of 4895 only fills the case 84% full, and that meant an 80 foot per second spread between a shot fired after tipping the gun up (powder to the rear) and a shot fired after tipping the gun down (powder to the front). Primers would go from fairly flat in the first case to pretty round-edged in the latter. And this is an easy-to-light stick powder.

A tough-to-light ball powder will get into even more difficulty. Even at 50 grains, however, you are still only filling about 79% of the case powder capacity. That's still a pretty low number. Moreover, I've had the experience with 2520 in the .308 that my groups shrank from 1.25" at 100 yards to 0.75" just from deburring the flashholes. That step made no difference with any stick powder I tried, but boy, the ball powder should did light up better that way. Moreover, the CCI 34 primers made for military guns are magnum primers, specifically because they are geared toward ball powder ignition.

So, if you must use that powder, get magnum primers. Deburr your flashholes inside the case (the tools are cheap). Work your load up over again from 42 grains with this hotter ignition system. When working the load up and watching for pressure signs, tilt the gun up in the air before each shot to settle the powder back over the flashhole, then slowly level it down onto the bags. This way you are watching for pressure in the worst case. When you have your load from that work, I expect your non-tilted rounds will be lighting much better as well.

Nick