1911 Series 70 / 80?


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devildave31
October 21, 2010, 10:19 PM
Can someone please explain what the functional differences between a standard 1911A1 and a series 70 and a series 80 are? If I undertand correctly, series 80 pistols have the firing pin block safety but what constitutes a series 70?

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DonRon
October 21, 2010, 10:44 PM
No firing pin block drop safety. Springfield gets away with it by only having a 9mm firing pin made out of titanium and a very heavy firing pin spring. It made California happy, if that is possible.

devildave31
October 21, 2010, 10:46 PM
And how does that differ from an A1?

DonRon
October 21, 2010, 10:53 PM
The original 1911A1 had a steel .45 caliber larger diameter firing pin and a weaker spring. If they were dropped and hit smack on the muzzle there was enough weight in the steel larger pin to create enough inertia to hit a primer and ignite it. One of our guys dropped his Colt 1911A1 and it hit the floor and fired and when we found it it was still cocked and locked with the empty brass still in the chamber. It must have went up about 40 feet in the air when it went off.

devildave31
October 21, 2010, 11:08 PM
So then when I see a part listed on Midway USA for example and it says "will fit series 70", unless it is a firing pin or firing pin spring, then it is a moot point?

That brings up another question. I was looking at Caspian Slides and frames and noticed that all the slides come drilled for a .38 Super firing pin. If I was wanting to build a .45, would I need to have the hole enlarged? Can you use a .38 firing pin with a .45 frame?

rklessdriver
October 21, 2010, 11:16 PM
70 Series COLT Government Model pistols have a collet barrel bushing and accurizer barrel. The guns all have MKIV Series 70 on the barrel and the slide. There are 2 versions the early LRM (Large Roll Mark) silde and later SRM (Small Roll Mark) slide. Those 3 things make a Series 70 a Series 70. It does NOT have a firing pin block and utilizes the same fire control system as the orginal M1911 and M1911A1 Military pistol. They were all 5" pistols.... There were NO Series 70 Commanders or Officers ACP's ever built... Even thou people often (in error) call pre 80 Series Commanders as such.

80 Series Government Model pistols have a firing pin block system so that the pistol will not fire if it is dropped. Some 80 Series had the collet busing and accurizer barrel up till about 1983 when COLT finally ran out of them. After that time all 80 Series had a standard barrel bushing and barrel used. At some point COLT narrowed the barrel hood width to the National Match specifications. In 1992 COLT came out with an economy version often refered to as the ORM (Old Roll Mark) which had "M1991A1" blazen across the slide... Some years later they went to the much nicer looking NRM (New Roll Mark) which they use to this day. There are Series 80 Commanders and Officers ACP's and they are marked with the roll marks I listed above.

They are both commercial pistols only manufactured by COLT. The Series 70 and some Series 80 pistols resemble the M1911A1 in appearance and external features. Some have a mix of M1911 and M1911A1 features such as straight/arched mainspring housings and long/short triggers.

The 1911A1 is a military pistol. It has a standard barrel bushing and barrel. Not all A1's were manufactured by COLT.... Remington Rand, Ithaca, Union Swith and Signal, and Singer made 1911A1's for the US Government as well as COLT. The A1 was an improvement on the M1911. The changes were milled finger reliefs around the trigger guard, shorter trigger, arched mainspring housing, and a longer grip safety tang. Finsihes varied from Blued to Dulite to Parkerized depending on manufacturer and year of manufacture. Later mfgr M1911A1's have superior heat treating on the slides.
Will

DonRon
October 21, 2010, 11:31 PM
So then when I see a part listed on Midway USA for example and it says "will fit series 70", unless it is a firing pin or firing pin spring, then it is a moot point?

That brings up another question. I was looking at Caspian Slides and frames and noticed that all the slides come drilled for a .38 Super firing pin. If I was wanting to build a .45, would I need to have the hole enlarged? Can you use a .38 firing pin with a .45 frame?
That 9 mm titanium firing pin was only in some Springfields I worked on. I don't know about the other markers. I refuse to do anymore 1911 work. Too much of a hassle for the exact reason you mention. The 1911 is totally bastardized today.

gbw
October 22, 2010, 12:27 AM
You may use normal 1911 S80 version parts (firing pin and spring and stop and grip safety) on most any 1911 pistol. On a Caspian slide you'll need the smaller firing pin. S80 or standard doesn't matter. So far as I know all S70 parts are interchangeable with a standard 1911A1 except, as noted, the bushing. Nobody likes the S70 bushing.

The 1911 S80 parts mentioned above are modified with relief cuts that won't interfere, they work fine in standard guns.

To actually use the S80 FP safety, you must have the S80 versions of the parts above, plus a frame and slide machined to accept the extra parts for the S80 FP safety system, and some other parts - levers and spring and plunger IIRC.

The smaller firing pin works fine, I've a couple of all Caspian .45s. No problems.

9mmepiphany
October 22, 2010, 01:12 AM
Can someone please explain what the functional differences between a standard 1911A1 and a series 70 and a series 80 are? If I undertand correctly, series 80 pistols have the firing pin block safety but what constitutes a series 70?
No firing pin block drop safety. Springfield gets away with it by only having a 9mm firing pin made out of titanium and a very heavy firing pin spring. It made California happy, if that is possible.

While people will use the terms 70 series and 80 series applied to 1911 clones manufactured by other makers, the terms only apply to the Colt line of pistols.

Taking the 1911A1 as the base pistol:

The 70 series added the collet (multi fingered) barrel bushing and the Accurizer (flared muzzle) barrel for tighter lockup and smother function due to the tapered barrel behind the flared portion.

The 80 series did away with the 70 series bushing and barrel (good idea, not so good in execution) and added the Firing Pin Block

Springfield has never produced a 70 or 80 series equivalent model

devildave31
October 22, 2010, 01:13 AM
If I recall correctly, don't the Caspian slides also have a slightly higher (or was it lower?) hole for the firing pin? If so, does that create any considerations when doing a build?

gbw
October 22, 2010, 09:54 AM
So far as I could tell no difference in the Caspian FP hole except it's smaller. The Caspian guns I did (stainless) have .050" +/- vertical lug engagement and the FP is well centered.

Only problem I've had with Caspian is the frames, which allow Kart NM barrels to overhand the feed ramp, or nearly so. This can be adjusted but it's never seemed quite right to me. I've not seen anybody else make this complaint so likely it's something i'm not seeing correctly.

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