Strange 300Blk loading issue

[lwink]

Just started loading for this caliber, worked up a few basic 110 V-Max loads to try before pumping them out on the dillon and about 5 shots in (with promising accuracy) had a "click" no fire. Turns out my bolt didn't go all the way into battery so no bang, no big deal on a new gun. Had to take some serious measures to open the bolt (slide hammer action on a concrete pad).  Figured it had something to do with the load so I got home and started looking and here is the troubling issue - about 3-4 of the 15 loads I made are between 1/8 and a hair more not seating fully in the chamber, so a closed bolt just jams them on something and all is stuck. Was able to recreate this in slow motion and hand chambered all loads just to see.  Most worked fine in and out of chamber, some stuck and wouldn't go into battery.

It's a BA Hanson Barrel, faxon bolt that has been used extensively in other rigs with no issue. 

 

So here is what I tried:

1. All loads easily go into Wilson case gauge (checked this before and after "issue" with all rounds)  This is strange, none feel tighter or different than others in the gauge

2. All bullet seating (off ogive) is within a couple thousands and shouldn't be in the lands at all - also no marks on bullet after jamming in and pulling out

3. All trim lengths are within a few thousandths and within spec

4. Put non chambering rounds on concentricity gauge and runout is .004" max

5. Just for fun put calipers on shell base just above rim in case sizing wasn't complete, no real noticeable issues there, and think the wilson gauge should catch this anyway

 

My next thoughts -

1. Will try these in a friend's blackout rig and see if issue remains, could point to a tight or flawed chamber? Visual inspection of the chamber didn't lead to anything obvious. May give it a good scrub with JB and see if that makes a difference

2. Pull bullets and resize without decap pin and see if this allows brass to fit?

 

And most importantly - your thoughts or questions??

 

Thanks!

[Ben53]

If you're using mixed brass, the case neck thickness might be off.. not unknown to have a tight chamber there.  Have you measured overall neck diameter on both the cases that fit the rifle chamber and those that don't?  Just a thought.

[Tom Freeman]

If the ammo went in the gauge but not the chamber that means your gauge is not as tight as your chamber.

 

Most likely he didnt have the shoulder bumped back far enough.

 

The ammo that didnt work, check the headstamp.  Lots of non-US headstamp brass will produce 300 Whisper/Blackout necks that are too think.

[Boomstick303]

2 minutes ago, Tom Freeman said:

 Lots of non-US headstamp brass will produce 300 Whisper/Blackout necks that are too think.

 

In the little research I have done in creating 300 Blackout casing from 223 I have also read this a couple of times of non-US headstamps creating necks are too thick.  Maybe a rabbit hole to do down.  

[Guy Neill]

Four areas typically of concern include;

 

1. OAL - though you said they were not contacting the rifling.  You also said by only a couple of thousandths - general recommendation is about 0.020" off the rifling, assuming there are no problems fitting the magazine.

 

2.  As mentioned, the cartridge neck diameter.  Are the case reformed 223 or made as 300 BO?  Reformed cases in particular may see greater differences in the neck area.  Still, the gauge should indicate something.

 

3. As you looked, the sizing operation.  Small vase dies are sometimes needed for semi-autos

 

4.  Case shoulder.  If not set back a bit (0.003" or so) it can be a problem.  Once again though, the gauge should have revealed this.

 

It's likely the gauge will accept standard sizing while the chamber needs small base sizing.

[lwink]

Thanks for all the info, following back up with a few things I’ve learned. 
1. Not a head stamp issue, had some lake city that didn’t fit and some that did. 
2. measured neck thickness and couldn’t find a pattern there, but wouldn’t rule it out 

3. ended up running a Lee taper crimp and that actually allowed a few to chamber freely that didn’t before, but didn’t fix all of them
4. Had a couple “bad” ones that I pulled Bullets, resized, and will reload time see if they go in now. Empty brass freely chambers, although not sure if it did pre-loading. 
 

step 4 is probably the real test, if they work on the next load I Will just run all This brass through my cranked down sizing die before loading and all should be good. A bit of a bummer, but better than jamming The gun up all the time.
Too bad about the Wilson gauge, doesn’t do me much good at this point if it won’t gauge what I need, guess it’s an adequate trim gauge.  

[ltdmstr]

Just curious, but did you check the rifle with go/no go gages when it was built?

[Ming the Merciless]

The Wilson case gauge is not a chamber gauge.  It is more of a case length/shoulder location gauge and does not check for 'fat' cases.

 

https://www.midsouthshooterssupply.com/item/00088cg3acc/lpointepoint-wilson-cartridge-case-gage-300-acc-blackout

"This is a one-piece, non-adjustable cylinder-type gage for checking fired and resized cartridge cases for cone-to-head and overall length"

 

  Get a real chamber case gauge from EGW, or Lyman (which I think are made by EGW)

 

Take a sharpie and color the entire case and then after chambering it, look to see where the sharpie is rubbed off.

 

HA, found the post I was looking for

 

 

Edited October 23, 2020 by Ming the Merciless

[lwink]

On 10/21/2020 at 8:49 PM, ltdmstr said:

Just curious, but did you check the rifle with go/no go gages when it was built?

Yep, it’s all good there.

 

On 10/22/2020 at 8:57 PM, Ming the Merciless said:

The Wilson case gauge is not a chamber gauge.  It is more of a case length/shoulder location gauge and does not check for 'fat' cases.

 

https://www.midsouthshooterssupply.com/item/00088cg3acc/lpointepoint-wilson-cartridge-case-gage-300-acc-blackout

"This is a one-piece, non-adjustable cylinder-type gage for checking fired and resized cartridge cases for cone-to-head and overall length"

 

  Get a real chamber case gauge from EGW, or Lyman (which I think are made by EGW)

 

Take a sharpie and color the entire case and then after chambering it, look to see where the sharpie is rubbed off.

 

HA, found the post I was looking for

 

 

This is good to know, and lines up with my experience now. May consider running a different case gauge, although at this point I will just go through with sizing all my “ready to load” processed brass as that seems to eliminate the issues. Ran a bunch Friday after full resize with no issue and new Hornady brass has no issues so far. 
 

thanks for all the help, hopefully this post helps another loader down the road. 

[Farmer]

Late to the show here. 
One other issue I’ve seen with forming brass is that some will be thicker on one side of the neck. Usually starts to show up after a few reloading’s but you’ll start to notice a bulge on one side of the neck when the bullet is seated. The bulge is usually the thin side and can make chambering a problem. Generally just turning down the high/thicker side will gain a few more reloading’s. 

[NOSHMJ]

As odd as it sounds, have you tired a small base die for resizing?

[jtaylor996]

I recommend the sheridan engineering slotted 300BLK gauge. It will tell you everything you need to know, as well as if you ogive is good for the chamber.

 

However, I've been playing with an OAL gauge lately, and there's no way in hell any super bullet gets in the same zipcode as the rifling in this caliber when it fits in a case at all, much less mag length.

 

I bet you just need a small base size die.