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  #1  
Old 05-26-2020, 11:27 AM
Tom in AZ Tom in AZ is offline
 
Join Date: Aug 2010
Location: Arizona
Posts: 20
Default Magpul UBR Gen 1 buffer and spring in service rifle.

This year my service rifle is sporting a new WOA flat top receiver with Geissele MK7 quadrail and a Krieger 1:7.7 barrel harvested from my old A2 receiver. My optic, currently, is an old Trijicon TA31F with red chevron and I will decide on optics after shooting a couple matches, suggestions welcome. My lower is a Stag Arms. I will install a Geissele 2-stage SSA trigger and Magpul UBR Gen 1 stock next week. My question, can I use the rifle-length/weight standard buffer and spring from the existing A2 stock or must I switch to a carbine buffer and spring and, if so, which weight and spring? Thanks very much, hold hard. - T.
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  #2  
Old 05-27-2020, 12:06 PM
TomH TomH is offline
 
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Yes, you will need a carbine buffer and spring. As far as what spring...it depends on what weight bolt carrier, what your load is, etc. You'll probably just have to get one and try it. See if the bolt locks back consistently, if not try something different. Not very scientific but usually how it goes.
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Old 05-27-2020, 12:19 PM
Tom in AZ Tom in AZ is offline
 
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Thank you!
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Old 05-30-2020, 01:20 AM
HighpowerRifleBrony HighpowerRifleBrony is offline
 
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Location: Texas
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Quote:
Originally Posted by Tom in AZ View Post
This year my service rifle is sporting a new WOA flat top receiver with Geissele MK7 quadrail and a Krieger 1:7.7 barrel harvested from my old A2 receiver. My optic, currently, is an old Trijicon TA31F with red chevron and I will decide on optics after shooting a couple matches, suggestions welcome. My lower is a Stag Arms. I will install a Geissele 2-stage SSA trigger and Magpul UBR Gen 1 stock next week. My question, can I use the rifle-length/weight standard buffer and spring from the existing A2 stock or must I switch to a carbine buffer and spring and, if so, which weight and spring? Thanks very much, hold hard. - T.

A warm load behind the 60gr TMK to equal 3000fps shall follow the entire BDC precisely. Otherwise with 75/77gr, zero a minute or so high at 100yds to matchup 300 and 600.

Standard carbine spring. A standard carbine buffer shall function fine, but an H2 should ease the yank on the case. An H3 might be too much, depending on port diameter and tube/key fit.
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  #5  
Old 06-02-2020, 08:39 AM
mike miller mike miller is offline
 
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I would rethink my trigger selection and go with the Geissele 2-stage NM trigger. Itís adjustable for weight whereas the SSA is not.
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  #6  
Old 06-02-2020, 10:39 AM
canes7 canes7 is offline
 
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Location: Raleigh, NC
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I have a similar setup as the OP. With a full weight carrier I ended up with the H2 weight buffer. The H3 worked mostly but the H2 was 100% reliable and the recoil felt perfect. My loads are 80.5’s and 77’s loaded just a little hot, not much.
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Old 06-10-2020, 09:04 AM
Tom in AZ Tom in AZ is offline
 
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Location: Arizona
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Thanks again for the advice and guidance. H2 buffer with Springco white buffer spring is installed. The Geissele 2-stage SSA will have to stay until I can fund a NM trigger. The rail ribs are pretty sharp so a set of Ergo ladder rail covers is next.
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  #8  
Old 06-15-2020, 12:20 PM
TomH TomH is offline
 
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The trigger you have will be 100x better than a GI style trigger.
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