.300 Blackout; Anyone tried CFE BLK?

[Rich@CCC]

This thing is going to drive me nuts!

I checked the lead on my chamber and I am far short of the ogive contacting the rifling.

I loaded up several different charges and hit the range today. The original seven rounds from the first loading all chambered, fired, and cycled fine. The rest did not go so well. Out of 15 rounds, 4 chambered and fired. I did not try to force them this time. I just came back to the shop and measured them. Every one of them measured below SAAMI(as listed in Lyman's 50th) spec in all dimensions except distance from base to shoulder and all of those were dead on spec. I then loaded all the rounds that would not chamber at the range into the same magazine I used at the range and every one of them chambered and went into battery by dropping the locked bolt with the bolt catch/release.

I'm going to have to pick up a chamber gauge, unless one of you fine gentlemen have one you'd be willing to loan out. I'd pay shipping obviously.

I will get a case gauge. I don't believe for a second that any of these would not drop right in, unless the printed spec. in the Lyman manual is wrong. The Lyman data matches what I could find on the interwebz from SAAMI +/- .0001".

[Rich@CCC]

BTW, Just to be clear, I am using a Lee Precision full length resizing die to form these cases. I could not find a true forming die anywhere. I may go ahead and buy an RCBS small base resizer and give that a shot. I hear they are closer to the bottom end of spec than Lee.

[Odin Bravo One]

Rich, it's hard to diagnose without seeing the components and rifle. At least for me. I'm a visual dude. If you're attending the TLG Memorial shoot, I'll happily bring my tools, gauges, and what not to take a look. Could also be that aspects of your load are just not agreeable with your rifle/pistol....... and/or vice versa. Knowing we all try to build as cheap as we are comfortable with, and having been in the BLK game for awhile now, I can say I've seen a lot of variation in parts and components for both guns and handloads. It only takes one item to be FUBAR to throw everything off.

FWIW, I've had issues with Pmags of various Generations functioning even my factory loads. I have a surplus of HK mags from back when they were free and they are very forgiving of the COAL and functioning in my rifles. BLK specific Mag bodies and followers have helped more than a few people with feeding issues.

Still, I'm afraid without being able to see and measure all elements in the equation, I'm afraid you're gonna be stuck playing detective one item at a time until the culprit is found. If you change more than one thing at a time, you'll never find out WTF is going on with your set up.

[Mike C]

Rich, it's hard to diagnose without seeing the components and rifle. At least for me. I'm a visual dude. If you're attending the TLG Memorial shoot, I'll happily bring my tools, gauges, and what not to take a look. Could also be that aspects of your load are just not agreeable with your rifle/pistol....... and/or vice versa. Knowing we all try to build as cheap as we are comfortable with, and having been in the BLK game for awhile now, I can say I've seen a lot of variation in parts and components for both guns and handloads. It only takes one item to be FUBAR to throw everything off.

FWIW, I've had issues with Pmags of various Generations functioning even my factory loads. I have a surplus of HK mags from back when they were free and they are very forgiving of the COAL and functioning in my rifles. BLK specific Mag bodies and followers have helped more than a few people with feeding issues.

Still, I'm afraid without being able to see and measure all elements in the equation, I'm afraid you're gonna be stuck playing detective one item at a time until the culprit is found. If you change more than one thing at a time, you'll never find out WTF is going on with your set up.

Not to thread drift but if ever you had the time Sean M it would be epic to see a thread with some of your general notes, thoughts and observations in running/maintaining a 300BLK carbine. It would be good even if it was just a short list of what components are optimal or sub optimal based on your observations and experience.

[GuanoLoco]

This thing is going to drive me nuts!

I checked the lead on my chamber and I am far short of the ogive contacting the rifling.

I loaded up several different charges and hit the range today. The original seven rounds from the first loading all chambered, fired, and cycled fine. The rest did not go so well. Out of 15 rounds, 4 chambered and fired. I did not try to force them this time. I just came back to the shop and measured them. Every one of them measured below SAAMI(as listed in Lyman's 50th) spec in all dimensions except distance from base to shoulder and all of those were dead on spec. I then loaded all the rounds that would not chamber at the range into the same magazine I used at the range and every one of them chambered and went into battery by dropping the locked bolt with the bolt catch/release.

I'm going to have to pick up a chamber gauge, unless one of you fine gentlemen have one you'd be willing to loan out. I'd pay shipping obviously.

I will get a case gauge. I don't believe for a second that any of these would not drop right in, unless the printed spec. in the Lyman manual is wrong. The Lyman data matches what I could find on the interwebz from SAAMI +/- .0001".

You don't want just any case gauge - you specifically want the Sheridan slotted for this.

SAAMI spec is fine and good but your chamber is what it is - and I have seen significant variation in my sample size of 2. Try seating the bullet deeper.

[Rich@CCC]

Sean,
I'll bring the pistol to VA next week. I wasn't going to ask, but I sure do appreciate your help on this.

GuanoLoco et al,
I picked up a box of Selier & Bellot sub sonic, 220gn cartridges today and they feed and chamber fine manually. But then so do my hand loads that refused to go into battery yesterday.

The diameter at the shoulder is about .003 greater on my hand loads than the S&B cases. SAAMI Spec is .361", mine measure .360" and the S&B cases measure .357". That is the only measurable difference I can detect. Other than COAL and mine are shorter with lighter bullets. My loads are .17" from contacting the lands.

If all I have to do is get a tighter sizing die for the initial form up, I'll be a happy camper.

GL,
Just out of curiosity, how would the Sheridan slotted gauge be any better than any other drop in gauge? It can't match my chamber specifically.

[Mike C]

BTW, Just to be clear, I am using a Lee Precision full length resizing die to form these cases. I could not find a true forming die anywhere. I may go ahead and buy an RCBS small base resizer and give that a shot. I hear they are closer to the bottom end of spec than Lee.

Rich, I think you might be onto something with the small base die. Not saying your barrel couldn't be out of spec because that isn't out of the realm of possibility but I do question surplus 5.56 cases converted to 300 BLK especially if they've been run through a 249. Out of curiosity did you source the brass from once fired from your own gun in 5.56 or is the brass converted from a CO using a surplus supplier? Additionally, have you tried resizing and reloading any factory once fired 300 BLK brass? Is the result the same? If you aren't contacting the rifling and you don't have a way to spec the chamber this might be an easy way to narrow down your problem without running out and buying a small base die or gage.

[Rich@CCC]

I'm using LC brass bought once fired and reloaded 2-3 times and run through my 5.56 ARs. I did not anneal the brass before reforming. I'll be adding annealment to the process as soon as I prove the concept.

[Mike C]

Blew my theory out of the water. With that I wouldn't waste my time with a SB die. I think your best bet is to have Sean M look at it. Please keep us apprised though as I am very interested in what the resolution is. All I run now is 300 BLK so any data points I can pick up on possible issues and resolutions would be very helpful. Thanks for starting the thread and sharing the info.

[Odin Bravo One]

Rich can you also be sure to bring all of your load and velocity data? My chamber and H/S gage are out in temp loan, but I've asked for them to be returned by next weekend. I'll also bring a handful of different factory and handloaded ammo so we have a smorgasbord to work with.