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Posted: 2/27/2006 12:51:41 PM EDT
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I was looking for an action block so I could remove the barrel from my Bushmaster A2 upper and put it on an A3 upper. I ordered the block from Midway and when I recieved it I realized that I did not order what I thought. The block I got holds the upper with 2 steel pins through the holes that mate the upper and the lower. You then put the block in the vise, but the only support it has is at the take dow holes. Is this good enough to change the barrel? Or, do I HAVE to get the block that wraps around the whole upper? Thanks! |
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You bought this: www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=730930 DPMS calls it the "panther claw". It is designed for changing barrels.... so I would have to say you can use it..... |
I still think the wrap around clamp type ones are the best out there. The LaRue anti roll device is a new modification to the AR system... so accessory makes just havent caught up yet. I would rather have the most solid action block, and have to modify it.... then have one that I questioned, without modification. |
I recall seeing somewhere that someone, maybe Steve/bigbore from Adco, says that for barrel changes, a piece of wood should be put on the flattop rail, and the receiver/block clamped in the vice top to bottom. I don't know if that's Steve being innovative & cautious, or if the directions describe that configuration, as I don't own one. |
| The block that I got from Midway does not go up into the reciever like the one FALARAK shows. Mine only holds the upper reciever at the pin holes. The directions did say that for an A3 upper you could put it in a padded vice sideways and change barrels. I guess what I want to know is if it will provid enough support to remove the barrel from my A2 upper? |
It probably looks like comp1911's in the post prior. Perhaps he can answer that. |
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On the instructions that came with my LaRue rail it shows a picture of the upper receiver turned sideways, clamped in a vice between two pieces of wood. I actually used this method to install my LaRue rail and it works just fine if you will only be doing one or two uppers. If you plan on doing a lot of them then get a good action block. The DPMS action block can also be clamped in a vice sideways. All you need to do is to use a piece of wood on the upper and once it's clamped down it's totally solid. As mentioned above, Adco has less expensive option for the Claw and the only differenc is that you have to clamp in sideways to install rails or barrels because it doesn't have the piece that goes into the receiver like the Claw. See below for pics of Adco's receiver block. 
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Mine is the DPMS Panther Claw and does have the "tower" that goes up into the receiver. I use it as pictured. Not sure how not having the piece in to the receiver would effect rigidity. I've done all my work as pictured, I would never do it per the directions you have. |
That tower that goes in the upper receiver only matters if you use the block like you have pictured because the whole thing is basically being supported by the take down pins. The piece that goes in the upper gives extra support so the upper does not get torqued. When the block is turned sideways and the upper padded with a piece of wood the reciver is fully supported on both sides and, IMHO, provides better and more uniform support than just the two pins. IIRC, other than the LaRue instruction manual I've also seen pics that Steve/Adco posted that shows a large batch real SPR's being made and the receivers were all clamped sideways in a vice between two pieces of wood. 
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Understood. I realize why the "tower" is there but don't know what the combined impact of it and the two pins is. I would venture a guess that the pins are doing most of the work and the tower is there to keep some bearing to prevent the upper from twisting the lugs out of the block. I would have reservations about clamping on the receiver that way but obviously it works. Again I've done 4 or 5 upper as pictued in my picture with no issues. But I don't shoot for some specified torque either. I tighten by feel 3 times, then for final tightening I tighten, then torque the the nut to align the gas tube hole and/or rail. |
Right on! 
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The very best most solid way I've found to hold and upper is Brownells AR-15/M16 UPPER RECEIVER MILLING FIXTURE. http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=20241&title=AR-15%2fM16+UPPER+RECEIVER+MILLING+FIXTURE It bolts up as solid as can be and seems to spread the load over the whole upper. I haven't seen anyone else use it to barrel an upper but I wouldn't do it any other way. Never a scratch on the upper. Just my $.02 |
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