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How important is the o ring in the tirant 45 piston

Posted: Wed Oct 16, 2013 3:24 pm
by jnitti1014
I have been trying to suppress my .45 for about a year now, between waiting for a barrel to having it fit etc etc. I now have a barrel that works with the slide but is too short for the piston, meaning when fully screwed in to shoulder it pushes the slide out of battery. Seems like my choices are to either find a thinner bushing, grind about 1/8-1/4 " off the piston bottom or both. I have the shorter 1911 piston and the pistol is an ATI 1911 GI. Thanks for any help in advance

Re: How important is the o ring in the tirant 45 piston

Posted: Wed Oct 16, 2013 3:50 pm
by Historian
jnitti1014 wrote:I have been trying to suppress my .45 for about a year now, between waiting for a barrel to having it fit etc etc. I now have a barrel that works with the slide but is too short for the piston, meaning when fully screwed in to shoulder it pushes the slide out of battery. Seems like my choices are to either find a thinner bushing, grind about 1/8-1/4 " off the piston bottom or both. I have the shorter 1911 piston and the pistol is an ATI 1911 GI. Thanks for any help in advance
Would a thin SS threaded (1/2" x 28 ID) ring, diameter larger than 1911 A1 barrel with a set screw
act as a 'shoulder' against which the can be tightened work?

Re: How important is the o ring in the tirant 45 piston

Posted: Wed Oct 16, 2013 7:26 pm
by jnitti1014
I don't think so, the problem is the barrel is to short for the threads to bottom out/screw all the way in on the piston on the piston thread

Re: How important is the o ring in the tirant 45 piston

Posted: Wed Oct 16, 2013 11:11 pm
by jnitti1014
I guess what I'm asking is, can I chop 1/4 " off the bottom of the piston so it threads or screws all the way in without throwing the gun out of battery, effectively shaving off the o ring, and not blow my can up?

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 12:05 am
by rjacobs
Give this thread a few days and I would bet somebody from AAC will be by.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 6:01 am
by HK45
I think AAC has a fix for that problem.

Read the description for the Tirant piston.
https://www.silencershop.com/shop/aac-ti-rant-45-piston

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 9:22 am
by rjacobs
HK45 wrote:I think AAC has a fix for that problem.

Read the description for the Tirant piston.
https://www.silencershop.com/shop/aac-ti-rant-45-piston
If you are talking about the section that says "for 1911's we have a short piston", he already has the short piston and needs it to be shorter.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 11:07 am
by RJT
Have a short adapter made that screws to the bbl short of the slide, then screw the piston to it. Just make sure it is bore centric.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 11:42 am
by rimshaker
Sounds like the main problem is wrong threaded barrel length. Fix that and all other problems go away.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 11:47 am
by Pman5KMO
jnitti1014 wrote:I have been trying to suppress my .45 for about a year now, between waiting for a barrel to having it fit etc etc. I now have a barrel that works with the slide but is too short for the piston, meaning when fully screwed in to shoulder it pushes the slide out of battery. Seems like my choices are to either find a thinner bushing, grind about 1/8-1/4 " off the piston bottom or both. I have the shorter 1911 piston and the pistol is an ATI 1911 GI. Thanks for any help in advance
sounds like you got a barrel designed for a compensator (think muzzle brake-ish) and not a suppressor. The shoulder behind the threads should have some clearance between it and the bushing/slide, usually 1/8"-1/4"

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 11:55 am
by Pman5KMO
rjacobs wrote:
HK45 wrote:I think AAC has a fix for that problem.

Read the description for the Tirant piston.
https://www.silencershop.com/shop/aac-ti-rant-45-piston
If you are talking about the section that says "for 1911's we have a short piston", he already has the short piston and needs it to be shorter.
He needs a new barrel.... otherwise any 'ring' or other device would likely void any warranty claims, and be a weak point prone to failure. Sounds like the barrel is made for a flush fitting screw on comp, OR just plain screwed up.... I would contact the barrel MFG. Most .45 can pistons on 1911 pistols and many other .45 will shoulder on the muzzle of the barrel. It could also be that the piston itself is out of spec (it happens regardless of MFG).

OP needs to measure length of threads, and length behind threads. Compare those to the AAC thread spec drawings... you will need a good accurate caliper to do this. If barrel is in spec, then it is the piston. If piston is out of spec, then contact MFG.

For a 1911 with the GI style recoil assy you want the flush fit.... if you have a guide rod you need the other piston.

For 1911 you want .578x28 flush.... it should be marked as such.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 11:56 am
by Pman5KMO
rimshaker wrote:Sounds like the main problem is wrong threaded barrel length. Fix that and all other problems go away.
with 1911 pistols they make flush threaded barrels designed for comps.... probably got one like that. They lack the rear 1/8-1/4" of clearance behind the threading shoulder.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 12:33 pm
by jnitti1014
Pman5KMO wrote:
rimshaker wrote:Sounds like the main problem is wrong threaded barrel length. Fix that and all other problems go away.
with 1911 pistols they make flush threaded barrels designed for comps.... probably got one like that. They lack the rear 1/8-1/4" of clearance behind the threading shoulder.

Yep that's the problem, however I really don't want to dump the money into a new barrel and fitting it. Can anyone tell me what exactly that oring actually does? And yes I have the short piston.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 3:25 pm
by Pman5KMO
jnitti1014 wrote:
Pman5KMO wrote:
rimshaker wrote:Sounds like the main problem is wrong threaded barrel length. Fix that and all other problems go away.
with 1911 pistols they make flush threaded barrels designed for comps.... probably got one like that. They lack the rear 1/8-1/4" of clearance behind the threading shoulder.

Yep that's the problem, however I really don't want to dump the money into a new barrel and fitting it. Can anyone tell me what exactly that oring actually does? And yes I have the short piston.
O-ring on barrels is to reduce/prevent loosening and is typically found on LH threads for some reason. The O-ring on the rear endcap of a pistol can (where the piston goes) helps to seal the unit, and act as a bushing of sorts. Some have them on the portion where the end cap goes into the tube as well.

The comp style barrels are useless with a suppressor, and will only cause problems, there is no feasible method to adapt it for suppressor use. The only real option would include having someone make an extension, however .45 1911 barrels are generally too thin to do this reliably enough to ensure concentric threads.

Now it is odd to have a barrel in the proper threading but with the 'comp' length, as most comps are .575x40 thread pitch. MidwayUSA does have a cheap swenson threaded barrel, that seems to work ok for some, but definitely not as near high quality as a storm lake or one of many other MFG, but you get what you pay for.... I say that having one of those swenson threaded barrels.... it's ROUGH to say the least, and requires a lot of work to get it to even feed anything but hardball, and to function reliably, but the threads were in spec. and it works fine for my .45 pistol cans. May not be the most accurate, but it goes bang every time I pull the trigger (after all the work I put into it) and was easy to fit (the hood needed .005 taken off, and bottom lugs narrowed and opened up for link for full clearance, as well as attaching link and pin... I bought a link and pin set to ensure proper sizing) just all the other work, the polishing, having concentricity verified, and all that. Sure I plan on upgrading it to a storm lake or other much higher quality barrel, but if careful and everything is verified, then properly fitted it will work, just don't expect top notch performance from the barrel.

Re: How important is the o ring in the tirant 45 piston

Posted: Thu Oct 17, 2013 4:36 pm
by jnitti1014
Ok failing that, can anyone recommend a gunsmith who can fit a barrel to a slide and what's the average cost? If I can keep it under $150 I'll send it to the smith, if not I'm going to buy an extra piston and shave 1/4 " off it.

Bender, any opinions?

Re: How important is the o ring in the tirant 45 piston

Posted: Fri Oct 18, 2013 5:29 pm
by MJF1911
Why don't you call a few gunsmiths and see what they charge? My Storm Lake cost $40 to have fitted.

Re: How important is the o ring in the tirant 45 piston

Posted: Fri Oct 18, 2013 6:55 pm
by jnitti1014
Can you tell me which smith that was? I'll call him.

Re: How important is the o ring in the tirant 45 piston

Posted: Sat Oct 19, 2013 1:08 am
by MJF1911
Do you not have a local gunsmith? Shipping both ways is going to be expensive.

Re: How important is the o ring in the tirant 45 piston

Posted: Sat Oct 19, 2013 8:33 am
by jnitti1014
I really do not.

Re: How important is the o ring in the tirant 45 piston

Posted: Sat Oct 19, 2013 4:17 pm
by jnitti1014
Ok I revisited this again and it looks like it only needs to be shortened by about 1 1/2 turns of the piston. Looks like I can still keep the o ring. Any suggestions on which is better, grinding it down or having a machinist shave it off?

Re: How important is the o ring in the tirant 45 piston

Posted: Sat Oct 19, 2013 6:02 pm
by Bendersquint
jnitti1014 wrote:Ok I revisited this again and it looks like it only needs to be shortened by about 1 1/2 turns of the piston. Looks like I can still keep the o ring. Any suggestions on which is better, grinding it down or having a machinist shave it off?
Machinist turning it is better than grinding.

Unless its a CNC grinder then I would personally grind it.