01-30-2023, 03:48 AM
montana Wrote:Explain won't feed rounds from magazine.
Bolt carrier does not go back far enough to pick up rounds from magazine or to engage bolt stop. Engages on bolt carrier front rather than bolt. Pulling charging handle back allows bolt to pickup fresh round from magazine.
Are you able to chamber a round and eject it by hand with out a problem?
Can chamber and eject rounds by hand using charging handle fine. Rifle fires and ejects spent case.
What type of barrel and bolt do you have?
This was a complete upper from well known company. Bore scoped barrel before shooting, looks very good throughout.
Does your upper fit the lower OK?
Upper fits lower perfectly, no binding anywhere.
Does the barrel feed ramps look OK in the upper?
Feed ramps not an issue, feeds perfectly using charging handle.
What type of magazine are you using?
Used both AA Elander and Duramags, no difference.
Is the gas tube old-new-fit the gas key properly?
Complete new upper and parts, tube not rubbing on key.
The Colt carrier was an older anti full auto type to prevent the rifle from tripping an auto sear.. Did you try using both lowers on your Grendel upper?
Did not try other lower. Upper returned to vendor and saw video of smith shooting it on their lower. Problem seems to be the difference in the BC weight. I will have to try it with the Colt supplied BC that weighs less. Then will try supplied auto BC with 556 upper to see it it functions there.
Bolt just not coming back far enough to catch bolt stop or to go back far enough to get behind rounds loaded in mag.
Need more info..
Answers to questions inserted in your post.
Smith believes Colt lower is the issue. If needed, I guess I'll have to build a lower comparable to the one the smith used.