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Posted: 4/12/2006 2:52:33 PM EST
[Last Edit: 4/12/2006 2:53:23 PM EST by Gunzer]
The action block available from Bushmaster folds around the upper receiver and is then held in a vice. There is another type of action block that makes use of the front and rear pivot pin holes of the upper receiver.

Can an argument be made for one type over the other?

I have three complete uppers from Bushmaster. On each of them I can tell where the action block contacted the upper.

Does anyone know if the pivot pin designed action block can handle torquing barrels on and off as effectively as the wrap around design?

Thanks,

Gunzer
Link Posted: 4/12/2006 3:45:21 PM EST
This was covered here recently. I’m skeptical about the DPMS tool. I have the Bushmaster and it works just fine. So what if it leaves a slight mark on the upper during assembly, can’t see them anymore after some time and CLP.

Plus, my weapons are not range queens.
Link Posted: 4/12/2006 4:03:38 PM EST
[Last Edit: 4/12/2006 4:18:02 PM EST by kells81]
this was somewhere here last week, dont waste your money on the DPMS action thingy. It is not for barrel work. buy the Brownells model.

looks like this, leaves a shiney spot on upper, but thats ok in my book.


I supports most of the reciever, the DPMS does not,


DPMS model


heres a topic

and another topic
Link Posted: 4/13/2006 1:26:02 AM EST
ADCO sells the Schuster Upper Holder. Their site shows a picture of it mounted sideways with a piece of wood against the rail of and A4 upper. It's ony $28.00 and if you wanted a no marks on your flat top this might work just do the trick.

Link
Link Posted: 4/13/2006 2:14:41 AM EST
Just use the barrel blocks like the Army did for years. No marks on the upper, and you can properly boresight the barrel so no canted front sights.

Boresighting is not possible with the clamshell thingies.
Link Posted: 4/13/2006 4:52:14 AM EST
Thank you for the answers. I know the concern for leaving marks on what many on this forum consider "Tools of the trade" does not matter. I appreciate the responses with the lack of flame!

Gunzer
Link Posted: 4/13/2006 8:18:31 AM EST

Originally Posted By ar-wrench:
Boresighting is not possible with the clamshell thingies.



I have the Bushmaster block. I’ve never bore sighted my weapons before, but why couldn’t a guy bore sight with the BM block? It doesn’t obstruct the top of the receiver.

Link Posted: 4/13/2006 4:14:58 PM EST

Originally Posted By QUIB:

Originally Posted By ar-wrench:
Boresighting is not possible with the clamshell thingies.



I have the Bushmaster block. I’ve never bore sighted my weapons before, but why couldn’t a guy bore sight with the BM block? It doesn’t obstruct the top of the receiver.




Every clamshell setup I have seen has a receiver insert (fits in the carrier cavity) to keep from crushing the receiver when tightened down. You can not boresight with something in the breech as you tighten.
Link Posted: 4/14/2006 12:06:39 AM EST

Originally Posted By ar-wrench:
Every clamshell setup I have seen has a receiver insert (fits in the carrier cavity) to keep from crushing the receiver when tightened down. You can not boresight with something in the breech as you tighten.




The BM block does not utilize an insert so I guess it would work.

Link Posted: 4/16/2006 1:56:15 PM EST
To prevent those "Shiney Marks" on your Upper Receiver when you are useing the Wrap around Action Block, I use a a Zip Lock style heavy Freezer Bag. I wrap the receiver with the bag before I put it in the Action Block. You will not get those "Shiney Marks" than, which are caused by the Action Block rubbing on your Upper Receiver.
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