312-155 blackout jamming

[Blksnk]

Hello all! New here to the boards. Been reloading for around 7 years and casting for 2. I have a Lee 312-155 2r mold and a stag left handed 300 blackout upper. I am using wheel weight lead to cast and powder coating tumble method. These bullets are being ran through a Lee. 311 push through sizer with a gas check and I can not get these bullets to chamber reliably. Every other load works like a charm with fmj or sst or what have you. I have changed overall length down to 1.890 and it still sticks just a touch and won't fall out of chamber. I have seated a non coated bullet and dropped the bolt and no marks on the bullet at all. I'm lost, only thing that comes to mind is neck of bullet after seated is. 334 has anyone ever heard of this or could hand some advise my way. I hear nothing but great things about this cast Bullet but I can't seem to figure it out

[alfloyd]

To get a boolit to work in the Blackout, you need to be sure the nose of the slug is no larger than 0.300 inch in dia.
Other wise the boolit will stick in the bore of the barrel.
I had the same problem, so I made a sizer to sizer the nose down to 0.300 inch after powder coating.

Lafaun

[Blksnk]

Thank you for the reply! Would you mind elaborating on this setup you have? This has been driving me nuts for 3weeks now. They will work hit or miss and seems like some won't allow the bolt to close and it's just not reliable so I'm up for anything, the ones that chamber by force (but don't have marks or get set back in the case) shoot great

[petroid]

^^^That boolit is designed for 7.62x39 and has a nose that is .302-.303" If you have a snug chamber, which it sounds like you do, the PC fattens up the boolit to the point that you have to load dreadfully short to chamber reliably. A push thru sizer will not fix this. You can do what alfloyd did but will have to tap boolits out of the die each time with a push thru sizer or if you have a lubesizer a .300" nose sizer will work. You may get better results with a mold that is designed for .308 bore rifles. You could go so far as to ream or lap the throat but that may be too drastic. I would suggest a pound cast of the throat. You will get a picture of what the throat is and can measure off it so you know what it will take to get your rounds to fit. I guess I am lucky that I can load that boolit to 2.010" and chamber reliably. I have used Lee Alox lube with good results up to 1800fps. If the PC makes the boolits too fat, there's always Alox, but a bit messy.

[Yodogsandman]

That's some great advice! I'd just like to add that the new Ben's Liquid Lube isn't nearly as messy as straight LLA.

[runfiverun]

your boolit is too big.
most likely just the nose.
you'll have to ascertain if you have enough neck clearance for the body diameter first.
then see if the nose is stopping you from chambering the round.
look for scuffing or rings built up where stuff is hitting the rifle.
you may have to just size the boolits body one size then resize just the nose to get the appropriate diameters.

[1johnlb]

I don't pc and have to size to 309 or mine won't chamber because of my military 556 converted cases. My chamber is to tight for 311, even without pc.

[blikseme300]

I don't pc and have to size to 309 or mine won't chamber because of my military 556 converted cases. My chamber is to tight for 311, even without pc.

A little thread drift: Not all military brass are suitable for conversion as most foreign brass have thicker walls. There are numerous posts about this on this board.

Blksnk, even though this boolit was designed to work in the 7.62x39 it is being used by many 300blk shooters with great results. I don't PC but size to .3095 using Carnauba Red through a Star and add a Hornady GC. In 3 different 300blk AR15's of mine these boolits work well.

[alfloyd]

Blasnk - "Would you mind elaborating on this setup you have?"

I made a sizer die for my RCBS lube-sizer to just size the nose of the boolit to 0.300 inch.
It does not have any lube holes in it as I only use it to size powder coated boolits.
This way I can push the boolit down to the top lube groove and then push it back out with the up stroke of the handle.
It works great for reducing the nose size up to about 0.005 inch in dia.

Lafaun

[1johnlb]

A little thread drift: Not all military brass are suitable for conversion as most foreign brass have thicker walls. There are numerous posts about this on this board.

Blksnk, even though this boolit was designed to work in the 7.62x39 it is being used by many 300blk shooters with great results. I don't PC but size to .3095 using Carnauba Red through a Star and add a Hornady GC. In 3 different 300blk AR15's of mine these boolits work well.

No sir not drift. He's asking for help. Yes, maybe outside the rim of thinking of the rest of the group but that's just me, thinking outside the box and paying to much attention to what the op said.


They will work hit or miss and seems like some won't allow the bolt to close and it's just not reliable so I'm up for anything, the ones that chamber by force (but don't have marks or get set back in the case) shoot great

In case you missed his statement " don't have marks or get set back in the case". Reads to me that when he forces them in with the assist they don't have marks or get set back and shoot great.

If his boolit don't have marks or gets set back then maybe just maybe he's looking at the wrong area. Maybe just maybe his case neck size with a 311 sized boolit is to big. This is what I ran into. And regardless of what kind of brass I use I expect my ar to cycle flawlessly, and since sizing at 309, and throwing the s&b and ppu brass out I have no more problems.

[GRUMPA]

Since the OP is getting hit and miss results this sounds more like he's using different head stamped brass. Seems to me that the way he's making his boolits either they'll all fail or all work, instead of this every now and then failure rate he's getting. So if he has some that work and some that don't where's the variable?

To me the variable sounds like the case itself.

Either the head stamp varies or it's his loading technique. Sometimes depending on what type of crimp he's using and length the case neck can get a slight buldge giving varied results.

Just my .02

[petroid]

Every other load works like a charm with fmj or sst or what have you. I have changed overall length down to 1.890 and it still sticks just a touch and won't fall out of chamber. I have seated a non coated bullet and dropped the bolt and no marks on the bullet at all.

He says a non coated boolit chambers just fine. This leads one to think the PC is the offender. However, he doesn't say how many and what different types of brass he has tried this with. And I'm not sure on this one but if all the jword loads work fine maybe the brass is ok unless the .311 boolit is causing the issue here.


Blksnk we need to know what types of brass you are using and if they are converted 5.56/.223 or factory 300BLK. Also what types of brass did you use when seating your naked cast boolit.

Oh and what was the max OAL you could seat the naked cast boolit and stil chamber

[1johnlb]

Oh, come on that's more like a dollar and a half coming from you

[Blksnk]

Hey sorry for the confusion I might have had. The non coated bullet I seated to 2.000" did not have a y markings on it from where it might be hitting, however it still won't drop in chamber and fall out. In fact, non of my 312-155 have done that unless I seat them down to around 1.890" I have measured a lot trying to solve it and I just can't. Nosing the bullet down seems like what might be my problem I just can't visualize how I would do so. My brass is pmc and R&P. All trimmed on Lyman lathe and crimped the same with taper crimp. I think a pound cast would be good but I don't have means to do that quickly. Even the bullets that do get chambered and fire don't have set back measurable more than. 002 which is OK to me.

[GRUMPA]

OK Back up a minute, you know there's 3 different head stamps for PMC brass. Work with the ones with the LARGE lettered PMC, the other 2, medium and small lettering are foreign made.

[Blksnk]

Hey sorry for the confusion I might have had. The non coated bullet I seated to 2.000" did not have a y markings on it from where it might be hitting, however it still won't drop in chamber and fall out. In fact, non of my 312-155 have done that unless I seat them down to around 1.890" I have measured a lot trying to solve it and I just can't. Nosing the bullet down seems like what might be my problem I just can't visualize how I would do so. My brass is pmc and R&P. All trimmed on Lyman lathe and crimped the same with taper crimp. I think a pound cast would be good but I don't have means to do that quickly. Even the bullets that do get chambered and fire don't have set back measurable more than. 002 which is OK to me.

[41 mag fan]

When you size your bass what press are you doing them on? I had trouble with mine and found out it was my Hornady lnl. The plate had spring to it. I switched to sizing on my Lyman and problem solved.

[Blksnk]

Press is a rcbs single stage rock chucker. I'm not sure on which brass I'm using I think it's big letter brass. I have also loaded 125gr sst and 110vmax and don't have issues at all. My necks with seated pc bullets are. 334 +-. 001. Like I said I'm stumped because there are never marked on the bullets that I can see

[popper]

Probably will only chamber 0333 at the largest. If not sized after PC, the case can get expanded too large. Mic them. Try sizing 0.310 and loading, may work. Alloy hardness & neck thickness come into play as well as nose diameter. I have to size 0.3085 to get my boolit (31-145C - 0.297 nose) to fit the bore and check every case neck. for 0.333. I find some cases appear to have neck thickening after being fired in the same gun/load/boolit/sizing. I've annealed (candle method) to see if that makes a difference. I get to pull the ones over 0.333, then punch the primer & neck turn or toss. I seat to 1.80 or 1.90 to get it to work.
Even the bullets that do get chambered and fire don't have set back measurable more than. 002 Don't understand that statement.

[petroid]

Ok sounds like your brand of brass shouldn't be an issue but just to be sure measure the ID and OD of an unsized, fired case's mouth. ID will be largest diameter boolit you can fit but probably best to go at least a thousandth smaller. OD is your absolute max neck diameter of a loaded round. If all your ammo meets this criteria, then you shouldn't have a brass issue unless your unloaded, sized cases won't chamber.

[Blksnk]

OK I just went and played with it some more. My results are this. My sized pc bullets are coming out at .3105. My case wall thickness is averaging .012. I seated a non coated and a coated bullet all the way down to 1.850". Still not chambering freely. I decided to just keep racking the same bullet in and out many times, only thing I'm seeing is light scuff marks on the neck and size after working it that many times went down. 005. So maybe they are to thick. Should I grab a 309 sizer and see what happens?

[Blksnk]

Also, my jacketed bullets are running . 332 max and average at the neck. the 312-155 gas checked and sized at. 3105 are coming in around .336 max and .334 low sounds to my like these bullets are to fat. Question is will I loose much by obtaining a smaller sizing die still coating and gas checked

[427smith]

some of these post are telling you your bullet might be to big or brass to thick for your chamber. This has happened to me. I used a felt pen to paint the entire case neck to find this out.

[blikseme300]

Seems that it is not the boolit nose being too large that is causing the sticking but that the problem lies in the case neck area and this is where I would focus. Diameter alone may not indicate a problem but there could be distortion of the case during the seating and crimping as Grumpa mentioned in post #11. Blksnk, could you let us know what dies you are using?

[Blksnk]

I am using the rcbs sb die (black box) and then sizing with a Lee .311 push through after coating and coming out to .3105 for expanding I'm redneckin it by using a 9mm expanding die to barely kiss the edges then tc with the rcbs die

[flyingrhino]

I'm using the same bullet. I pc then size with .309 Lee push through. Seat to 2.055 and they run flawlessly. I only use Winchester .223 brass to make my 300 cases. I had neck thickness issues with some others. These average .011" thick.

[petroid]

Measure OD of a fired case mouth. This will tell you the max that will fit in your chamber reliably assuming about a thou of spring back. Find a brass headstamp that gives you the neck thickness you need. And you may have to size to .309. And do a pound cast. It will tell you what you need to know about your chamber.

[runfiverun]

the 300's are picky about the brass thickness.
I have grumpa saving brass for me right now as I need some .0012 brass for my jacketd 308 bullets.
the brass I use now is .0010 and I size to 310, this gives me .001 for the case to open and release the bullets.

another thing that might be popping up here is that there were some dies made that had some dimensional issues, they weren't sizing the cases quite right in some areas [the neck/shoulder area] and this of course would cause issues.
airc they were made for the 300 whisper which is super close, but tolerance stacking in the dies and in the rifles can lead to a mis-match.

[popper]

Also, the taper crimp MAY be buckling the neck a tad. I use the FCD just to remove flare. No setback in BO or 308 AR. Don't over crimp. With the brass thickness all over the place in reformed, get a proper expander plug to be determined after you find the size of boolit needed.
edit: flare with needle nose or a proper tool, 9mm expanding die is NOT.

[1johnlb]

My 1 and only rcbs 30/30 buckled the neck if the brass wasn't uniform causing chambering issues. I've also run into issues with case spring back on the 300blk converted cases and had to size the cases twice to solve it. This sounds like neck diameter though a Lee 309 push thru should solve it. 309 is still plenty big for cast without issue.

[wcp4570]

I have found that PMC brand brass yields a neck thickness that is too thick for making 300 brass and needs to be neck turned or reamed. I size my 312-155 to .309 and if seated in PMC formed brass it will not chamber in my barrel as well. Because of my experience with PMC brass I only using LC brass to making my 300 Blackout brass and don't have a problem.

wcp

[Blksnk]

I have measured my brass with pmc, rp, Lc and fc and all are within same range for me so I'm working on finding a friend or anyone who has a 309 sizer close by to make sure it's gonna solve the issue. I'm certain it'll make a big difference. Although as some have stated my bullets are fat and after I fix the size issue I may find that to be some trouble to. One thing at a time. I will figure it out and post back with my results and again thanks to all who have helped and gave great advice. Great site!

[rockshooter]

I had the same issues with this bullet- it is related, as noted, to the diameter of the nose and not to the cases. I finally cured the problem to switching to a NOE version of 311414. I found that in sizing the Lee to .311 I basically erased the lube grooves.
Loren

[Fishman]

I had the same issues with this bullet- it is related, as noted, to the diameter of the nose and not to the cases. I finally cured the problem to switching to a NOE version of 311414. I found that in sizing the Lee to .311 I basically erased the lube grooves.
Loren

That was my fix too, but my last batch had a slightly larger nose diameter and wouldn't chamber 100% of the time. I'm thinking some chambers would benefit from opening the throat a bit but I have never done that. Kinda frustrating.

[beltfed]

I think your problem may be in the body dia of the bullet and maybe also on the nose dia:
For reference, below are the SAAMI chamber specs for the 300AAC BO:
Chamber Neck dia : 0.3370 at shoulder/ 0.3350" at mouth
Freebore: 0.3090" x 0.187" long
Leade/throat: 1 deg 30min per side.
Above are SAAMI Minimum chamber dimensions
Tolerences are All dia "+0.002
Length Tol are "+0.015"
I am sizing my cast bullets to 0.309" for my Hardened Arms upper
and the top drive band of the bullet can be no longer than 0.187"
as per the freebore length.
the Lyman 311299 bullet fits this ctg very well and I am getting
good accuracy out of it in "full" loads.
Now working with the NOE 311-247gr bullet
Alloy is 9+1 WW/Lino
beltfed/arnie

[popper]

Which agrees with the 0.333 max loaded OD to chamber. 0.002 clearance so you don't have to pound it home. Dirt, oil, anything naughty.

[Blksnk]

Ok, some results after work. Took a non coated bullet and a powder coated bullet (cut off gas check). Lightly with sand paper, sanded them down to .309. The necks with pmc brass are coming in at .333 max. The coated bullet will chamber freely at max 1.995 and Un coated bullet to 2.000. So, obviously my bullets were to fat. As predicted I'm also running into the front half being fat as well so my? Is will I be OK to run these bullets at 1.990" or should I just buy a different mold?

[1johnlb]

Start from scratch with a 309 push thru, don't over complicate it.

[popper]

I run mine at 1.90 or less, no problem, but it's not the Lee. No pressure problems with full case of 4227, which you can load compressed. Just load what you got and get results.

[Blksnk]

Sounds good. I'm gonna get a 309 push through sizer, and test them to make sure issue is gone. Another thing I can do to help is my powder coating method. I am using my tumbler and powder from Eastwood. I was doing 3 coats to get 100 % coverage but I ran a few with one coat and a few with 2 coats and in fact the third coat is adding a lot so I'm gonna stick with 2 coats and deal with them not being perfectly coated. I'm thinking with the gas check it doesn't matter all the much if the tops are coated as well as long as the drive bands are coated well. Thanks again for everyone's help much appreciated! I will report back with real range proof of this fix

[kweidner]

Bore riders and PC/ coated with semi auto are begging for issues. Easiest fix would be to seat deeper and rework load based on new depth. I created 2 BO molds because of this. Both are subsonic designs though. I ran into same problem with NOE 247. These are all fantastic molds but designed before we were coating. Encore loves NOE. Once I stuffed it deep enough AR would tolerate it. Just wanted to go my own route thus my custom HT molds from Tom. I have just gotten him to make me a set of the 215e for bullet master after thorough testing. They came in last Thursday and I did over 20k this weekend.
In my opinion this is like everyone marketing Sierra 220 with BO. They are using a bullet designed to open over 1600fps and wondering why they are wounding animals. Use a design that is for subsonic and BO. I also swage a subsonic open tip, hollowpoint opening design. It will open at 900 fps. Lets make bullets for specific purposes. Would you shoot a rabbit with a Barnes mono or shoot a moose with a varmint ballistic tip?

Pick the right tool for the job. Most manufacturers are starting to figure this out. Mr. Nelson is offering some coating specific designs and Tom's catalog is full. There are at least 3 major manufacturers offering coated boolits in the states and little old me and a few other smaller vendors.

For the past year I have been doing just local/ regional stuff. Plan on getting vendor stuff here and webstore in the next couple weeks.

I really love the Blackout. It is a super fun round and loaded correctly sounds like a mouse passing gas suppressed. I do have one supersonic design I do not sell in a 155gr rebated boat tail. Honestly though There is more demand for the subsonic capable boolits and bullets. More demand from my standpoint too. I just posted this in another thread but nothing like. pfffffft.......wait....wait....wait.......CLANG! Will bring a smile to your face everytime.

[beltfed]

Have to agree with kweidner. Must use correct bullets for the purpose. So, last fall, I worked up a load for
the 300 BO for Wi deer hunting:
A Hornady 160 gr FTX bullet that was designed for the 30-30 and the 308 Marlin Express. Both versions are boat tail secan ogive nose,plastic tipped. Designed for good expansion at only 1600fps, but built to stay together. My load is running about 1900fps from the 16" barrel. Good accuracy.
Should be good for up to 100+ yards-
about as far as I am likely to shoot at a deer in the Wi North Woods.
Also, working on a load for the 130 gr Speer semiFN that was designed for pistol velocities.
beltfed/arnie

[Blksnk]

Update: sized all rounds to 309 bullets now fall into the chamber and drop out. I'm loading them now at 15.3gr h110 and 1.970 coal. Shot 30 rounds at 50 yards today in the yard and they all went bang and no hiccups. Thanks for all the advice and posts. I may eventually size nose down but for my cheap plinking round I think these are just great.

[petroid]

Good to hear! I'm guessing you're about 1800fps with that load. Maybe a little more. Pretty close to what I load for plinking. Play with OAL and see if it helps your groups or just load em and shoot em. It's all good

[popper]

30/30 & 308me are not the same bullet, ME is built to run 2700. You can shoot them but terminal performance is NOT the same. I can actually run Sierra 170s through mine.