tight neck

[RWBlue]

Well after forming, trimming ....some 5.56 brass into 300-221 brass, I made some dummy cartridges.

I dropped them in the mag, I release the bolt, I try to extract, I try to extract, I TRY TO EXTRACT, I extract

What do you think, is stiff extraction of dummy round telling me that I can not use formed brass from 5.56?

Am I stuck with 221 Fireball brass?

Do I need to case my chamber?

[too_many_hobbies]

Also reference my other post you responded to...

I was also having trouble extracting unfired cartridges from my chamber. Using brass from the same lot, they extract properly now that I used my dies to set the shoulder back an additional .002". I have since talked to Redding and was advised to set the shoulder back even farther for my AR-15 gas operated weapon. They said that the .002" specification listed in the instructions with the dies is for a bolt gun.

[sniperx]

Use a sharpie to cover the bullet and chamber it to see where it is hanging at.
I found that the freebore area was close to the bullet dia. and had to seat the bullet in further (shorter OAL) to get them to extract. I just got another barrel and the loads I had made for the other one are sticking in the new one Good thing is I shot most of them yesterday , so I can start from scratch.

[pug]

RWBlue there is generally around .002" brass springback with a fired case so if you don't actually measure your chamber neck it should be about .002" larger than a fired case from a supersonic load. Subsonics don't always seal the case mouth so not a good test. I have measured brass and actual chamber necks from two popular 300/221 offerings and have the following data if you can make use of it.

300 Fireball chamber:
.338" neck dia.
.336" approx. fired case neck dia.

300/221 chamber:
.335" neck dia.
.333" approx. fired case neck dia.

The latter chamber will cause a press fit neck with some .223 brass and should not be fired especially with a supersonic load. You can turn the neck down and then load a supersonic round and fire it to get an idea. Tight necks are bad but close necks are good as far as accuracy goes. You want the neck to open up just enough to release tension on the bullet before it presses against the chamber wall. The neck will then guide the bullet into the throat straight but not hinder it and cause pressure to rise. I understand there is some factory .223 brass that loads to the correct neck size without turning (300/221) and it may be Remington but I don't have any on hand to measure. So far the military brass has had to be turned for the 300/221.

There is another thing you may run into as far as pressure levels rising and cases not extracting easily. Another dimension the reamer designers alter is the leade and throat. Just because brand A can shoot a 1800 fps 180gr load and extract easily doesn't mean brand B can. For example a 16" 300 Fireball can shoot 180s over 1800 fps and pressure is ok and cyles without a problem but yet a 10" 300/221 blows primers with the same load and the case must be pried out. Lengthen the throat on that 300/221 just a little and pressure drops just where it is suppose to be. So you see barrel maker A can chamber in 300/221 and not throat the barrel any deeper and barrel maker B can use the exact same reamer but use a hand throater to go a little deeper and the barrels will shoot nothing alike. Lots of variables with a wildcat.

[pug]

Actually really read your post again and realized you probably haven't shot any 223 made brass yet. If you have any 221 fireball made cases shoot a supersonic load and measure the neck on that.

[RWBlue]

I was able to fire 1 round of 300-221 that used fireball brass.

I have a tight neck. In fact I would say I have a very tight neck. I thought about measuring the outside diameter, but instead made a dummy round out of the used case. I didn't resize, I just squeezed a bullet into the brass. The outside now measures the same as the new ammo from Reedsammo.com 300-221 ammo.

Based on these finding, I don't see a need to use 5.56 brass.

I think buying a pile of fireball brass is my only option.