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Unitizing

If Iwere going to go to the expense of unitizing a gas cylinder assy,
I would start with new USGI parts. Not a parts snob, I use after market parts, but if you're gonna spend money, build it on a solid foundation.
Just my two cents.

Honer
 

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GI gas cylinders are still available but I would also consider an LRB or SEI gas cylinder. They are both supposed to be of good quality. I haven't even really heard anything bad about SAI gas cylinders. Send it off to Ted or that guy 82nd has that does the discreet welding.

Tony.
 

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To permanently attach the front band to the gas cylinder by either drilling/tapping holes and screwing them together, or by welding them together. It can help accuracy in most cases. How much varies from case to case.
 

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I had Cepilot (that guy that 82nd ABN knows) weld one for me. His work is first rate, and is easy on the wallet. Not detracting from the others, but I wanted a welded one, and everybody else seems to do the "screw and glue" method. He also bent the front band ears up for me without asking, so that was a bonus.
 

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Discussion Starter · #7 ·
If Iwere going to go to the expense of unitizing a gas cylinder assy,
I would start with new USGI parts. Not a parts snob, I use after market parts, but if you're gonna spend money, build it on a solid foundation.
Just my two cents.

Honer
That's basically what I was thinking, but at the same time, how many people have ever had an issue with one of the major SAI parts? Especially a GC.

I know adding USGI parts (or the commercial equivalent - SEI, LRB, 7.62MM) will add value to the rifle, but I want a shooter not a mantle piece. And I don't EVER foresee myself getting rid of either of my M1As.
 

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Discussion Starter · #8 ·
I had Cepilot (that guy that 82nd ABN knows) weld one for me. His work is first rate, and is easy on the wallet. Not detracting from the others, but I wanted a welded one, and everybody else seems to do the "screw and glue" method. He also bent the front band ears up for me without asking, so that was a bonus.
Thanks for the head's up. I will PM both and get some more quotes. I was pretty set on the screw-n-glue method but if the price is right...
 

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As far as those particular parts go, unlike bolts, extractors, trigger parts, or magazines, I haven't observed that USGI v. Commercial Repop makes a hill of beans. I would still prefer a USGI or Sadlak piston and a USGI gas cyl lock + plug screw.

On unitization, welded is good, screwed & glued is good. Welded = quicker if the jig is set up. You keep the use of the spindle gas valve. Screwed & glued = easy to fix if a screw backs out. Need to anneal the band (hard steel) to drill and counterbore, but the annealed band is workable in fitting up snug to the barrel shoulder. Take your pick. 6 of one = a half doz of the other.
 

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Discussion Starter · #10 ·
As far as those particular parts go, unlike bolts, extractors, trigger parts, or magazines, I haven't observed that USGI v. Commercial Repop makes a hill of beans. I would still prefer a USGI or Sadlak piston and a USGI gas cyl lock + plug screw.
That's what I figured. Like I said, I don't really recall reading about SAI GC issues.

For the most part, I'm with you guys in that I would rather use USGI or the commercial equivalent (I'm still pretty set on 7.62MM parts despite the issues I have with them).

The fact of the matter though is why spend so much extra money on additional parts if it's truly unnecessary.

I wonder if Ted, et al. would have an opinion on which to use.
 

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That's what I figured. Like I said, I don't really recall reading about SAI GC issues.

For the most part, I'm with you guys in that I would rather use USGI or the commercial equivalent (I'm still pretty set on 7.62MM parts despite the issues I have with them).

The fact of the matter though is why spend so much extra money on additional parts if it's truly unnecessary.

I wonder if Ted, et al. would have an opinion on which to use.
Ted prefers screw-n-glue, Gus prefers welded. Both have their reasons and merits.
 

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Both types end up with similar results, so it probably doesn't make much difference which system of unitizing you use. My only problem with commercial gas cylinders is that some are not stainless steel. Some made by SEI are treated for a harder surface and I prefer not to unitize them with the screw and glue method. It eats my drill bits.
 

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Discussion Starter · #13 ·
Both types end up with similar results, so it probably doesn't make much difference which system of unitizing you use. My only problem with commercial gas cylinders is that some are not stainless steel. Some made by SEI are treated for a harder surface and I prefer not to unitize them with the screw and glue method. It eats my drill bits.
Are SAI GC's stainless steel?
 

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I cant really say Ive heard of any practicle considerations for using a USGI-HI quality($)
aftermkt GC/band ass over a SS SAI unit. Still given my druthers and $$ GI/SEI etc would be my preference if for no other reason personal satisfaction/assurance.
That said, while not unitized I shimmed a loose front band to a SAI GC with very good (trouble free/improved accuracy) results.

I cannot say for sure whether the SAI GC's are forged or cast SS while I believe, though dont take my word,GI's are forged.FWIW
 

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OK, I'm not a welder, so I'm going off what some welders have told me and some S.W.A.G. here.

I have noticed it is easier for a cast gas cylinder to warp in the welding process than a milled part and that is by using the same welding fixture to align the parts for welding. Usually, after welding, there is less adjustments that have to be made with G.I. parts than cast SAinc. gas cylinders to get them to go on the barrel properly.

On a couple SAinc. gas cylinders, I had to clear a good bit of metal so they would slide on properly. Now, "a good bit of metal" to me can be anywhere from .015" to .025", so we aren't talking about a huge amount of metal.

It is normal to have to clear a little metal in the area of the rear ring as the heat of the weld distorts the ring a bit AND the front band and rear or the rear ring of the gas cylinder may not be perfectly square and perpendicular to the barrel. However, I have found with cast cylinders and after welding, you may have to relieve some metal in the front ring to get the cylinder to go on the barrel properly. OK, this is a SWAG here, but I A$$UME this is due to the cast cylinders not being made "as square" to the corresponding surfaces of the barrel as a milled part. On one SAinc. cylinder, I REALLY had to take metal out of the front ring as well as the rear ring after welding, though the cylinder had gone on a barrel OK before welding. What I think happened with that cylinder was the holes in the ring were not properly aligned to each other and/or not properly aligned to the three keys or lugs that hold the cylinder in place on the barrel.

Some welders have told me welding the cast sylinders is more difficult to get the weld to stick properly.

Maybe we can get CEPilot or other welders to chime in on this one as I fully admit I'm groping a good deal on this question.
 

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Discussion Starter · #18 ·
Thanks for chiming in Gus. Have you been able to compare an SAI GC that was welded by you / another gunsmith versus an SAI NM GC (welded by SAI)? What I'm referring to is the metal that had to be removed.

Hopefully CEPilot can add to this like you mentioned. Any comments on the "screw-and-glue" method with SAI GC's? Maybe Ted can jump back in on that.
 

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MGySgt USMC (ret)
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Thanks for chiming in Gus. Have you been able to compare an SAI GC that was welded by you / another gunsmith versus an SAI NM GC (welded by SAI)? What I'm referring to is the metal that had to be removed.

Hopefully CEPilot can add to this like you mentioned. Any comments on the "screw-and-glue" method with SAI GC's? Maybe Ted can jump back in on that.
I'm not sure I have even seen an SAinc. welded GC.

Back in the early 1980's at Quantico, we tried the screw and glue method extensively. Then Mike Gingher came up with a way to weld them that the weld was hidden and was legal for NM Service Rifle then, I.E. it did not readily show on the outside. The screw and glue cylinders always shot loose within one shooting season and the welded cylinders never came loose. So we dropped the screw and glue and never went back.
 
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