AR Guys and Cast Bullets

  • 922 Views
  • Last Post 25 July 2018
sqlbullet posted this 15 June 2018

I thought a bit about resurrecting a thread as a zombie, but as a mod on another site I always cringe when that happens.  I have been catching up on all the fun you guys have been having without me, and just read the discussion on AR-postal matches.  I wanted to share a few of the thoughts I had as I read that thread.

I am big on AR's.  My safe has eight completed AR's that I call mine + most of the parts for a ninth.  The safe also stores an AR each for five of my six kids, my wife, my mother and my son-in-law.  They always took mine at the range, so I made them all build their own.  The sixth son is away right now but will complete his when he returns.

And, just in case, I have about 10 stripped lowers waiting on whatever idea hits me next.  Problem with lowers is they are often on sale for $30 and it is just so easy to order 3-5.  And my local FFL often charges a single flat fee for multiple transfers.  So, I tend to stock up anytime I get below three on the shelf.

I specifically build one of my AR-10's in 358 Winchester as a cast bullet gun.  358 Win just begs for cast bullets in my world view.  I built it light and handy too.  I have had some challenges getting function with 310 grain Thumpers, but I think I have those issues worked out now.  Next range session will tell the tale.  I also have a 280 grain SP mold.

I also have molds for the 30's (308, 300 Blackout) and for the 223's.  Like the 358 Win, the molds are for bullets that are on the heavy side for the caliber, running 200-230 grains for the 30's and 80 grain for the 223.

Lessons I have learned.

Plain base and gas systems don't get along.  After years of running BobS' load in my Garands with gas checked bullets I decided I was going to save some money and try plain base.  I got through 3-5 clips before I started having issues with the gun not going into battery.  At first I feared I had horked up the op rod, but eventually figured out it was just excessive lead build up in the gas cylinder.  Since then I am committed to gas checks, or a powder coat at a minimum in any gun with a gas system.

Ultra-light bolt carrier groups don't play nice with heavy for caliber bullets.  My beloved 358 Winchester "scout rifle" was built to come in at 6.5 lbs unloaded with iron sights.  Doing that in 308 is pretty achievable by using a pencil profile barrel and watching your weight elsewhere.  But in 358 my barrel options were more limited, and I ended up with a more medium profile barrel.  I ended up splurging on a v-seven titanium BCG to try to buy back some ounces. The gun just won't run with bullets over 250 grains.  It fails to go completely into battery.  It may be the 7.62 Nato brass I am using is not quite to spec, but I rather think it also could just be physics of the light BCG and heavy round.  I have 1K Starline 358 brass now, and I have checked headspace with a regular full weight BCG.  Next range outing will tell me if I finally have a gun that can run heavies, or if I need to order a 200 grain mold

So, having rambled a bit about how much I like AR's and how stupid I am sometimes in my build decisions, let me get to a point.

Right now AR's are cheap.  And they are easy to build.  And surplus ammo to feed them is cheap.

We mostly came to bullet casting via the ammo is costly, gonna save money, hey reloading and casting is really fun too route.  This new group is coming here via a different path.  Hey, AR's are cool, and wow, they are easy to build and cheap to shoot, but what other gun stuff can I DIY.

And I think that is going to be how AR guys get into casting bullets.  Like me, at some point, they are just gonna realize that no matter how fun AR's are to build, you reach a point where you just can't store any more.  When that happens, they are going to look for other fun to do, I did it myself, gun tasks, and cast bullets is an obvious answer.

Looking forward to developing better and more applicable information about AR's as well as learning from you.  Here's to aluminum rifles and tiny bullets!

Attached Files

Order By: Standard | Newest | Votes
Ken Campbell Iowa posted this 16 June 2018

great stuff !!  ...  " obsession ", hey?  ... i just call it " exploring the subject in depth " .... cool

i am not an AR guy but do wish i had friends who were ... so i could borrow their guns and expand my universe ... i am probably one of very few shooters who have shot an AR only about 6 times ... that was a colt match AR15, had a 9 lb trigger and jammed every other shot ....

.... but i know that when properly tuned they are a very good rifle ... and do have a thing for a good AR10 ... especially interested in the piston types ( ruger etc. ) ...  but waiting for the $350 AR10 kit ... every time i get a few fun bucks ahead i buy another old classic bolt gun ..... heh .  

whatcha think about an AR10 in 35 Remington ??   oh wait !! ...

please keep us up on your adventures ... the AR matches here for some reason haven't been heard from lately .... maybe you could put a little life in that direction ...

ken

 

Attached Files

TRKakaCatWhisperer posted this 16 June 2018

Ooooooo.  An AR-10 in 358 Win!   Where did you get the barrel?

 

Attached Files

Geargnasher posted this 16 June 2018

I prefer wood and blued steel, but the AR platform has become too easy, too useful, too cheap, and too much fun to ignore.  That's why I've built seven in the past several years.  I do the 80% lower thing, just because I can and it's an extension of the fun for me.  

It all started because I got a mad craving for a .45 ACP, semi-auto carbine and wasn't happy with anything else available (other than a Reising model 60 which wasn't great to start with and is in full "collector" status).  I got a DI-45 upper and quickly learned what you did about plain based bullets and gas systems.  Powder coating was the answer, so along comes another research hobby.  Then on to 300 BLK, with gas checks and heavy, subsonic bullets, which lead to collecting tax stamps from the ATF, and eventually more powder coating to save money on checks and keep the silencers clean.  Once I got all that sorted out, the Blackouts started mulitplying.  And getting cool paint jobs.  More paperweights got converted to rifles.  Dadgum things are out of control.

Then .22 rimfire ammo went extinct, so buckets of range-pickup .223 got cleaned up, mould bought, and another upper built, this time in the usual caliber.  But only for subsonic loads, 7-twist, powder coated, and suppressed, operated as a straight-pull.  Garage-sale primers, powder coat, and a pinch of Titegroup got me to the cost level of Federal bulk rimfire 20 years ago...and I could make all I wanted.

Then a friend stared inviting me to pig hunt SE Texas with him, and the .458 Socom barrel was soon in the mail, what the heck, I already had a .45 silencer.  Powder coated 500-grain cast bullet loads were developed and pigs slain.  Now I see what all these kids have been raving about!

I'm almost back to my senses now, restoring and fixing up more classic rifles again to shoot cast bullets, but the ARs are still a big part of the fun.

Some other things I've found on my own journey:  Extended-power buffer springs help put more pressure on the BCG when going into battery, particularly when using cartridges that have a lot more mass than the platform was ever intended to handle, as does honing any ridges or tight spots out of the buffer tubes with an oiled brake cylinder hone, then cleaning and greasing with a light, buttery lithium grease.  I use full-auto carriers and standard carbine weights in everything, just tune the powder type and charge weight to get things functioning properly.  Sometimes I have to dial the gas back or monkey with the gas port, but never had any luck with lighter buffers or BCGs for cast bullet loads.  

Attached Files

sqlbullet posted this 16 June 2018

358 Win barrel is from KAK Industries:  https://www.kakindustry.com/lr-308-parts/358-winchester-parts

I went with the 16" barrel.

Lower is TN Arms 308 lower. Yes, the poly lower will probably fail on me someday, but I have three more, and ultralight aluminum LR-308 lowers are out of my budget on most days.

Upper is a Fulton Armory 308 side charge upper.  No, it isn't a side charge bolt, but the side charge upper is lighter since it lacks a brass deflector, forward assist and has some additional metal removed for the bolt handle race.

As I mentioned above, V-Seven titanium BCG, which is also out of my standard budget.  Moment of weakness.  Primary Arms LPK, carbine buffer tube and a typical collapsible butt stock ( I was making up for the BCG price)

The gun has a standard A2 front sight base.  I am currently running a Magpul BUIS rear sight.  

I bought a cheap DPMS barrel nut and 9" carbon fiber front hand guard. It came with epoxy to attach, which I was not really thrilled about.  And it was really short.

So, I did some measuring and found some 6061T6 aluminum thin walled tubing at onlinemetals.com that seemed to have ID that matched the OD of the barrel nut.  When it came I lucked out and it was a great interference fit.  So, I cut the tubing off just .0625" short of the FSB and epoxied the barrel nut into the tube.  I used a Brownells barrel extension torque tool and a pipe vice to torque it down.

Finished product:

and final weight:

Attached Files

sqlbullet posted this 16 June 2018

I forgot about my 458 SOCOM barrel and upper.  This and my 260 have kinda stalled.  Daughter got married last summer and had the reception in my back yard, which was bare, unlascaped dirt 45 days before the wedding.  And now I am finishing up my detached garage/shop.  Sheetrocking today in fact.

I have most of the parts for the 458 and 260 builds.  Uppers, Lowers, BCG's, barrels, hand guards, gas blocks.  And I probably have enough parts for for most of the internals.  I will probably put a nicer cassette style trigger in the 260, but the 458 will get a standard mil-spec style trigger.  I am thinking A2 stocks on both of them as well.  I just gotta pour though the parts bins and make lists of what i need to order. 

About two years ago my wife asked when I was going to order parts so she could have an AR, and I scrounged a complete rifle out of the parts piles. So, I know what you mean about have a "problem".

Attached Files

shastaboat posted this 20 June 2018

Interesting clip.  I'm planning to build a designated cast AR sometime in the future to shoot cast 55 gr. exclusively.  I plan to use a 1 in 12" twist barrel or maybe a 1 in 14".  I'll also open the gas hole and fit an adjustable gas block.  Not sure if I'll need to use a reduced power recoil spring and lighter buffer.  Has anyone already built one like that?

Because I said so!

Attached Files

Geargnasher posted this 20 June 2018

No, I haven't built one like that.  Personally, I opted for the much easier 300 BLK which can be configured one time correctly and shoot anything with no adjustment.  For 5.56, powder coated, 3/4-throttle loads are easy enough through a standard rifle or carbine provided you have sufficient twist (12 minimum for rifle, 9 is better).  Depends on what you want to do and how much you want to invest.

Attached Files

shastaboat posted this 22 June 2018

 Well no, the trend for fast twist barrels and cast bullets just doesn't run together.  I have no need to shoot a heavy for caliber bullet in .223/5.56.  Since cast bullets stabilize so well in both my 1 in 12" bolt guns, that's where my goal is.  I also am satisfied with 2000-2400 fps and have no desire to go PC.  Guess I'm still old school.

Because I said so!

Attached Files

Geargnasher posted this 22 June 2018

Well no, the trend for fast twist barrels and cast bullets just doesn't run together.

 

True, but only as a trend, not as an absolute. surprised If you put a 12" ROT barrel on there and are comfortable with 2200 fps, all standard components (buffer weight, spring, BCG, gas block, port size, etc.) should serve you just fine, even with a 16" barrel, so I don't think you'll need to buy all the special parts to make it run.  Try WW748 and IMR 3031, and if you can get your hands on an MP 22-65 NATO bullet mould, jump on it.

Attached Files

sqlbullet posted this 22 June 2018

Yeah, I would agree you aren't going to need any special components to get it to run.   Standard carbine or rifle buffer, springs and a standard BCG will be fine. 

You hear guys talk about guns being "over-gassed" and "under-gassed".  The reality is that Stoner designed the gun to have a significant over-gas.  The way the system is designed it can vent un-needed gas easily, though some complain that the venting is into the action.  I don't have an issue with that given the other benefits.  Since the default is to have significant "gas" surplus, you have to back pretty far down before you get a gun that won't run.

 

Attached Files

  • Liked by
  • Geargnasher
Dukem posted this 05 July 2018

I  dipped a toe into the AR for cast use pool not too long ago when I bought a 7.62x39 upper and mags from Midway. My thought was I could get a semi auto and control my bullet availability issues and yet run full power if I wanted too. Trying to run semi auto functioning with a 22 caliber in a fast twist just seemed to be too daunting of a task. 

So far I have tried the Lee SKS bullet and the NOE 30 XCB paired with AA1680. Other than chasing brass this seems to be working out fine.

Attached Files

Brodie posted this 06 July 2018

 Dukem, you need a little  mesh bag that attaches to the ejection port like the Israelis use.  In fact: catch bags should be mandatory for any AR used on a range, and most if not all semi autos.  I so dislike getting hit by hot brass from the guy on my left.

\

B.E.Brickey

Attached Files

  • Liked by
  • Geargnasher
shastaboat posted this 23 July 2018

Yeah, I would agree you aren't going to need any special components to get it to run.   Standard carbine or rifle buffer, springs and a standard BCG will be fine. 

You hear guys talk about guns being "over-gassed" and "under-gassed".  The reality is that Stoner designed the gun to have a significant over-gas.  The way the system is designed it can vent un-needed gas easily, though some complain that the venting is into the action.  I don't have an issue with that given the other benefits.  Since the default is to have significant "gas" surplus, you have to back pretty far down before you get a gun that won't run.

 

 Gentlemen, I've already failed with standard components to get my 16" AR to function with my load which is LEE 55 gr in front of 10 gr of 2400 which gets me 2000 fps in my 20" bolt gun.  Even using a cut down spring and lightened buffer would not function.  This load is accurate and is deadly out to 200+ yards for me on squirrel and rabbit shoots.  I do not want to use 4895, 3031 or any other powder.  

Because I said so!

Attached Files

Geargnasher posted this 24 July 2018

Well, then you're going to need a lathe.

Attached Files

sqlbullet posted this 24 July 2018

10 grains of 2400 is going to be under-gassed a good bit.

So, I am gonna make a couple of assumptions.  One, that the parts you have are worthless to you unless you get the gun to run.  Two, that you are therefore willing to take some "extreme" measures to get them working.

You mention that you have cut down the action spring and moved to a lighter buffer without success.  Two questions as a follow-on:  Do you get extraction/ejection and not feed, or just extraction with the case left in the action/chamber, or not even unlocking the action?  Have you tried enlarging the gas port.

If you are getting ejection but not feed, you are close.  Drilling out the gas port on the barrel may do the trick.  I have had this issue on some pistol build that used super cheap barrels.  They had carbine spec gas port diameters (.063") in pistol length gas systems and short barrels.  The guns would short stroke, ejecting the spent brass but not getting the bolt far enough back to pick up a new round.  Enlarging the gas port to .089" did the trick.  As far as I know .098" is the largest gas port size commonly used on 223 barrels.

Next up would be to shorten the gas system.  This will give you a higher initial pressure and a longer dwell time.  But, as @Gearnasher says, you are gonna need a lathe to do that with your current barrel.  Or you are going to need to order a barrel with a short for barrel length gas system.

The irony of this is, an enlarged gas port may work and is relatively easy to try.  But if it doesn't and you are going to lathe the barrel for a shorter gas system, you don't want the big open port out there.  You will end up blocking it off and wishing it were still smaller.

I don't know what you paid for your barrel.  If it is a relatively cheap barrel, I would drill it, and if that didn't work sell it, making a full disclosure.  If you paid big money for a match grade barrel, I would sell it and get something with a shorter gas system.

Or be happy with your cool straigh pull bolt action :-)

Attached Files

Geargnasher posted this 24 July 2018

Light BCGs and light springs lead to lots of malfunctions if lightening is required for functioning due to insufficient pressure/volume of gas available.  Light BCGs are for another purpose.  Lighter springs have no purpose IMO.  Re-engineering the gas system to work within the load limitations imposed is the only viable option I can see.

Attached Files

shastaboat posted this 25 July 2018

I have the lathe and can certainly enlarge the gas port but I want a 1 in 12" barrel not a 1 in 9" or 1 in 8" that I have.  Question.  If I acquire a 1 in 12" with a standard rifle port is it feasible to machine the barrel for a 7.5" gas system and drill an additional gas port hole?  I suppose I could tap and plug the original gas hole but I am looking for accuracy.  This additional hole may tend to clog with lead. 

Because I said so!

Attached Files

shastaboat posted this 25 July 2018

That brings up an additional question.  If I acquired a 20" 1 in 12" twist barrel do you think I could find one with a carbine length gas system and just enlarge that gas port to get it to work with my cast bullet load?

 

Because I said so!

Attached Files

shastaboat posted this 25 July 2018

sqlbullet No, I did not get my AR to extract, eject or cycle with the reduced recoil spring and lighter buffer.  I understand the need to build with a shorter gas system or be able to load with enough pressure to cycle by use of 3031 or 4895 powder.  I want to build this AR to utilize faster burn powder normally used in cast rifle loads, ie...2400.  Criteria are:

1.  20" barrel; 2.  1 in 12" twist Chrome Moly barrel, ;  3.  Use of 55 gr LEE cast bullet with GC or similar;  4.  Appropriate designed gas system.

Quote,"Or you are going to need to order a barrel with a short for barrel length gas system."  This is what I want!

Because I said so!

Attached Files

sqlbullet posted this 25 July 2018

Nuance doesn't come across well in a forum, so please read my comments like we are discussing this over a beer (which I don't drink).

If the barrel you have is more than a budget barrel, I would sell it and buy an "interim" budget barrel you can destroy in testing.  I would drill and lathe it for a pistol length gas system and see what I get.  If your current barrel is already a budget barrel, then I you can skip the sell/buy step.

Here is what I am driving at...I would not want to spend a bunch of money on a 20" barrel with a slow twist and a pistol length gas system, only to find out it still won't cycle the action.  And I don't see any way to get such a barrel other than ordering a custom barrel.

Of course, you have a lathe...if you have the rest of the tooling and the skill, you could get a blank from Green Mountain for about $110 and turn, chamber and install the barrel extension yourself.  If you have to buy/rent the reamers and/or don't have these skills, the cost goes up beyond just your time.

I am really excited to see how this goes for you.  Trying to figure out when I could wedge in a trip to test some ammo that duplicates your load in one of my AR pistols.  Might be informative, but I just don't know when I would get the chance in the next month.

Attached Files

shastaboat posted this 25 July 2018

I see this as an uphill battle for sure.  I am still hoping that I can find a barrel maker that is already making AR 15 barrels.  It seems like and easy CNC thing to just change the location of the gas port but so far all responses to my inquiries have been negative.  I would like to know that my load would function one of your AR pistols even if it was just a couple of rounds into the dirt.  As you stated the port would probably have to be enlarged.  I wish I knew someone who is already shooting cast in a carbine or rifle length AR with an opened gas port and an adjustable gas block to test my load to see if they could get it to cycle.  If they were successful then I could build an AR copying their efforts.  

Because I said so!

Attached Files

shastaboat posted this 25 July 2018

Another tid bit of info is that I have been successful in getting my FN49's in 8x57 and 7x57 to cycle with 2400 in loads from 1800 to 2400 fps.  These of course have an adjustable gas system  and are direct impingement like an SKS.

 

Because I said so!

Attached Files

sqlbullet posted this 25 July 2018

I think you mean short stroke gas piston like an SKS.  It is not a direct impingement gun.

Attached Files

  • Liked by
  • shastaboat
Geargnasher posted this 25 July 2018

I have a 7.5" pistol, an SP-1 rifle, and an M4 carbine pinned/welded to 16.1".  I can duplicate your load.  The problem is none of these that I have will tell us much about a pistol system with a slow-twist, 20" barrel.  If I get time tonight I can give you an idea via QL predictions what will work, and can apply some of my experience with port size vs. pressure peak, curve, and dwell time (barrel length past the port) to get an idea of the requirements for port location with your load and standard buffer/machine-gun BCG, which is all I use, together with extra-power recoil springs.

Attached Files

  • Liked by
  • shastaboat
Close