300 BLK reloads and new build

[belizejet]

38453
The bottom one is my first build. It's in 300 BLK. It's almost done, however my reloads are not chambering. The factory ammo cycles though. I've taken a micrometer to the case dimensions and they are at the same measurements as the factory Remington ammo. I guess I should really say that they won't eject. They chamber but when I try and charge it for the next one they get stuck. Any hints or tips. The only difference is the profile of the projectiles are different. I have not gotten to the range yet with it.

spikes lower
FN 1/8 16" barrel
RRA lower parts kit and national match trigger
samson evolution rail

Just a few of my splurges.

[Hoser]

38453
The bottom one is my first build. It's in 300 BLK. It's almost done, however my reloads are not chambering. The factory ammo cycles though. I've taken a micrometer to the case dimensions and they are at the same measurements as the factory Remington ammo. I guess I should really say that they won't eject. They chamber but when I try and charge it for the next one they get stuck. Any hints or tips. The only difference is the profile of the projectiles are different. I have not gotten to the range yet with it.

spikes lower
FN 1/8 16" barrel
RRA lower parts kit and national match trigger
samson evolution rail

Just a few of my splurges.

What powder/bullet/velocity/ect?

[KS63]

Info on the projectiles.

[AKA-Spook]

38453
The bottom one is my first build. It's in 300 BLK. It's almost done, however my reloads are not chambering. The factory ammo cycles though. I've taken a micrometer to the case dimensions and they are at the same measurements as the factory Remington ammo. I guess I should really say that they won't eject. They chamber but when I try and charge it for the next one they get stuck. Any hints or tips. The only difference is the profile of the projectiles are different. I have not gotten to the range yet with it.

spikes lower
FN 1/8 16" barrel
RRA lower parts kit and national match trigger
samson evolution rail

Just a few of my splurges.

....seat a bullet deeper in .010 increments up to .050 and see if that frees them up. If you've gone past .030 I'd start to worry. Remember, as case volume decreases , pressure increases in case you're loading up to the edge.

[belizejet]

"....seat a bullet deeper in .010 increments up to .050 and see if that frees them up. If you've gone past .030 I'd start to worry. Remember, as case volume decreases , pressure increases in case you're loading up to the edge."

Thats what I was going to try. I've loaded them a little light with 18.9 grn H110. I've loaded nosler ballistic tip 125 grain and some 110 grn Amax. Don't have exact recipe with me. I noticed the shape of the bullet is causing it to scrape in the chamber. It doesn't taper down as fast as the factory ammo. If I seat it a little deeper I might avoid that.

[KS63]

Who's factory ammo?

[belizejet]

Remington

[KS63]

I've used the Nosler 125gr BT projectiles with zero problems. Nosler does have reloading data on the Blackout. I reload COAL are a little longer than what they tested at. No problems. Try using a Shapie and mark the bullet ogive and the case. Drop the cartridge in the chamber by hand and close the bolt. The marks on the bullet and brass may give you an idea of where a problem exists.

[20X11]

What is the trim length of your cases?

[legaleagle]

Had a similar problem with colt defender - 45 acp. Factory rounds worked perfectly, however reloaded with full length resize would not chamber all the way. When inserted by hand in barrel after dissaembly, it was noticed that some would sit flush with barrel hood, others would be about 3/32 from chambering. I noticed profile of bullets was slightly different and at recommended OAL I would get a ring on bullet after spinning it in chamber because it was resting against the rifling - bullet was fatter toward tip than other factory rounds. I sat bullets .020 deeper and reduced powder charge due to smaller internal volumes and increased pressures. This helped problem, but did not solve. Back to square one, I went through entire loading procedure and noticed that my crimp dies was not crimping as I thought. I reset and ran rounds through that were not chambering and whoala, everything fixed. Then I loaded to recommended OAL and crimped, with no problem in loading. I understand the 45acp head spaces off the case, not the bottle neck shoulder. However, without the crimp at .002, there was just enough flare on the case to make things tight. Not sure if this will help you, but thought I would share experience. You may also double check your case length. If you trim prior to resizing, the resizing will add some length to the case as the o.d. diminishes the length increases - I have seen as much as .006 on rifle cases.

[belizejet]

1.363 to 1.367. I read max was 1.368 and may be trying to save more brass. I'm going to trim the brass all to 1.363 and seat the bullets just a bit deeper and see what happens. Luckily I only made a few to test. I have 150 pieces of brass prepped so ill re measure and trim it all to trim length.

[20X11]

I had a CMMG barrel that had issues with brass longer than 1.363. I ended up trimming to 1.358 and the problem went away. The barrel had a tight chamber and I would get pressure signs even with factory ammo. I had a few reloads at 1.363 and longer than I had to "mortar" out of the chamber.

[belizejet]

Thanks. I think that may be my problem. I need to trim the brass more.

[Hoser]

That is exactly why I trim all the 300 brass I make to 1.355. Fits in all chambers.

The original 300 Whisper had a case max length of 1.400 and a trim of 1.395.

[legaleagle]

The other item of consideration is the wall thickness on the newly formed bottleneck. If the brass is too thick it might appear as if you have a tight chamber, when in reality your case is too wide at the bottleneck. This could be a fairly small amount - couple of thousandths. In check wall thickness you may all find a lack of concentricity, where there are thick spots and ok spots. As for max length, most manuals I have read indicate this to be a max by .010", thus trimming to 1.358 (based on max of 1.368) should be acceptable. To remove extraneous variables you may also want to trim after resizing and forming as the case in resizing appears to stretch as it becomes narrower in the resize. Good luck.

[belizejet]

Update: I trimmed the brass (all to less than 1.363) and loaded a bunch more up. I seated the bullets a few thousandths deeper also. Ran a lot better. Now the 130grn and lighter reloads run great. The 155grFMJ factory ammo is giving trouble. It won't cycle. Any suggestions?

[ray1970]

I'm assuming you have a carbine length gas system and are running the rifle without a suppressor? If so, my experience is that getting the rifle to cycle reliably once you start getting into the heavier bullets is difficult. That's one reason I took a break from the caliber. My next one is going to have a pistol length gas system.

[belizejet]

I was going to go with the pistol length gas tube but I read something that turned me against it. It basically said you would then have trouble with the supersonic ammo. It seems that no matter what you do you will have to compromise with the 300BLK. I originally built mine as a hog gun with the future plan of getting a suppressor. I might build another upper with SBR and Suppressor in mind with a pistol length gas tube. I like the fact that I can drive a 110 grn projectile at almost 2400fps out of an AR style platform now. Still more power than the 5.56 has. I still have to try some heavy subsonic loads. They may work better than the mid range loads that really have little purpose anyway since you cant suppress them but dont have the velocity for longer range. Im going to keep working with it and possibly do a three gun match with it if I can get it reliable enough.

[XC700116]

I was going to go with the pistol length gas tube but I read something that turned me against it. It basically said you would then have trouble with the supersonic ammo. It seems that no matter what you do you will have to compromise with the 300BLK. I originally built mine as a hog gun with the future plan of getting a suppressor. I might build another upper with SBR and Suppressor in mind with a pistol length gas tube. I like the fact that I can drive a 110 grn projectile at almost 2400fps out of an AR style platform now. Still more power than the 5.56 has. I still have to try some heavy subsonic loads. They may work better than the mid range loads that really have little purpose anyway since you cant suppress them but dont have the velocity for longer range. Im going to keep working with it and possibly do a three gun match with it if I can get it reliable enough.

Nope, just run a pistol length with an adjustable gas block. It'll run like a champ with any load you want to run in it. Yes you may need to tweak the adjustment screw from time to time when going from subs to hot supers but it works with all flavors. Been VERY happy with mine so far. 2 powders that will help with these issues are as follows.

AA 5744 for mid-heavy supers (125-155's) the stuff works great and produces more speed than any of the others I've tested (lil gun, H110, ect)

AA 1680 for Subs, produces really consistent subs and enough gas to run the action pretty well.

[belizejet]

Good to know. I've been looking for AA1680 but any find any. Anyone want to trade for some?

[belizejet]

Can't

[jerrymrc]

Good to know. I've been looking for AA1680 but any find any. Anyone want to trade for some?

PM sent. [Flower]

[20X11]

Dads Wholesale had plenty of 1680 at the last Tanner show. Another show this weekend. Also found 1680 at Cabelas Lone Tree a couple of weeks ago.

[belizejet]

I work weekends so I have not been to a gun show in over a year. From what I've heard the gouging is rampant anyway. I'll keep my eyes peeled for it at Cabela's. Thanks.

[XC700116]

Good to know. I've been looking for AA1680 but any find any. Anyone want to trade for some?

I would but I only have about enough to load up the 208 A-maxes I recently picked up into subs.

[jerrymrc]

I think I have him taken care of for the 1680 but since I used to load a bunch of 7.62X39 those out there might want to think about this. W680 was winchester's powder for loading X39 and discontinued. WC-680 was the LC powder used to load X39 and AA1680 is the current available X39 powder. All are right there burn wise.

My X39 loads use all three interchangeably. So if you come across some old reloader that has a few cans of W680 for $5 a lb it is nice to know what it is. Same with WC-680. Just a couple of years ago it was $80 for an 8lb jug. One still needs to work up loads but I guess I need to load some 220's with all three and run them across the crono and report.[Flower]