Help me figure out this problem (.300-221 rechambered to .300 BLK)

[Greywolf]

I have a 16" .300-221 that has never run right.

It is a 1:8 twist with gas block in the pistol position, and has a High, Low, and Off setting on the block. My 8" gun with the same thing and made by the same manufacturer runs perfect.

The 16" for the longest time would fire, but the cases wouldn't eject. They'd get stuck, bad, and the rim would get ripped off partially (about 20% where the extractor claw tried to pull it out of the chamber). I'd have to use a cleaning rod to tap it out. If I just tried to hand load/eject I'd end up having to really pound the hell out of it to get it out.

I triple-checked all my dimensions on my reloads, and I was still having issues so I sent it back to the maker. He reamed it out to .300 AAC BLK, saying that this should fix the problem.

Well, took it out to the range today to test it. Some strange things are happening.

Before I sent the barrel off, it never had a problem chambering or firing. The problem was occurring when it came to ejecting (either by hand before firing just to see if it would eject, and it wouldn't, since the chamber was too tight) or after firing the case would get stuck and the rim would get ripped off.

Well, when I got the barrel back and put it back together I was hand chambering the cases and they wouldn't eject due to the bolt/extractor apparently not gripping it, but I thought that the gases and recoil would help this. The cases weren't getting stuck at all (they wold fall right out when I tilted the rifle back), and things seemed pretty slick there.

At the range I chambered a round and pulled the trigger - nothing happened. I ejected the round and saw not even a slight dimple in the primer. This is the same bolt/upper I used before that never had a problem getting a round to fire. I then swapped lowers (different triggers in each) - no dice. I then swapped bolts - again hardly a mark on the primer.

Is it possible that somehow now the chamber is too long and the bolt isn't engaging the back of the shell enough to allow not only extraction by hand (as previously written about) and also the firing pin even when fully extended isn't reaching the primer due to a chamber/size problem?


Here are my loads and dimensions:

Load 1: Nosler 125 grn Ballistic Tip, 18.5 grn H110, OAL 2.046", Case Length 1.360" - 1.363"

Load 2: 115 grn. FMJ, 16.5 grn H110, OAL 2.041", Case Length 1.360-1.363"

Is it possible that I cannot use this .300-221 ammo in my newly chambered .300 BLK, but that if I get BLK dies and load those up per spec I can then use the new ammo (as well as factory ammo) in the 16" upper? Would I be able to use my current .300-221 brass and just resize in the new dies?

 

[SharpsDressedMan]

See reply to your other post re: small base sizing.

 

[Greywolf]

My dies are small-base dies.

I just pulled some bullets, resized again, put primers in as far out as I could (being very careful not to push them in too firmly) and I am still not getting so much as a scratch or slight dimple on the brass. And of course I'm still not getting any extraction of the case by the bolt - I really feel like the chamber was reamed too far out.

Very odd.

Or, is it possible, that when I put the barrel nut back on that I didn't tighten it down all the way and so there is a gap?

 

[S. Hill]

It sounds to me like your chamber was cut too deep. If the barrel extension/nut wasn't tightened correctly, your gas port wouldn't line up (unless you were a full turn off)

Your safest option is to get a .300 AAC NO-GO gage to check your chamber. If it goes, your chamber was cut too deeply.

It is my understanding that the only difference between the .300-221 (whisper) and the .300 AAC is in the neck diameter and the throat. The shoulder should be in the same place. Headspacing on the shoulder, your .300-221 should work just fine.

RSilvers is the expert on this project, you should check with him.

 

[Greywolf]

I have an IM into RSilvers so hopefully he'll have some insight. It is so damn frustrating, since the maker is a well-known manufacturer and I've not read any negative stuff on other boards - the 8" upper that I had him do the barrel for works like a champ. This 16" has been nothing but problems, though. I finally was excited since I wasn't having to POGO the damn thing anymore to get a loaded round out, but now this problem arises - ugh. I'm so tempted to pitch the barrel and go with another caliber after all this.

 

[unwise11]

Are you trying to fire .300 Whisper in a .300 AAC rifle?
Otherwise it sounds like it was cut too deep, and as stated above a .300 AAC NO-GO guage would help.

 

[Greywolf]

Yes, trying to fire .300 Whisper in a newly rechambered .300 AAC barrel. Maker tells me it should work fine. I may have to get a NO-GO gauge.

However, I'm experimenting with something else right now that may cause me much embarassment if it turns out to be true - stay tuned!

 

[unwise11]

Thats really odd.. Fire .300 AAC in it, get some .300 AAC ammo and tell us how it works.

 

[Greywolf]

Well, color me embarassed. I think I figured it out and I feel like an idiot. It seems that my shoulder is set a little too far back. For some reason when I reloaded these rounds the dies (must have been the way I set them up) pushed the shoulder back too much.

So, a question - should I get a .300 AAC go and no-go gauge and perhaps also send my 8" barrel in for rechambering, so that way I'll be up to spec on both barrels? It is working fine, but I wonder if perhaps since all of the new factory ammo is going to be for the .300 AAC perhaps I should go that route with a rechamber on the 8". I assume I'll still be able to use my current ammo that is working fine in the 8" even after the rechamber, correct?

Also wondering if I should get the new .300 BLK dies, or if I can continue to use my current .300-221 Forster dies.

 

[rsilvers]

Forster doesn't have 300-221 dies. If you mean Redding, they are likely ok to use.