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View Full Version : SP-1 help! Won't load on its own.


Spyder
12-15-2008, 2:02 PM
I've been having trouble with my SP-1 upper. It's an original Colt, large pin. I have it on a small pin Doublestar lower with the little adapter pin. I'm assuming that is where my problem is, but can't seem to tune it right.

Hand cranking it, it loads and chambers and ejects just fine. When I fire it, it ejects the spent cartridge fine but it won't load the new one from the magazine. The bolt closes home and when I pull the trigger it goes *click* on an empty chamber. But if I pull the charging handle back, it loads the next round just fine. Makes it kind of a bolt-action rifle and is rather irritating.

It does it with all the magazines I've tried and does it about 8 of ten times, if not more. I'm assuming that I have to rotate the little offset pin adapter to the proper spot, but I've tried that over and over and have not found the right spot. At first it would fail to chamber as the brass would catch on the feed ramps. I got it, by turning the pin adapter and changing the spacing on the upper to lower fit, to stop doing that, but it still doesn't want to strip the top round from the magazine and load it on its own.

It's weird to me that it won't do it on its own but has no trouble at all when I cycle it by hand. :confused:

For more experienced minds than mine, thanks ahead of time!

Lateralus
12-15-2008, 2:35 PM
I have ZERO experience with all the mentioned hardware and have never dealt with a large pin lower, but Ive thought about why and the only answer I can come up with is that when the gas cycles is the carrier does not return enough. If the hammer hits the firing pin and the bullet is fired, the lower has done its job. Maybe the carrier starts returning while it is still over the mag. Maybe the gas system is janked, or the buffer/spring has issues. This is all just wild speculation at this point though.

By the way, where are you located? Im sure a calgunner is your area might be able to help.

Blacktail 8541
12-15-2008, 2:41 PM
The adapter bushing has nothing to do with your problem. Your weapon is doing what is known as short stokeing. Your problem is somwhere in your gas system. Or you are useing under powered ammo.

Check your gas key on your bolt first, then see if there are any restriction in the gas tube and front site base. One way to do this is by attaching a rubber tube to the gas tube and blowing to see if air passes freely thru the system or useing some type of smoke to visually check.

ETA: the addapter bushing should be orientated so that the upper and lower gap is at its smallest.

redcliff
12-15-2008, 2:46 PM
Lube your bolt carrier...WELL.

Spyder
12-15-2008, 5:45 PM
Thankee sai to all. I will do the above mentioned tonight and try it at the range manana. I have been running it pretty dry so after I check the gas key and tube, I'll lube it up and put 'er back together. I hope its that easy!

I am just North of Yuba City, so I'll be out at the Oroville range at some point tomorrow to test it out. I was there for 45 minutes or so today 'cause I got the itch to get out of the house and was reminded of this irritating issue. I'll report back and letcha'll know what the problem was!

Blacktail 8541
12-15-2008, 6:30 PM
PM me when you are going to be there. Might be abe to meet you and help trouble shoot. I live in Oroville.

technique
12-15-2008, 7:47 PM
Do you have a standard triangular FS? Is it a Bull barrel?

Spyder
12-15-2008, 8:48 PM
Bird cage, not a bull barrel.

Spyder
12-15-2008, 9:15 PM
Well, after checking the gas tube and getting good airflow, I pulled it apart, checked the rings, they're fine. Coated the BCG in Tetra Lube grease, massaged it in for a minute, wiped it down nice and clean, put it back together and put a couple of good sized drops of CLP in strategic places. Immediately FEELS better to pull it back and let it close. It used to, sometimes, hang up just before being completely closed if I didn't let the charging handle go when it was all the way back. Now I can let it in almost all the way and it still closes properly.

I've got a good feeling about test firing it in the morning. Wish me luck and thanks to all! :)

superhondaz50
12-15-2008, 10:50 PM
Sounds like gas rings. Your upper is 25ish to 40ish years old so they may be kinda worn, its a very common problem I see very often. Since your using a conversion bushing, check the gap between the upper and lower. I have seen some bushings rotate while the gun is together leaving a 1/8" gap between the two, which caused the bolt to pass right over the cartridge when the gun cycled. But more than likely its your rings.

Spyder
12-16-2008, 3:17 PM
Nah, its damned near brand new. If the guy I bought it from hadn't told me he fired any through it, I wouldn't have known.

Didn't make it to the range today...too busy fixing the truck for a 4x4 snow run this weekend! Maybe tomorrow morning...