The Tale of Two Uppers

[Bang!]

Recently ordered two 6.5 Grendle uppers. In the picture from left to right: one unfired round, two cases from upper number one, two cases from upper number two. Hornady Black 123 gr ELD MATCH #81528 factory ammunition.

Supplier of uppers to remain nameless until I've worked thru this and some other issues with them.

Upper number one doesn't extract brass. Have to pull down on charging handle and mortar weapon to extract brass.

Upper number two extracts but has similar marks on case and bending of rim from extractor.

Both uppers were cleaned well prior to test firing. I don't have a chamber brush but I did clean chambers with old chamber mop covered with a Rem Oil soaked patch. Seemed to fit just snug enough to clean well. Chamber and bore were cleaned until patches came out white. Cotton swabs, pipe cleaners, ..... Usual process for me with any new firearm.

Chamber mop used is one from Hoppes, "Cotton Swab". Also used the Rem Oil to spray (hose) out chamber.

Is there something further I can do here? Is this just a dirty chamber and I need a chamber brush of some kind? Or is this something that needs to go back to manufacturer.

Thanks

 

[Blue68f100]

So it indicates that the brass is trying to be extracted under too much high of pressure. Need to slow the bolt velocity down. Do they have an adj gas block. What length gas system? Are you using a heavy damper, full bolt or lightened. Are there any over pressure signs on the brass base, ejector imprint....

 

[Bang!]

That makes sense.

Gas block is not adjustable. Mid length gas system. Bolt appears same as my other bolts.

No high pressure signs; primers are rounded, no ejector marks.

Fired both of them on a PSA lower that came as a complete weapon with mid length gas. Buffer assembly weighs in at 2.95 oz.

PM inbound.

 

[boom boom]

Take a led trouble light and try to get a good look at the chambers. Failure to extract can also be caused by a rough chamber that grabs the brass making extraction difficult. Otherwise what blue68 said could be a problem in that your bolt is trying to extract while the pressure is still to high in the chamber. Need to slow down the cyclic rate in that case through a heavier buffer, an auto bolt carrier, etc. An adjustable gas block works and I do believe there is a gas key that adjusts gas intake as well but don't know how that works. Easiest is a heavier buffer or m16 bolt carrier.

 

[Bang!]

The gas makes sense. But, upper number one doesn't extract at all. Have to mortar the spent brass out. Is this a fast bolt symptom, too?

Tried to look in chambers. Just can't get a good enough angle. Rough chambers was my first thought.

 

[ponchh]

I ran into a barrel that had some of the same problems. Patch's would be clean ect. Turns out there was a coating of something that acted like baked on lacquer. Soaked over night in lacquer thinner then worked it with a bore brush. Did that 3 times to get it all out. Probably not your problem, but it's something to check.

 

[boom boom]

A cheap way is to check chambers is to buy a borescope 720p resolution or so from ebay or Amazon that connects to your computer or smartphone. Less than $30 and useful enough to check chambers and depending on which model you get barrels and throats. Prices vary by attachments such as angled mirrors, and head size (smaller usually costs more or has poorer resolution).


Yes, failure to extract at all in your upper could be caused by a too fast cycling rate. Simply the brass is still expanded to the chamber walls from high chamber pressure when the extractor is trying to yank it from the chamber. Slowing the bolt allows the chamber pressure to recede to an acceptable degree to extract the fired cartridge. In a bolt action, you can never get that fast but in a semi auto you can too fast or even too slow which can cause problems. Just curious, what kind of mags are you using? Grendel specific mags are generally recommended (from my understanding the followers are somewhat different) and that could be your problem or your uppers don't like those particular Grendel mags. Sometimes certain mags can interfere with the bolt speed as well.

This can also happen with ammo as well--a too tight match type chamber can be problematic with blaster grade ammo which varies more in its quality control resulting in problems. If you have the ability to check your ammo with calipers do so. You might want to get some premium ammo to fire as well in that problematic upper.

 

[Bang!]

Tested both uppers this morning with an H2 buffer. Used two different lowers and different buffer springs. No change. Contacted supplier for refund. They're wanting to add numerous charges for returning. I pay for shipping, original 3% for debit card use, 3% for refund to debit card, and their site has 12% restocking fee. My opinion; not receiving functioning uppers calls for their loss, not mine. This company doesn't have any reviews to speak of online. Guess I was the guinea (sp) pig. We'll see.

 

[boom boom]

Tested both uppers this morning with an H2 buffer. Used two different lowers and different buffer springs. No change. Contacted supplier for refund. They're wanting to add numerous charges for returning. I pay for shipping, original 3% for debit card use, 3% for refund to debit card, and their site has 12% restocking fee. My opinion; not receiving functioning uppers calls for their loss, not mine. This company doesn't have any reviews to speak of online. Guess I was the guinea (sp) pig. We'll see.

I agree you went the extra yard. Returning it for what you can get is probably the best way out of a hassle.

 

[Hokie_PhD]

Tested both uppers this morning with an H2 buffer. Used two different lowers and different buffer springs. No change. Contacted supplier for refund. They're wanting to add numerous charges for returning. I pay for shipping, original 3% for debit card use, 3% for refund to debit card, and their site has 12% restocking fee. My opinion; not receiving functioning uppers calls for their loss, not mine. This company doesn't have any reviews to speak of online. Guess I was the guinea (sp) pig. We'll see.

I'd call them
I'd make it clear that I expect the, to make good. I'm fine with paying restocking charges if I'm at fault. But if a product is defective I'll fight until they either give me a full refund or a suitable replacement.

As a last resort, Let them know you'll say good things about them if they treat you right, but will share your bad experience if they don't. Small and new companies can't afford a bad reputation. Hell, big ones can't either. So here's hoping they'll help you get this right.