Del-Ton AR-15 question


Well-Known Member
Mar 16, 2009
pabst, wisconsin
I traded a MOA Specialty Pistol for this gun a while back and I'm having issues with it. Every once and a while when a round is chambered the bolt will not open. The only way to release the round and bolt is to remove the barrel. This only seems to happen with reloaded rounds but I have shot few factory rounds out of the gun, maybe 60 rounds.

I thought I fixed the problem by scrubbing the chamber real good but today it happened again without firing it. I simply chambered a round and the bolt refused to open. It almost seems like the bolt face is not rotating fast enough???

This is the first and only AR that I have reloaded for and It may be my error butmy other semi autos have no issues with my reloading. When I reload I first re-size and de-prime my spent brass with a SB FL sizer die. I than tumble it, clean the primer pocket, debur the flash hole if necessary, trim to specified length according to my Hornady manual if necessary, and chamfer the inside and outside of the bullet neck.

I'm not sure what the deal is??? Either I'm doing something wrong or the gun is??? Could I be leaving lube on the cases??? Opinions on Del-Ton???

Have you measured several loaded rounds yet? Base to ogive and the diameter of the base , neck dia. etc. Try chambering resized brass only . If all that checks out then I would move on to the chamber but more than likely the dies need to to be adjusted or your are using brass that was fired in a larger chamber and the brass is springing back after you size it. I had that trouble also .Did you say Factory loads cycle fine ?
Chambering resized brass has the same results only every piece of brass jammed. I measured 7 loaded rounds and everything came to be within .002" except the OAL which deviated .005", but that length didn't seem to reflect weather or not the issue would persist. All the brass I'm using was factory ammo shot out of my gun that I'm reloading.

I believe I had this problem the first time with factory ammo (can't remember for sure). Other than that it has all been reloaded ammo.

So reloaded ammo jams, and your trimming the cases? Does it jam so bad you have to shotgun the weapon to cycle the bolt? Seams to me like you have a bad bur in the chamber or your extractor is shot. I know this is a lot to ask but can you make a video? If its jammed up hard its a different issue than its just not extracting rounds.

What are you using for lube and how much? AR's are like porn stars you have to lube them and lube them a lot!
is it 223 or 5.56?

223 is a shorter chamber, no?

Is your re-sizeing die set to high in the press?
I'm a little busy to post a video this weekend but I did notice a decant scratch going down the casings and even the bullet it self. I tried to clean the chamber with a wire brush that fits in the chamber, the neck of the chamber and the star chamber, and than I scrubbed it with solvent.

I can not see any burs inside the chamber with the naked eye but I'm no gunsmith. After that I put it all back together and and cycled some rounds through it. The first one was smooth and the second one jammed. I have found that I can separate the lower from the upper and pry the bolt carrier open with a screwdriver pushing toward the front of the barrel without too much pressure.

When your resizing brass is the die adjusted so it touches the shell holder if not its leaving the base of the shell expanded and will jam when the bolt slams shut.
readjust your die and re resize a shell and see if it cycles in and out freely of the chamber.
Well I feel like I have tried just about everything and some, and I still have the same issue. I'm getting pretty feed up so it looks like I'm going to have to take it to my gun smith.

Thanks again for all the suggestions.
Hey Ryan,

Don't go giving up just yet, I think this is an easy fix. I don't have access to my computer where I right now, and a long answer via my phone is a bit tedious. I think you've got a simple sizing issue, and we can clear that up pretty quickly. I'll be back in the office on Monday, and can get into a longer exchange then. Trust me, we can get you up and running in no time.
No problem at all, and I can appreciate the frustration. If you're already loading for a Garand and not having any issues there, that's a real good sign. Loading fro Service Rifles (ARs included) is a form of advanced handloading. Easy to run into problems here that you'll nearly never see with a bolt action.

The first thing I'd suggest is to use a case gage. This will tell you what's going on, and allow you to know what you're changing when you start trying to adjust things. Without them, you're essentially loading in the dark. I'd suggest something like the RCBS Precision Mic, but there are several different types out there. Even the simple L.E. Wilson chamber types will allow you to nmeasure what's happening when you start adjusting the dies. What you're looking for here is to set the shoulder back to approximately the dimensions of a new, unfired loaded round. Once you have a measurement for cases that have been fired in your chamber, you can look towards setting the shoulder back to about .003"-.004" under fired dimensions, but for starters, just use an unfired round. Use the gage to adjust the sizing die to a point where the resized cases have the same datum line dimension as the unfired rounds, and see if these cases chamber properly. If not, then it has to be a radial dimension issue that will need to be cured. That may entail a Small Base die.

SB dies aren't always required for Service Rifles, but they don't hurt a thing and can solve a ton of problems. As far as the "excessive brass working" that many get so excited about, it's nothing, and well worth avoiding the potential problems I mentioned. Many handloaders aren't fully aware of this, but standard FL dies do NOT resize cases back to their original unfired dimensions. SB dies get a lot closer, and that's what we're looking for here. Using the SB dies, in conjunction with the case gage to set your datum lines should resolve the chambering issues completely. While the advice to adjust the bottom of the die down to the shell holder is what's specified in most manufacturers instruction, it really is a "one size fits all" approach. It works in most instances, but isn't really the ideal way to adjust these things. You may find that the die will work properly when adjusted that way. Or, it may be sizing the brass excessively. On the flip side, it may also not be pushing the shoulder back far enough, and need to have some material removed (ground) off either the shell holder or die to reach the proper fit; I've seen several instances of all three.

Start there, and see what happens. Give us an update, and if there's any issues that remain, we'll dig a bit deeper. Either way, we'll get it taken care of.
I do not have nor have I ever used a precision mic I will look into them, but I do use a RCBS small base die. That is the only die I have been using for resizing.

I took some measurements with a micrometer of my reloaded round with 223 brass and of a loaded factory Lake city 5.56 round that chambers and cycles fine and this is what I came up with:

oal: 223-2.220 (after I adjusted from 2.267)

Neck: 223-.245

Shoulder: 223-.355

Base: 223-.374

Rim: 223-.374

I tried to take pictures of the two up close but my camera will not work with me and focus. If there is anything else I can do let me know. In the mean time I will look into a precision mic.
No problem at all, and I think the Precision Mic will help here. You might also look at teh bump gages that Sinclair and a couple others sell as well. Both of these gages will measure the same thing; the actual length from case head to datum line, which is where we determine our headspace dimension. All of the measurements you've listed here (with the exception of the OAL) appear to be diameter readings, and I don't think that's your problem. The Precision Mic or bump gages will allow you to verify that you are in fact pushing the shoulder back far enough to allow the cartridge to fully enter the chamber, and the bolt to close without binding anything. It also enures that the case is entering the die far enough to take the radial measurments down to where they should be. One other thing; make sure you run these slowly when you resize. Running the case all the way to the cam point (where the press toggles over), hold it there, at least to a count of five. Brass is naturally resiliant and has a spring back factor, which is precisely what makes it the material best suited to making cases. However, that same resilliancy allows it to spring back out a bit if it's simply run into a die for a moment and then pulled right back out. All the way to the top of the stroke, a count of five, and then lower the ram. It makes a difference.

I'm curious as to why the OAL is so short, though? Nominal specs for a 5.56 or 223 Rem is going to be right around 2.260". I generally run mine at 2.250" to 2.255" just to allow a little clearance with the front of the mag. What bullets are you using, and how did you arrive at the 2.220"-2.227" dimension?
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