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Posted: 7/31/2004 9:32:40 PM EDT
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Does anyone know if the Yankee Hill LW FF forearms top rail is even with the upper receivers rail? And is the spacing right so something could bridge the gap between the two? And also, does A.R.M.S. or someone make a Swan sleeve type deal that would tie the forearm and the receiver together? TIA,AL |
Yes, yes & yes Top rail is even with the receiver. I was able to install an ARMS 38S-EX-MOD onto a LWFF, but the installation could not be completed because the slots didn't line up:  I have bridge the gap with single piece scope mounts and carry handles. That is how I keep the tube indexed to the receiver when I tighten the tube's locknut:  Rock River makes a continuous rail for these tubes (Rock River & YHM are the same tubes): 
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The slot spacing wasn't right for the ARMS 38S-Ex-Mod. but is for the Rock River deal? Not quite following you there. I'm not real comfortable with mounting a scope to the FF tube and am wondering if you tied the tube to the upper receiver rail with a rail or sleeve, it wouldn't make it a little more solid. Any chance of sticking the LW-FF Tube or locknut in a lathe and changing the spacing of the cross slots? Thanks for the help, life would be a lot easier if I could get my paws on these parts and look them over first hand.  AL |
Can't tell for sure by the pics, but you might (might?) be able change the spacing of the rails on the FF tube (in compairison to the distance from the flat top upper), by spinning the YHM "Jam" nut (used for indexing), to extend the FF forward. |
You would think that, but this is how much (or little) room you have to move it forward. A rough measurement showed that the gap between the tube and FSB was too small to make up the difference.  As far as taking the tube to a lathe, you probably could make the spacing anything you wanted by shaving either the locknut, tube or both. I did this experiment awhile ago for a couple of reasons 1. To see if the FF tube top rail was level with the receiver - it is. 2. To see if the ARMS 38S-EX-MOD rail could be used with the YHM/Rock River/BMAS rail systems - it likely can't without some mods. The ARMS 38S-EX-MOD was made to specifically fit the KAC RAS system, so it was not completely suprising that it didn't fit other systems.
I've seen the Rock River rails installed and it does work. Can't find the thread or pic, guess you would just have to take my word for it. |
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the 2 FF handguards I have from YHM(Carbine length, and removeable railed rifle forearm) both are the same level as the upper receiver. However, they are not milspec on the bottom of the rails, so an ARMS riser may not slide across from the upper on to the forearms. |
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Slightly off topic, but I tried the same test with a YHM removable RAS, similiar to the KAC RAS with the same basic result. See my pics at the bottom of the review. YHM Carbine RAS Review |
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