Dealing with tight headspace

[st1650]

So I just received my Defiance anTI and I already had imported a prefit shouldered 300BLK barrel.

I'm still waiting for my go/nogo headspace gauge but it clearly seems like the headspace is tight just based off some rounds I already have on hand being very hard to chamber (no issues on my factory SPS) for example if I add 1 piece of tape or if the primer wasn't all the way inside the case. So without having to send it over to a smith, what are the possible issues ? I don't plan to use any factory ammo, could I not just bump the shoulder back a little? I am using new factory brass.
I planned to use it for long range subsonic so I don't expect to run really hot loads (ie under 40K psi). Also no issues with rounds loaded really long so it's not like its short chambered. I am just overthinking it ?

 

[Ledzep]

If you reload you can set the case headspace with the FL die. What's most important is the relationship between the case and chamber and you can set the case where you want it. Factory stuff will always be tight but if you're reloading anyway it doesn't matter.

 

[Dolomite_Supafly]

If you are making your own brass some will not work because the case is too thick resulting in a neck to thick to chamber.

Here is a good list.

STICKY - Good/Bad brass list converting 5.56->300blk » 300BlkTalk

BTW, I have done A LOT with 300 Blackout. Designed a bullet specifically for it then licensed that. I have helped a lot of people with the caliber.

 

[st1650]

If you are making your own brass some will not work because the case is too thick resulting in a neck to thick to chamber.

Here is a good list.

STICKY - Good/Bad brass list converting 5.56->300blk » 300BlkTalk

BTW, I have done A LOT with 300 Blackout. Designed a bullet specifically for it then licensed that. I have helped a lot of people with the caliber.

I don't do the 556 conversion since like 10 years ago, never had great success.
Now I have a couple of K of new factory made 300blk brass from a Canadian manufacturer. If I add 1/4 turn to my Forster 300blk FL die and resize my new brass and my primers are properly seated it feeds great no problem.

 

[Supersubes]

You’re saying that a round with a piece of tape on it is hard to chamber? How is it without the tape?

 

[spife7980]

You’ll be fine just screwing the die down the little bit. I’d get some calipers and comparators out to measure and control exactly where it goes smoothly instead of just going a blind 1/4 turn but I don’t think it’ll give you issues.

 

[Rubicon Precision]

Brass is not a gauge. Wait for your gauges before doing anything.

 

[whatsupdoc]

Are you checking with NEW brass or resized cases?