Are the DPMS ones the correct dimensions?

How good does this design work compared to a birdcage?

The DPMS three prong is a very good reproduction part.  I'm uncertain of it's capabilities as a flash hider compared to the bird cage.

I had seen an article in the original  SWAT magazine in the 1980s comparing the 3 prong with the birdcage.  THe high speed, low light photos showed the 3 prong much more effective.  Years ago I had an original duckbill 3 prong (wish I had it now) and fired it at dusk-dark.  The was virtually no visible flash to speak of.

Three prong works better but is not as sturdy as a birdcage.  DPMS is probably as good as any if you can't find USGI.  The USGI have become hard to find for decent price.

The reason they got rid of the three prong is because it got snagged in the bush in Vietnam.  The bird cage was suppose to stop that from happening.  Except for that little flaw the three prong was a much better flash hider.

I heard they work really well besides the grass thing. I wondered how well they work on an SBR but what flash hider doesn't turn into a flame thrower on a -10.5 ?

I am just putting one of these on an SP-1 upper I am building with mostly aftermarket parts for a shooter. I have a nice brand new bird cage from Apex for my true 604. The complete stock set I got from them was immaculate also.

I did an informal study  on muzzle flash. I found that the powder you used was far more relevant than the muzzle device you use.

I concur.

+100

WA-Tom,  Mind telling me what is the best powder to use in your opinion.  Don't really care about flash but it could be revelant.  The  bullets I have (.224) are 55gr FMJBT,  69gr Hornady BTHP and 75 GR BT A-Max.  I have 1-7, 1-8, 1-9 and 1-12 twist barrels.  Probably should post in re-loading but anyone who would do extensive testing on muzzle flash is worth listening to.  I've just been using up what powder I had on hand getting pretty old and need to buy more soon.  Down to a four lbs of Hogdon H4895 and H335.  Many say Varget is GTG.  Guessing different powder for lighter and heavier bullets.  Been out of the loop for a while.  Anyone else feel free to speak up.  Got lots of LC once fired and small rifle primers.  Didn't mean to jack.  Apologies.

Regretably I didn't save any information. I can say that from a reloaders standpoint I would use a faster burning powder so that it does not spit unburned powder out in front of the muzzle, thats what really causes muzzle flash. Find a good powder and a good hider and your set. I personally never really cared much about how much flash I had but a couple things caused me to look into it.  A LEO customer wanted some supporting data to back his request for suppressors for his entry team and the other was simply to get intormation about why we should be allowed flash hiders during the AW prohibition.