Small base dies?

[armoredman]

I test fired my new Trash Panda frankenAR the other day with my reloads, and almost all of them wouldn't go into battery fully. A second range trip with factory ammo only showed me it was definitely my reloads causing the issue. I had never experienced this before, and was told small base dies or an X die would solve the issue. The BREN 805 eats up everything I feed it with no problem whatsoever. But I HATE buying factory ammo if I don't have to....
Thoughts?

[steerclr]

Since it is a semi-auto rifle I assumed you completely resized the case and not just the neck as you would do with bolt action rifle.  Do you also use a case length gauge (a one-piece, non-adjustable cylinder-type gauge for checking fired and resized cartridge cases for cone-to-head and overall length and used to compare cartridges against the minimum and maximum SAAMI cartridge dimensions) to check each case?  I assume you did all of that so I am puzzled why the rounds didn't work.

Midway has a clearance on small base RCBS dies ($37.97) for the .223 and the description states this;

" With this combination reloading for an AR-style, semi-automatic, pump action or lever action rifle just became a lot easier. Small base sizing dies size brass to minimum specifications and help to ensure that cartridges will chamber every time. The taper crimp seating die is helpful as it is a bit more forgiving die for crimping cases that have variable case lengths; helping to reduce the number of bulges and buckled shoulders when crimping in bullets with a cannelure. Due to the fact that this product sizes more than regular dies, it is crucial to have a sufficient amount of high quality lubricant to prevent stuck cases"

I always learn something on this forum.

[M1A4ME]

If it requires small base dies (resizing die is what is different) what does that say about the rifle chamber/bolt combination?

Your current dies make ammo that works in your Bren with no issues.  Your dies aren't bad/wrong, the AR15 chamber is just very "tight".

I've said, before, I've built two over the years that had similar symptoms to yours.  My reloads work in 8 to 12 other AR15's perfect.  Suddenly I build one that won't chamber the reloads.  Dies?  Or rifle?

I know how I solved my issues and you don't have that option (grab a set of headspace gauges and swap bolts between AR15's to find a combo that results in slightly increased headspace.)

You only have the two .223 semi autos?  How much ammo (reloads) to you have waiting on range trips? 

Going to a small based resizing die might not be much of an issue for you.

One of the objections I've seen over and over (on the internet, of course) is that small based dies "overwork" the brass and result in decreased life of the brass.  However, I've never seen a study that shows that, but some people say it (on the internet.)

[dragon813gt]

One of the objections I've seen over and over (on the internet, of course) is that small based dies "overwork" the brass and result in decreased life of the brass.  However, I've never seen a study that shows that, but some people say it (on the internet.)

We?re talking 223/5.56 brass which is dirt cheap and plentiful.  At this point the surplus supply of brass isn?t drying up anytime soon.  So if you lose some cases earlier so be it.  The X die has the advantage of sizing to minimum dimensions and stopping case stretch.  If you want the round to chamber in every rifle and not trim after initially doing so then buy an X die.

[IDescribe]

... my reloads, and almost all of them wouldn't go into battery fully. A second range trip with factory ammo only showed me it was definitely my reloads causing the issue.

Thoughts?

A-man, trouble-shooting bottle-neck reloads for auto-loading rifles is not my area of expertise.  But with my own limited knowledge-base, the first thing I would do in this situation is ink up a cartridge, chamber it, and then examine the ink to make sure I knew exactly where the troublesome contact points were.

[IDescribe]

I'd also compare the dimensions of one of my resized cases to a case from the functional factory loads.  Just the case dimensions.  And see if something is well out of whack there.

[Moken]

I'd also compare the dimensions of one of my resized cases to a case from the functional factory loads.  Just the case dimensions.  And see if something is well out of whack there.

Bulls-eye!
I would rather have a chamber that can run most loads, in that caliber especially. I've ran my loads in 3 ARs a Tavor and Mini 14 with no problems and I watch my shoulder by only setting it back .003 from my Mini 14 chamber. I've also used RCBS and Lee dies.

[roadtrip]

Were you loading brass that may have been military machine gun ammo? If so, machine gun chambers are a bit loose and the cases expand more than usual. In that case a small base die will bring them back to ok. I know this is especially true of 7.62 MG brass.

[armoredman]

Well, the interesting thing was somehow, the problem seemed to be more the magazines dragging the bolt than the ammo itself. One we changed to a different mag, changed the disconnector, tweaked the gas block/tube, everything seemed to work just fine. I had one not go into battery using a MagPul Gen 2, then discovered they are specifically not recommended for this lower. Using the D&H tactical everything worked perfectly, and the one that wasn't "in" went in with no problem with the forward assist nudging it right along. It apparent is a known issue with this specific lower, being mag sensitive. The BREN will use anything but it's a purpose built milspec carbine, not a mixmaster Trash Panda.
BTW, this is actually the third 5.56mm rifle I've loaded for - the wife's dearly departed vz-58 5.56mm rifle also had no trouble with my reloads. However, a small base of X die might be a good thing to have anyway. This coming weekend I will experiment with more magazines and different loads. Even if it's a finicky as a real trash panda I am having fun with the whole thing.

[armoredman]

Problem did not go away, but lessened, to 6-8 out of 50. Unacceptable, of course. Most of the stuck ones had to be mortared out. I will say the LOAD is well accurate enough for me, but I need perfect functioning. Non magazine, issue, (I was wrong), and I bit the bullet...bought small base dies. We'll see from here.

[M1A4ME]

I have had receiver issues that showed up with magazines.

I had to remove some plastic from the top of right side feed lip on the Black Dog .22 magazines due to the bolt rubbing it and slowing the bolt down enough to keep it from fully chambering.

I have a non-AR15 .223 semi-auto that will only work with some magazines.  Some will not lock in, which I believe is due to the top of the magazines hitting the upper before the magazine catch is correctly lined up/latched into the slot in the side of the magazine.

It happens, some times parts just don't work well together.  I could be your lower is close, but not quite right.

I've really never gotten to the point where I felt the need to label/tag magazines with a number/letter so I could track problems, but a lot of people do that.

If it's a very tight chamber (diameter is on the small side/very close to minimum) the small base die should help.  If the chamber is a little short the SBD's may not completely fix it.  Please take the time to come back to this thread and let us know, I'm curious.

[armoredman]

i was VERY short on bullets so I am giving this a caution thumbs up - all 18 rounds loaded chambered and fired without issue. The only problem was the small base dies didn't seem to expand the neck at all, and the rod for the decrimping die was quite difficult to get in. Made it work, but I was worried I was going to crush some just-trimmed case mouths.
Results on the firing line were good enough for me.

[M1A4ME]

The expander enters the case mouth before the neck/shoulder enters the part of the die that resizes that area of the brass.

After you trim, do you chamfer/deburr the case mouth?  It gets rid of rough areas, angles the brass on the inside/outside which makes seating the new bullet easier (chamfered inside the case mouth right at the opening).

Every so often, as I resize rifle cases I can feel the expander ball "dragging" more than usual.  I scrape the case mouth of then next piece of brass to resize across the lube pad and that puts some resizing lube on/in the case mouth which then transfers to the expander ball on the stem of the primer punch in the resizing die.  You can feel things lighten up/smooth out for another 20 or 30 cases till you need to repeat.