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Moleman

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Reply with quote  #26 
STEVEOM, 

I've stuck with carbine length even on the 20" barrels.   The pressure curve per inch of barrel is pretty sharp compared to a 223 and they don't have the gas volume of the bigger cartridges.   Ideally the gas tube would be slightly shorter than carbine, but longer than pistol.   For a 14.5"-20" barrel with a carbine barrel the gas port can run between .090" and .095".  Pistol is much smaller and about normal pistol size.  The one on my pistol is around .068" and has a non-standard carrier/recoil setup.  For any length barrel I'd start small and slowly open up the gas port until the bolt locks back on an empty mag.  The pistol had a Burris scope on it, but the reticle started turning in the first 20 rounds so it went back to burris, and a red dot went on it.  Here's a pic of it almost done before getting a handguard for it. The magazine is a polymer Bulgarian AR15 mag with steel inserts in the feed lips.  It works well for cast bullets with wide blunt tips as it doesn't have anything down the center front of the inside like a Pmag has.  357AR-PISTOL-13.jpg

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helix6

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Reply with quote  #27 
I'm in for one of these after I finish my 6mm Mongoose. I've been trying to decide on a larger bore AR to compliment my 277WLV and 300BLK.
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SteveOM

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Reply with quote  #28 
Thanks again Moleman for all you have shared.
What the heck are Bulgarians doing making AR mags?
Isn't that veerd?
Mark, I really think this caliber could be a great addition to your line (but what do I know? Literally I mean that!).
Cheap brass, easy mags and bolts, cast boolit friendly, high energy at normal (my normal) hunting ranges.
14.7" to 18" light to midweight.
Lee or RCBS die sets.
Any ways, I'll quit whining, or begging, or whatever it is I'm doing right now :-)
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MGP

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Reply with quote  #29 
Quote:
Originally Posted by Moleman
About 5-6 years ago I was looking at making a 357mag ar15 upper and got to looking at a 357Mag-rimless and figured why not a 357Max?  At the time it was a "just because" build for me, but with the DNR regulation changed it can now be used for deer hunting in the "limited Firearms Zone" where I hunt.  I looked a great deal on the bellmtc site and was impressed with the hot-rodded loads for the 357Max.  I had a cheap $35 .357 1"20" timberwolf blank which wasn't ideal but would work for testing.  Since a rimless cartridge would headspace off of the case mouth a standard 357Max reamer wouldn't work.  So I made one based off the saami 357Max chamber drawings only modified for a case mouth shoulder.   Made a barrel with basically larger M4 feed ramp cuts and then looked at mags.  Pmags with the forward bullet guides removed allow rounds to double stack although you do lose a couple rounds capacity on a 20rnd and a 30rnd only holds about 25-26.  We mostly just target shoot or hunt so we have mainly just used 5 or 10 rnd modified mags.   The first rifle was very crude but fed and cycled the rounds.  I was able to test several different bullet types to see what it likes and didn't like.  Early on I tried 158 and 180gr XTP and 180gr SSP bullets from hornady.  They fed very well as did some 200gr SP sierra bullets.  What I found didn't feed well was blunt exposed lead bullets or blunt bullets that were long.  Part of the issue with the long blunt bullets was that the noses were inside the chamber before the bases were released from the magazine feed lips.  Trimming the feed lips on the mags slightly helped as did a deeper seating depth. 

With proof the concept worked I bought a Green Mountain .358" 1"14" twist barrel and made a new reamer with a properly sized pilot for the larger bore .350"-.358" v/s .347-.357".  A couple years later MI allowed straight walled cartridges between 1.2" to 1.8" and at least .35" for hunting in their limited zone.  I was all set and used my 357AR rifle that first year.  Hunting state land I saw many more other hunters than normal but eventually got a 6pt at around 60 yards. The 180gr SSP drove deep into the marshy ground after passing through the deer.  Couldn't be happier with the performance.  The exit hole for the broadside shot was a little smaller than a golf ball but larger than a quarter.
Moleman this is a nice round and not too far behind my 358 MGP. I just started testing my new 35 cal AR round from the 22 Nosler case. Only time will tell but I'm thinking your round and my round are as good as its going to get with these small case capacity. Great Job !!!!!
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Moleman

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Reply with quote  #30 
MGP, thank you.   I like the 358MGP and bet the nosler case will be great also.  I had thought about using 5.45 cases as the basis to gain a little case taper, but then that opened up the custom die set can of worms.  I've made die sets in the past, but wanted to be able to use a standard die set so I stuck with the 223 cases.  You lose a little case capacity and performance but 223 cases are cheap and often free as range pick ups.  It performs well at the ranges we hunt, so far the farthest shot by my son was rangefinded at 142 yds.  The 180gr SSP broke the far shoulder on the way out. 
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helix6

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Reply with quote  #31 
Just a couple of thoughts after splitting cases at the reloading bench for a little while:

Seems like it would be a much easier project to prep brass by just cutting it off right behind the shoulder. That would decrease the length a bit, but that would also help with magazine compatibility I imagine. I loaned out my brass chopping saw or I would do some test runs. Getting that .224 hole up to .357 is literally quite a stretch.

I'd be interested to see what Quickload spat out with the case based around a ~1.45" trim.

The new Magpul 300BLK mags might be a great fit either way for 357 Max AR or a slightly shortened version depending on the internal geometry - I'm assuming the ribs are moved to a much more friendly location.
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Bajabusdoc

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Reply with quote  #32 
Working on 1.4 case see "mini-mole" and photo of mag
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Bajabusdoc

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Reply with quote  #33 
357 ar brass steps. Anneal. Expand 277 wolv expander after one shot spray or lube of choice and set in sun. 308 expaner. Lube and sun. 35 Whelen expander. Then trim

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jpeg 0723171348.jpg (120.82 KB, 32 views)

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68BlackRifle

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Reply with quote  #34 
Whats the powder limits of grains with 180 grain . Was going measure how much h2o case is, but haven't  had a chance too  .
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Moleman

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Reply with quote  #35 
The case capacity varies a little bit depending on what brand of case you use, but generally I go with 34.8gr water capacity for the QuickLoad data.   With a 180gr SSP that gives you around 26gr powder capacity if loaded to 2.240" col. 
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kb31416

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Reply with quote  #36 
For what it's worth, sign me up for an 16" or 18" barrel if some are made.
I had contemplated a cartridge like this several years ago even to the extent of making a dummy round and coming up with a name: 357 KB Automax that would have had a headstamp of 357 KBAM! The goal was to use a 9mm AR barrel reamed deeper, but I paused to think about how to get around the blowback design of 9mm ARs with no gas system or locking lugs. At this point, 357 AR is fine with me.
Speaking of barrel length, is there any real benefit going from 16" to 18" if the objective is to maximize velocity? I don't want the extra barrel length if it will not produce appreciable velocity increase due to powder capacity limitations.
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Moleman

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Reply with quote  #37 
This is from QuickLoad, but my magneto speed results were pretty close for the 52K loads with the 16" and 18" barrels. Never did chrony the 20" barrel.  180gr SSP and W296 at 52Kpsi-  16" at  2127 fps,  18" at 2170 fps and 20" at 2208 fps. At 59K you're at 2207 fps with a 16" barrel and 2250 with a 18" or 2287 with a 20".   The col was 2.240" if you have QL. 
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battle rattle

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Reply with quote  #38 
Quote:
Originally Posted by Moleman
Ideally the gas tube would be slightly shorter than carbine, but longer than pistol.

I've been dig'n deep the last few days, ran across this

http://columbiariverarms.com/gas-systems/
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Moleman

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Reply with quote  #39 
Neat!   That should help get the gas port smaller than the  .090" on a carbine length.   I've modified existing gas tubes for custom length gas tubes before, but it never bugged me enough to make one for the 357AR. Looks like a good option if someone wanted to try it out. 
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jnfarra

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Reply with quote  #40 
I was pestering Keith about this one early on before moleman commented with his. With enough lead time to know when barrels will be available, I would be interested in one.
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68BlackRifle

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Reply with quote  #41 
Moleman
You ever try 200 grain round nose in this set up 35 REM bullets . Should feed good , and speed is right there with 35 rem so should perform ok .

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68BlackRifle

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Reply with quote  #42 
Got a SS GM blank on my bench and playing wait game now for reamer . Just think this be a lot of fun to play around with . 
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Moleman

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Reply with quote  #43 
One of the first bullets I tried was the Sierra #2800 .358" 200gr Round Nose bullets.  They fed ok but not as slick as the xtp's or SSP bullets.  It sounded as though they were slowing down the bolt slightly but would chamber, perhaps it was just a different tone?  I think I only tried them with 2400 and W296 and haven't ever taken them hunting.  With that wide exposed lead I'd bet they'd do well. 
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68BlackRifle

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Reply with quote  #44 
Shot some in SaberCat they where accurate enough.
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68BlackRifle

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Reply with quote  #45 
Working on a mag ,,, this round will defiantly test ones patients. With brass work and all , setting here with a file and mag , just thinking this is nuts but I hope the payoff is worth it . Funny how you forget all that aggravation after the boom , and you pull the trigger again.
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Moleman

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Reply with quote  #46 
Dremel with a sanding drum removes the bullet guide pretty fast. 
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helix6

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Reply with quote  #47 
Moleman, do you have any photos of what you did for the barrel extension? Did you blend the receiver and the extension or just enlarge the ramps? If MDWS was to offer barrels, I imagine this would be an area of concern.

Also, what kind of blank did you use - 9mm or 358 rifle?
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Moleman

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Reply with quote  #48 
I'm camping this week so I can't get a picture of one of mine. I've modified the extensions two ways. One by just opening up the standard feed ramps to 3/8" which works but is weaker than just blending the two feed ramps into a trough like the big bore extensions. The last 5 or 6 barrels I've made have been the big bore style and that is what I'd recommend.
For barrels, there is a much better bullet selection for 180gr to 230gr bullets in.357/.358 so that is what I use with a 1:14" twist. Most light grain thin jacketed bullets going twice their intended speed or faster won't hold up well once they hit something.
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68BlackRifle

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Reply with quote  #49 
Barrel and reamer is in , did you drop 10% under 357 Max start loads to get your loads going , My friend had 6 Browning 1919 was converting over to 308 on bench so may be a while until i get to play .
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Moleman

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Reply with quote  #50 
The first one I started with 357mag and worked up.  Every one since then has been a 357Max starting load.  Check your brass though. The water capacity of 1.6" fireformed  converted 223 brass should end up slightly more than or at least equil to 357Max's water capacity. 
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