New PCC with feeding problem......

[MikieM]

2 hours ago, Aircooled6racer said:

Hello: I am using QC10 parts also but I have used Faxon, JP,  KAK and Wilson Arms barrels with success after I chamfered some of them and put a radius on them. Tim at Taccom should fix you up. Thanks, Eric

 

I agree.

[M&P]

Had the same issue. And seen it a few times now in others guns.  Increasing the radius on the bottom of the barrel can help but ultimately I found the bolt is the issue.  People are trimming the bottom of the bolt back to fit ramped barrels.  But not putting the radius back on so the round can slide up the bolt face.  Mine would catch on the bolt face right on the corner by the extractor.  Just my 2 cents

[MikieM]

2 hours ago, M&P said:

Had the same issue. And seen it a few times now in others guns.  Increasing the radius on the bottom of the barrel can help but ultimately I found the bolt is the issue.  People are trimming the bottom of the bolt back to fit ramped barrels.  But not putting the radius back on so the round can slide up the bolt face.  Mine would catch on the bolt face right on the corner by the extractor.  Just my 2 cents

 

It's hard for me to see what you did to remedy the problem. Could you explain further?

Thanks, Mike.

[L9X25]

I am betting he means the part below the extractor, that can stop the case  from sliding under the extractor easily.  Looks like he polished that back a little.

 

[MikieM]

34 minutes ago, L9X25 said:

I am betting he means the part below the extractor, that can stop the case  from sliding under the extractor easily.  Looks like he polished that back a little.

 

 

On my QC 10 bolt, and I think JP is the same way, the lug at the bottom has been cut back by about 40 thousands to accommodate a ramped barrel.  

[M&P]

Yes mine started to fail in that area when the bolt was trimmed back .040" because the radius on the bottom lug of the bolt is removed and  mikiem is correct the area right by the extractor has been the main problem in 3 of them now.   Compare the shiney radius area in the picture to your bolt and you should see the difference.

[Aircooled6racer]

Hello: I still think it is a barrel problem not a bolt problem. Thanks, Eric

[Timido]

I don't think the original  poster has the ramped barrel.  

[MikieM]

2 hours ago, Aircooled6racer said:

Hello: I still think it is a barrel problem not a bolt problem. Thanks, Eric

 

Correct. My view, and Tim Ubl's view as well, is the non-ramped barrel isn't working as well as it should with my set-up. I have a Taccom ramped barrel ordered.

1 hour ago, Timido said:

I don't think the original  poster has the ramped barrel.  

 

That is correct. I don't.

[Flatland Shooter]

1 hour ago, MikieM said:

 My view, and Tim Ubl's view as well, is the non-ramped barrel isn't working as well as it should with my set-up.

 

Any explanation why?   Is it a problem using an unramped barrel with a bolt that's cut for a ramped barrel?

[MikieM]

2 hours ago, Flatland Shooter said:

 

Any explanation why?   Is it a problem using an unramped barrel with a bolt that's cut for a ramped barrel?

 

Still unknown until Tim get's the old barrel back. 

A bolt that's been cut back 40 thousandths to accommodate a ramp will work with both ramped and non-ramped barrels. 

I'm thinking the edge if the chamber is too sharp and the round is simply hanging up at that point and not allowing the round to slide up the bolt face as it closes.

We should know by the end of next week. 

Stay tuned.............

[L9X25]

IMO, once the projectile finds it's way into the chamber, the ramp (or lack of ramp) is irrelevant.  The ramp only helps a low projectile slide up into the chamber.

Based on your description, and pictures, your projectiles are finding their way into the chamber just fine.    

 

I am not saying that the new barrel will not solve the problem, but the lack of ramp is not causing the problem that you are experiencing.

We either have a sharp edge at the bottom of the transition into the chamber, or an issue with the bolt face. 

 

If you were to gently let the bolt down on a dummy round, and let it jam the usual way, then gently press the head-stamp away from the extractor with a popsicle stick you would likely get your answer.  If the bolt closes, it is the alignment boss below the extractor, if not, it is the transition into the chamber.

[MikieM]

1 hour ago, L9X25 said:

IMO, once the projectile finds it's way into the chamber, the ramp (or lack of ramp) is irrelevant.  The ramp only helps a low projectile slide up into the chamber.

Based on your description, and pictures, your projectiles are finding their way into the chamber just fine.    

 

I am not saying that the new barrel will not solve the problem, but the lack of ramp is not causing the problem that you are experiencing.

We either have a sharp edge at the bottom of the transition into the chamber, or an issue with the bolt face. 

 

If you were to gently let the bolt down on a dummy round, and let it jam the usual way, then gently press the head-stamp away from the extractor with a popsicle stick you would likely get your answer.  If the bolt closes, it is the alignment boss below the extractor, if not, it is the transition into the chamber.

 

Tell me what you think of this. At the moment I have the barrel off the gun so I took a loaded round and tried every way I could to stick the round at the chamber mouth (holding the barrel in one hand and the round in the other), and I couldn't. Shallow angle, steep angle, very steep angle, it didn't matter. The round would go into the chamber as easy as pie.

Now I'm thinking bolt again. Where's Jim Beam when you need him? 

Edited October 8, 2017 by MikieM

[L9X25]

If you have any of the rounds that jammed nearby, you might carefully inspect the outer rim of the brass and see if you can find any marks from where they snagged on the bolt.  

 

The boss below the extractor has a purpose, but it can also cause a snag if it protrudes too far. 

 

 

 

[MikieM]

URETHRA!!!!!!

My new gun is running like a German train schedule. Just got back from the range and can report no problems what-so-ever after 200 rounds.

What did I do, you ask? Two things. First I installed a Taccom BCG. Not only does it work great, but it looks great as well. And, it is also almost 2 ounces lighter than the other bolt. 

Second, I took out the 308 plunger spring and put back a common 5.56 AR spring. Remember that the Taccom barrel is only 5.25 inches long (the rest being a shroud) so the power factor is going to be like that of a pistol. About 130-ish. This isn't (in my view) enough power to cycle a heavy bolt correctly. I have since ordered a spring that is recommended for barrels of 4 to 6 inches, and will be giving that a try soon.

Onward and upward.

 

A special thank you goes out to Tim Ubl, for all his help, and to the guys at Quarter Circle 10, for their's. Two great companies who will go a long way in our sport.

Edited October 13, 2017 by MikieM

[nickbfishn]

40 minutes ago, MikieM said:

URETHRA!!!!!!

My new gun is running like a German train schedule. Just got back from the range and can report no problems what-so-ever after 200 rounds.

What did I do, you ask? Two things. First I installed a Taccom BCG. Not only does it work great, but it looks great as well. And, it is also almost 2 ounces lighter than the other bolt. 

Second, I took out the 308 plunger spring and put back a common 5.56 AR spring. Remember that the Taccom barrel is only 5.25 inches long (the rest being a shroud) so the power factor is going to be like that of a pistol. About 130-ish. This isn't (in my view) enough power to cycle a heavy bolt correctly. I have since ordered a spring that is recommended for barrels of 4 to 6 inches, and will be giving that a try soon.

Onward and upward.

 

A special thank you goes out to Tim Ubl, for all his help, and to the guys at Quarter Circle 10, for their's. Two great companies who will go along way in our sport.

Excellent news!Excellent news!

[tyler2you]

50 minutes ago, MikieM said:

URETHRA!!!!!!

 

Please tell me no parts of your carbine got near your Urethra 

[MikieM]

Did I say Urethra? I meant Eureka!

At my age I sometimes get confused. Urethra is my second cousin twice removed. 

[gdcguns]

What happens on the range, stays on the range......

1 hour ago, tyler2you said:

 

Please tell me no parts of your carbine got near your Urethra 

 

[Aircooled6racer]

1 hour ago, gdcguns said:

What happens on the range, stays on the range......

 

Hello: And hopefully in your pants! Thanks, Eric

[noexcuses]

On 10/7/2017 at 4:34 PM, M&P said:

Had the same issue. And seen it a few times now in others guns.  Increasing the radius on the bottom of the barrel can help but ultimately I found the bolt is the issue.  People are trimming the bottom of the bolt back to fit ramped barrels.  But not putting the radius back on so the round can slide up the bolt face.  Mine would catch on the bolt face right on the corner by the extractor.  Just my 2 cents

thanks for this, was having the exact same problem. Had issues after running out of round nose bullets and going to TC bullets. The TC bullets were not making it into the barrel, deadheading below the "ramp" in a nonramped barrel before they were in.  swapped in Taccoms ULW ramped barrel and was still having problems, they were hanging up in the barrel, but only with 31 round glock mags. Made the modification to the bolt face like above and it seems to be great. Have just tried running this by hand only and have not gotten it to the range.

[Flatland Shooter]

On 10/8/2017 at 9:24 AM, M&P said:

Yes mine started to fail in that area when the bolt was trimmed back .040" because the radius on the bottom lug of the bolt is removed and  mikiem is correct the area right by the extractor has been the main problem in 3 of them now.   Compare the shiney radius area in the picture to your bolt and you should see the difference.

 

What tools were used to cut back and radius the bolt?  Is it time to break out the Dremel tool?

Edited October 28, 2017 by Flatland Shooter

[noexcuses]

5 minutes ago, Flatland Shooter said:

 

What tools were used to cut back and radius the bolt?  Is it time to break out the Dremel tool?

that is what I used

[M&P]

The radius to round the edge was simply a dremel with a stone to break the edge.  Then polishing with dremel to clean up the radius without going to far to fast. 

[1911A12]

`1aqW