Personal experience with helical springs??

[roundball]

I'm not a builder, but if anybody has actual hands on experience with the folloiwng, I suspect it might be someone who frequents this 'builder's catagory.

The good news is that the .40cal GM Flint barrel I had ordered was on the front porch when I got home tonight.

The bad news is it looks like they screwed up the touchhole...drilled it out too large, then tried to make it work by putting a helical spring into it, then screwing the vent liner into the helical spring.

Looks like a rube-goldberg set up and I'm scared to shoot it...my inclination is to insist that they take it back.

Is this helical spring thing a legimate build step?

Is is safe?

Would you keep it or return it?

Thanks

 

[bob1961]

send it back and make them do it right....i've had those coils go bad on alot of applications not even close to the pressure that will be in a gun barrel............bob

 

[AeroncaTAL]

I've run across helicoils on the aircraft that I've owned, when the threads on the aluminum heads strip out for the spark plugs or the cylinder head hold down bolts. They work and will take the torque on a bolt, but eventually the coils will back out. When that happens you usually have to drill and tap for a larger coil. I imagine that you could probably shoot it, but personally I'd send it back.
Scott

 

[spitfire]

Send it back for correction.

 

[Birddog6]

Yes, that is a Helicoil repair. :nono: Send it back. No way I would accept that. They should have went to a larger vent size.

 

[roundball]

Yes, that is a Helicoil repair. :nono: Send it back. No way I would accept that. They should have went to a larger vent size.

Thanks all...exactly how I felt about the situation, but wanted some feedback just to be sure I wasn't being an old maid... :grin:
:thumbsup:

 

[roundball]

Yes, that is a Helicoil repair. :nono: Send it back. No way I would accept that. They should have went to a larger vent size.

Thanks all...exactly how I felt about the situation, but wanted some feedback just to be sure I wasn't being an old maid... :grin:
:thumbsup:

UPDATE
Just got of the phone with Rick Sanborn, GM plant manager...he was personally aware of the problem and did agree to send me a prepaid UPS shipping label.

However, he indicated if I sent it back it would be well over a year before they'd be ready to make any more using normal "cut thread" plugs.

The problem is that they went to a "roll cut" process a couple years ago, which resulted in that big barrel recall they had (ie: my .58cal Flint barrel had to have it's plug changed)...and they used up all the "cut thread" plugs they had on hand in the recall.

That left them with an inventory of "roll cut" plugs which they decided to rework with helicoils rather than scrap them...both cap and flint. Told me the helicoil is actually stronger.

I thanked him, but reiterated I was returning the barrel and if I couldn't get a 1st quality .40cal barrel, then I wouldn't get one at all. He replied that he'd have some folks rummage around through stock and drawers on the odd chance they might find a leftover cut thread plug but otherwise it would at least a year...I said thanks, but I'll be needing that return UPS label.


"Flintlocks.......The Real Deal"
(Claims that 1:48" twists won't shoot PRBs accurately are old wives tales!!)

 

[Zonie]

Spiral thread inserts are handy for making repairs, and some places use them to have steel "working threads" in their aluminum parts. For what it's worth, it was against company policy to use these in the hardware for the Gas Turbine engines I designed.
That policy wasn't based on a weakness of the insert, but rather on the tendency for the inserts to "back out" when the fastener was removed.

As for their use in a pressure application like a spark plug hole, they work all right, but notice that in this application, the flat face of the spark plug seals the pressures by tightening against the cylinder head.
If the GM rework does not have a liner that completely covers up the helicoil and seals against the outside of the barrel, the high pressure gas will leak around the outside of the helicoil thread (in the barrel) and around the outside of the plug they screwed into it.
To say the least, this is a very poorly designed "fix".

If they truely wanted to fix this right, they would have had some oversize plugs made to fit into a properly tapped oversize hole. No helicoil required.

zonie

 

[roundball]

"...If the GM rework does not have a liner that completely covers up the helicoil and seals against the outside of the barrel, the high pressure gas will leak around the outside of the helicoil thread (in the barrel) and around the outside of the plug they screwed into it...to say the least, this is a very poorly designed "fix"..."

And GM's liners have nothing like that...they are literally a simple set screw with a hole drilled straight through them...and they don't have an natural 'stop'...you can screw them all the way down into the vent until they bottom out...no idea how they'd stay in place out against the pan...I never even try to use them, just throw them away and install a TC liner as part of setting up a new GM barrel to use.

This GM vent liner (set screw) was noticeably loose in the helicoil and you could just spin it in and out effortlessly by just rolling the allen wrench back and forth between thumb & forefinger...I am still in disbelief that GM would intentionally ship such a Rube Goldberg contraption.

I've seen other posts about dissatisfaction with the same helicoil approach GM has taken with their defective caplocks lately...they need to scrap that inventory of bad plugs and start fresh...they're already starting to get a bad rap for quality due to this, with the recall program for the past couple years. In light of that I'm doubly shocked that they've taken this helicoil bandaide approach.

Must have been a "bean counter" decision, not a product engineering / quality decision...a breechplug simply does not cost that much in the big picture of things, particularly when you consider they could also take a tax write off for the scrapped plugs.

And it wasn't like it was a dirt cheap clearance sale barrel or anything...the cost was $278 to have that .40cal Flint version made.

 

[ss1]

I sent my GM per back because of the helicoil.




there return rate has to be very high.

 

[CoyoteJoe]

Wow, $278 !! Considering one can buy a 36" GM barrel for $97.50 it seems they're getting near two hundred bucks for a breechplug, rib, sights and blueing. I wish I could get that rate. I've fitted GM barrels to several rifles and feel a bit guilty for asking $100 over the barrel cost.
I've never purchased one of the "drop-ins" because I can't see paying for sights I'd throw away and bluing I'd remove, but that was when the drop-ins were going for under $150. For $278 it ought to be gold platted at least. :grin:

 

[Mad Professor]

Hi Roundball,

If you remember I'm the one who had ignition problems with a 54 cal perc GM barrel. Turns out the helicoil insert on the nipple was screwed in too far blocking the channel to the breech. Rick Sanborn at GM said send it pack no problem (but I needed it for hunting ASAP). I snapped off the bottom two threads and no new problems....... so far.

GM claims this is the way they build all new perc. barrels. Has anyone brought one recently, if so do you have a insert too? Hope I was not given a BS story......

Anyway, back to your problem. On a perc barrel the nipple will hold the insert tight sort of analogus to one used for a spark plug repair on an engine. I've had no more new problems and have many more rounds through the barrel.

In your flinter I don't see what there is to hold it in place? A piss poor solution that never should have made it past quality control. Also, I'd be concerned (just like my perc barrel) that they may have "screwed up" screwing it in. That insert could direct all the flask up against the far wall of the breech if in too far resulting in ignition problems. I know that you've plenty of other rifles so your'e not hurting for something to shoot; send it back.

It's really too bad that GM can't fix something like this ASAP, I mean what good is a 1 year warrantee if you wait one year to get a new barrel fixed!!!

 

[roundball]

They're just trying to save money...rick Sanborn told me the other day that "as soon as they use up all existing plug inventory, they'll be re-implementing the cut thread process...that statement alone says he knows the helicoil is a bandaide and the cut thread process is superior, otherwise why change back to it :shake:
My first reaction is that I didn't want to trust it and that feeling is now locked in stone...he's sending me a UPS return label.

If it turns out I can't get a Flint .40cal for a year, two years, etc, so be it...it might even be that by then I no longer want one anyway...it was more of an interest to try another caliber than any actual need...he did say he was going to scrounge around and see if by chance there might be a good 15/16" plug in the back of a drawer somewhere, but he didn't sound optimistic.

Like you said, I have other MLs to shoot and won't miss having the .40 at all...got a couple thousand .395s on hand but worse case can always move those out if the Flint .40 never materializes.

It's time now to focus on hunting for the next several months anyway :thumbsup:

 

[Mad Professor]

It's sad that they couldn't just make some oversize liners to fit the oversize hole, that is proper liners with a rim to seat on the plug. A good machinist could produce all they need in an afternoon..........

From the sounds of things they will still have a "Micky Mouse" set up if they are just using drilled out set screws even with the new breech plugs :youcrazy: :shake: :bull: