44x1.6" BGML Like a 445SM rimless off of 308/30-06 brass

After making a couple 44x1.8"BGM rifles 1Biggun and I got to talking about an ar15 version last year. At the time there were cheap SS blanks with a 1:16.5" twist, I had an extra upper and a piston kit complete with handguards. So all I needed was a 450BM type bolt carrier, 450BM type follower and the rest of the parts were already on hand. Initially it was going to be a 44x1.7" but the cartridges looked very much like the 44x1.8" cartridges and would snap into the extractor when chambered. We tried a 1.6" and it was short enough that the bolt just pushed it forward and didn't lock it into the extractor where the firing pin could hit it. Not foolproof by a long shot but a little extra insurance should it happen. Run at the same pressure on average the 1.6" case is about 50fps slower than it would be at 1.7" which I can live with. Two barrels were made, one 16.5" and one at 14.5" with a welded on flash hider to bring it up over 16". A standard ar15 barrel extension was used and they were modified to big bore center feed style by milling the bottom lug down to make a big feed ramp. The same reamer as the 44x1.8" was used and a set of 1.6" headspace gauges were made.

Initially 30-06 brass was trimmed, expanded and reamed to make what amounts to a 1.6" long 44AMP. With the switch to a 1.6" case length came the happy coincidence of having the same case length and internal capacity of the 445SM. 445SM has a around 1000PSI more allowable chamber pressure than a 450BM so I back off of the 445SM data slighty for max when working up loads. Recently I made some more cases from 7.62x51 cases and found it easier and quicker than using 30-06 cases. Since the base dia is wider they are loaded with a standard 444Marlin die with lengthened seating stem and a 44mag taper crimp die.

I only have two 44 molds (240gr & 310gr) and so far have only shot jacketed in them. I hope to test out some of the cast ones next time out. I've also been looking at 350gr-400gr molds for suppressed plinking. Here's some pics of it being made. The pic with the paper plate is the first semi fire. Out in the back yard into sand at about 6'. The recovered 240gr xtp's are sitting on the paper plate.

1Biggun has the other barrel, hopefully he'll pop in.

How cool is that !!!! Makes for a nice thumper ! What kind of velocities do you figure you're getting ?

So far the Quickload guesses have been pretty close to the magneto speed results usually coming in around 15-40fps faster than the QL guess. For 240gr XTP's around 1800fps at the low end and 2000fps at the high end. I want to try some 265gr ftx and fp as well as some speer 240gr deep curl along with some 240gr and 310gr cast next time we go out. The QL guess is around 1700fps for the 310 WFN which will be interesting to see how close it is. Don't have a 20" barrel to test it against, but QL shows almost a 100fps gain. Went with the shorter barrel to make it more handy in a treestand.

No slouch for sure !

Looking forward to an update on this.
please post COAL w/ 310gr for reliable feeding.
What magazines do you use for this round?
Thanks

Hi jmsj, I'm using a USGI aluminum mag with the lips bent in slightly. 1Biggun is using a SS 450BM mag and also had to bend in the mag lips a tiny bit since the case is a little narrower. You have to load them like a 22lr, push the follower down and slide the base under the feed lips v/s pushing cartridges in from the top. The 310Gr WFN feed fine at 1.981" COL which is the only one I've tried so far. I've got 10 of them loaded up with 21.5gr 2400 which QL predicts will pretty mild at 1580fps out of the 14.5" barrel at 35Kpsi. Doesn't look like I can go up much past 1630fps with 2400 and stay under 40Kpsi at that COL. LilGun and W296 look like they are both able to go over 1700fps and stay within pressure limits with the 310gr with the same COL.

I've got all my 44x1.6" cases loaded up, 240gr XTP, 240gr Deep Curl, 265Gr fp, the 310gr and some 225gr FTX. The xtp's shoot great, so we'll see how everything else does. Next time I'll load more 310gr if they shoot ok and some 300gr sp Sierra's. It's one of the guns I'll be using this firearms season.

Never did update this thread. Shot the 44x1.6" upper quite a bit more with mainly 240gr XTP at 2000-2050fps and 265gr interlocks at 1980-2000 fps. It was in the upper rotation for hunting in 2017, and 2018 and it will still be in the rotation this fall. Liked it so much I hunted with it more in 2017 than I did the AR10 in 44x1.8". At the end of 2017 season, using one of the 22-250 bolts and extensions another 16" AR15 upper was made for 44x1.8" for mainly the 265 interlock at 2240-2300 fps. It is now one of my favorite deer hunting uppers. Pic of a 44x1.6" in the stand on a snowy day during the 2017 season and the 44x1.8" upper last season.