Low Reciprocating Mass Build

[jtallen83]

I'm putting the final touches on my latest build, a Matrix receiver set, 14.7 inch pencil barrel, SLR adjustable gas block and a d. wilson lightweight BCG. I've ordered an enhanced carbine spring from Taccom.

http://www.taccom3g.com/enhanced-carbine-spring.html

One of my last decisions is to run a buffer with the weights removed, leave them in, or get the lightweight set-up from Taccom that is basically a two part weightless buffer

http://www.taccom3g.com/carbine-recoil-system.html

Question, is anyone here running anything like this? I've found a few threads on barfcom that claim all the 3-gun guys are running a light buffer with adjustable gas block and having good results with very little muzzle movement and good recoil reduction

Edited March 29, 2016 by jtallen83
title change

[guruofhotrod]

This caught my attention, is this what you're considering?  I'm not sure how well it works, I'd say it's worth looking into.

http://slrrifleworks.com/index.php?route=product/product&path=57_103_104&product_id=393

Edited January 1, 2016 by guruofhotrod

[jtallen83]

Yep, that started me thinking. SLR gets it from Taccom3g where I picked up the buffer spring. It appears there would only be a bit over an ounce difference if I just remove the weights from a carbine buffer instead of buying the plastic plugs from Taccom3g. Hope to put something together for the wife and grandkids that shoots real soft and is nice and light. Haven't test fired yet but had them all hold the rifle and operate the controls. Biggest complaint is the balance is nose heavy but I don't see where I can lighten it anymore. I'm hoping a Beachin sling used properly will help them overcome the nose heavy balance issue rather than add weight to the stock.

Here is a link for Taccom3g recoil management products;

http://www.taccom3g.com/ar15-components.html

Edited January 1, 2016 by jtallen83
added link

[guruofhotrod]

What handuard/rail are you using - the matrix stuff that Chris Riedeman has is pretty darn light and the O.D. is smaller than many

other models which would be a plus for many women and youngsters that have smaller hands. I haven't seen them on Chris' site

But I'm sure he could get them:

http://www.matrix-arms.com/product/lavi-15-5-handguard/

I think I recall you mentioning that you already have a pencil profile barrel so the only other thing would be a lightweight gasblock

like the titanium SLR models or if that's not in the budget you may be able to find an adjustable aluminum gasblock (actually lighter

than titanium but, I always worry about aluminum's thermal characteristics allowing it to expand more and faster than the barrel possibly

resulting in it loosening and/or leaking when it gets hot. Same thing with an aluminum muzzle device - probably would have to be pinned.

 

 

[jtallen83]

I got the rail in the set from Chris.

http://www.centralfloridafirearms.com/product/cerakoted-fde-ar15-receiver-set/

I had thought about a shorter rail but for the price of the set figured I could sell the rail if I didn't like it, that's not happening though, I like it! Only downside is now I have to invest in keymod gear for it.

Went with the regular SLR adjustable, titanium was too pricey and shiny for my taste, plus I'd hate to compete with breastguy for most anal lightweight parts buyer ;-)

Pinned a standard flash hider on the 14.7 inch barrel, the comp I had was just a hair short of the 16 needed, kinda glad I went that way now, trading the minimal recoil reduction away is balanced by the lack of concussion felt.

I think I'll yank the buffer weights tonight and hope for a decent day to test fire, range is pretty well snowed in right now.........

[jtallen83]

I put the enhanced spring in and took the weights out of a buffer. No test fire going to happen in this weather but I tried cycling some rounds by hand. First thing I noticed was a much louder "sproing" noise. It also has issues stripping every third or so round from the magazine. The bullet gets stuck on the feed ramps between lugs, pull back the carrier and let it go and they chamber. I tried it with a regular weight buffer and got the same thing. Put the standard spring and buffer in, same issue but the bullets get set back more often and further than with the enhanced spring. Tried the test with a P-mag, Lancer mag, and a metal mag, all the same results. Looks like I'll need to do a little research on ramp polishing..........I don't own a Dremel.....yet.

[jtallen83]

OK changed the thread title as it looks like I put the cart before the horse. I seem to have an issue with the feed ramps on my Ballistic Advantage 14.7 in pencil barrel. As I described above it doesn't matter what buffer/spring configuration or what magazine I use the bullets catch, are gouged, or set back by the edges of the ramp. It does the same thing on both sides. I'll add pictures below.

Before I go filing and buffing on the extension is there other tests or issues I should be looking at?

I had always understood that the ramp should be deflecting the bullet to the center of the chamber rather than the bullet sliding along the ramp? It is hard to see but the bullet tips are hitting just past the beginning of the steel portion of the ramp and leaving a mark right up the middle of both ramps. I see no evidence of the tips hitting on the aluminium portion of the ramps. The edges around the lug cuts are sharp but I don't feel any burrs when I run a pick across them.

What next guys??????

[washguy]

The cure for your ramp prob is lift up the front end and rear of the mag lips a tad so the angle of the bullet is upwards.....lemme go see if i can find the pics you can do it with the mag spring too...oh and you cant do that with the plastic pmag...well you can but its dremel time....so this isnt the greatest pic...ill go find the best one.....but the bullets were hitting the feedramp too low....so you tweak the lips of the mag very lightly...both lips...ive got the lip tweaker tool from brownells.....so now the nose of the bullet is in a better attitude to the ramps...use the pdf  to see what you need

Wash

Mag-Feed-Lip-Tweak-4.pdf

Edited January 3, 2016 by washguy

[jtallen83]

I might just have an old sheet metal tool that would work to bend the lips but keep them straight. If it works then I'll grind on a Troy battle mag as well. I like that better than grinding away metal on the extension. I wouldn't usually be content with a rifle that needed a special mag but this one will just be a range gun so no big deal.

Still has me puzzled why they hit so low on this rig. I might try swapping some lowers tomorrow and then take some measurements to see if the magazine is in a different position than my other rifles.

Thanks for the tip!

[washguy]

yes some lowers are different in mag height areas    where the mag locks in in relationship to the height of the lower  

heres another mag tweaked.....i dont want my bullet tips smacking  on the ramps too much     Wash

Edited January 3, 2016 by washguy

[survivalshop]

 Relieve your Upper Receiver where the Barrel Extension ramps meet the Upper Receiver , it can be done with a small rat tail round file & being careful not to jam the point of the file into the Chamber or a small stone or sanding drum in a Dremel tool , to make sure the ramp is continuous into the Upper Receiver & flow into the Barrels Extension feed ramps .

  Bending feed lips is good for the Steel mag's , what about the plastic ones ? 

  Are you sure the Bolt is stripping the fresh round from the Mag ? & not the Bolt Carrier  or in-between ? If the BC grabs or shoves the fresh round , they will almost always nose dive into the feed ramps.

 Are you sure your Mag catch is set correctly ?

 You say this issue happens with any Buffing system you try , does this mean the Receiver extension has been swapped out to test a different one ?

    I'm not one for light weight Buffer or BCG systems or adj. gas systems , to me its just looking for added issues . If anything , get them broke in with std components & then once the rifle is broken in & barrel is seasoned ( if needed ), then you can swap out different components , one at a time , to set them up & test function. 

 

[jtallen83]

    Spent a couple hours playing with this build. Checked out many of the suggestions above. Broke down all my AR-15's and started looking and swapping. Magazines sit the same in all the lowers. Put the lower on my Sig upper, no issues. Tried to put my Armalite upper on the lower but the barrel nut is too close to the hinge pin or the Matrix hinge is too big so no go there. Put a Spikes lower on the Matrix upper got some rounds hanging up as before but only when I rode the charging handle forward slowly. Tried the Sig lower and got the same.

    Got out a magnifying glass and light for a close look at the ramps and changed to a pointed pick, found there are some slight burrs along the edges of the ramp cuts. Got out my needle file set and started filing. I found that the QPQ extension is some hard ass chit, no worry about taking too much in one stroke! It became evident that the edges around the lug cuts and the lower part of the ramp were high spots as they got shiny while the center of the ramp still had copper marks from the bullets. I stopped when the pick quit catching on the edges.

Put things back together and ran through the same combinations of the Matrix upper on my lowers. Progress, I hope.....

 The Sig and Spikes lower combinations had no hang-ups. The Matrix lower only hung up twice and that was with the low power spring when riding the charging handle forward slowly. The full power spring in the Matrix worked fine. Looks like I'll invest in a dremel next and do some polishing before any live fire function test.

I'm set on making this low mass combination work, no turning back now!

[jtallen83]

Finally got this rifle test fired. Once I got the gas adjusted there were no malfunctions with any of my mags. Running the buffer with no weights, the "enhanced" spring that has 10% less strength, 4 clicks open on the SLR gas block(5-6 clicks for cheap .223), and the d wilson lightweight BCG. A nice soft shooter just like I'd hoped for. The 8 year old granddaughter sent 15 rounds down range and pronounced it a "good gun", made grandpa smile!

Edited April 1, 2016 by jtallen83
correct the numbers

[washguy]

JT    Well done !      Wash

[jtallen83]

Pictures;

Finished product, for now anyway. 
Matrix receiver set and rail
Ballistic Advantage 14.7 inch pencil barrel
d. wilson lightweight BCG
SLR adjustable gas block
Taccom reduced power spring
Weights removed from a standard carbine buffer
Mech Armor TacOps I charging handle
Strike Industries for all the small parts, grip, and stock
Vortex Strikefire red/green dot
Streamlight TLR1
Weighs in at 6 pounds 8 ounces like you see it in the pictures.
Still waiting for the BUIS I want to be in stock.

[shepp]

That's a sexy rifle you got there sir

[slugger43]

8-year old granddaughter at the range with grandpa?  Absolutely wonderful!  As a grandfather, that's my idea of "girls with guns".  Congrats!

[survivalshop]

  Nice , persistence pays off .

[jtallen83]

Put a PA 4-16x scope on the rifle today and got easy 1.5 MOA groups from my local Iowa ranges lousy bench in 30-35 mph winds with Perfecta 55 gr. ammo. I think with better conditions and ammo it will be a 1 MOA rifle.

[unforgiven]

Good job on that rifle brother,like the look.

[sketch]

nice rig bro!  for an 8 year old.. 

[jtallen83]

The granddaughter would have prefered the my little pony theme but it's actually the wife's rifle and she insisted it match her MK25D. I got some of the ideas from Breaststroker so it truly is a girly gun. ;-)

[planeflyer21]

Bwwaaaahahahahahahahahahahaha!!!

[blue109]

That stock looks pretty cool! Never seen that one before

[jtallen83]

It will be for sale soon! It has a very sloppy fit both on the tube and the pin. I had to add grip tape to the butt because it was slicker than snot. They're going to come out with a butt pad soon but unless they solve the wobble issues I won't mess with one again, going back to a Magpul on it soon.