Colt Delta 10MM Recoil Reduction

[73Driver]

I am looking at adding a 10MM Delta to the stable and understand that there is a history of frame cracks in this model. I was wondering if the small radius Firing Pin Stop modification might help with this. I have modified and installed the small radius Firing Pin Stop modification (exactly per 1911Tuner's instructions) in all my 1911s and have become proficient enough that I have modified several friends 1911s as well. Also, would a shock buffer help reduce this frame damage? Any thoughts?

[RickB]

History of frame cracks is right; pre-production guns were cracking, back in the mid-eighties, so Colt modified the design to fix it. The story is still hanging around, 20+ years later. I think you could probably wear the gun out pretty quickly, if you shot enough full-power rounds through it (200@1200, 180@1300, etc.), but there's little need for that. I have the small radius stop on all of my 1911s, but think it does the most good on the Delta Elite. I'm using a Cominolli frame-saver guide rod (belt AND suspenders), 25# main, and 20# recoil. The gun runs great, and the buffer pads lasted over 1000 rounds, which suggests there's not a lot of shock to buff. Case ejection is still very energetic, which makes tracking them down a hassle, but that's no big deal.

[1911Tuner]

The answer to Driver's question is a qualified yes. It was actually Ned Christiansen who first experimented with the small-radius stop with a 25-pound mainspring and an 18-pound recoil spring to tame the Big 10's recoil.

The real problem with the full-power 10 in a 1911 is the slide. The most highly stressed point is in the ejection port, and the usual spot for it to crack is in the corner adjacent to the breechface and the top, left edge of the port. This comes from the
case slamming into the breechface under recoil. There's a corner there that contains stress risers...and the cracks are most likely to start at stresspoints in the steel.

The second most likely place is adjacent to the first lug wall in the lower right side of the port...and the entire port area becomes stretched much the same as the topstrap on a revolver does after hard use with hot ammo. The small-radius stop system can't do anything about that, I'm afraid.

[RickB]

Tuner - Will fitting a barrel with equal longitudinal engagement of all lugs help the situation? It seems like a lot of production guns must be riding on one lug, and that would contribute to the problems that you cited.

[1911Tuner]

Will fitting a barrel with equal longitudinal engagement of all lugs help the situation?

Not much as far as the stretching of the area between the first lug wall and the breechface, and the one spot most likely to crack. Probably some in the second most likely place...but the port area is thin, and there's that stress riser-filled corner.

The 1911 will withstand the pressure. No doubt about it. The .38 Super proved that. The 1911 will also fare well with a heavy bullet.
Put them both together and you're overstressing the slide in the thinnest, most failure-prone areas.

It would be wise to heed the warning that was given decades ago on the K-frame Model 19 Smith & Wesson revolver. ".38s for practice. .357s for business." The reasoning is the same. The K-frames' topstraps were too thin to stand up to a lot of full-power .357 ammo. Download the Big 10 for range practice and reserve the hot stuff for more serious occasions.

[grendelboy]

Not an expert by any means but I have owned a few 10mm 1911s in my day. My Delta had the later model frame with the cutout made. I think the accounts of cracking frames etc are a bit exaggerated to be honest. The gun ran the hottest loads with no signs of frame fatigue or battering.

I run my current RZ-10 with an 18.5 recoil spring, no shok buffs. The RZ also comes from Dan Wesson with a very small profile on the FPS. I bought an EGW model in the hopes of swapping it out for this same purpose. I was pleasantly surprised to find it was not necessary so I put the EGW in my Kimber .45

[1911Tuner]

I think the accounts of cracking frames etc are a bit exaggerated to be honest.

Frame cracking/battering wasn't the problem. It was with the slides. Colt discontinued the Delta Elite after a relatively short run for a few reasons...but lack of sales wasn't one of'em. There was a rumor goin' 'round that Colt had plans to beef up the slides in the Deltas just before they dropped it from their lineup.

[RickB]

I read somewhere that the Delta slide it somewhat heavier than a .45 slide, but I can't see where there would be any extra material. I read, again, "somewhere", that the post-'91 enhanced slides don't really have a rib added at the top, which would add some material/weight, but instead have everything that doesn't look like a rib machined off, so no help there.

[1911Tuner]

I read somewhere that the Delta slide it somewhat heavier than a .45 slide, but I can't see where there would be any extra material.

There was supposed to be a beefing up...but whether or not it ever materialized is unknown. Somebody who has studied up on the Deltas may be able to provide more accurate information.

If the slides were beefed...the most advantageous place would have been at the weakest place...the area between the breechblock and the first lug wall. Simply adding weight wouldn't do anything much beyond slowing it down a little...and would actually make it more prone to crack at the weak area if it was added forward of the port area.

Machining the breechface with a little heavier radius in the corner would go a long way toward forestalling the failure. The sharper the corner, the heavier the concentration of stress risers. But, they didn't ask me about it. :D

[erwittry]

Would it be safe to assume the same type of cracking, stress issues with other more exotic calibers like 460 roland or 400 cor-bon? Would using a "GI" style slide with a non-lowered ejection port help relieve this?

[1911Tuner]

Would it be safe to assume the same type of cracking, stress issues with other more exotic calibers like 460 roland or 400 cor-bon?

Yessir. Absolutely. Granted, a new gun or one without much use wouldn't break in a couple hundred rounds...though the lugs may suffer unless carefully fitted for equal bearing in horizontal lockup...but stress is stress. The higher the stresses, the shorter the life of the gun.

Would using a "GI" style slide with a non-lowered ejection port help relieve this?

Not much. It would take a little longer for the port area to stretch and open up the headspace...but as above...added stress shortens the useful life of any gun. It wouldn't help at all with the crack-prone area adjacent to the breechface.

Recently, there was a story on one of the gun boards...might have been this one. I can't remember offhand. The guy had either a Baer or a Brown pistol that was having some minor issues...so he sent it back. Pretty sure it was an Ed Brown...so I'll just say it was.

He spoke to Ed on the phone about his gun, and he was asked what kind of ammo he was using. He replied that it was handloaded 200-grain lead SWC at about 950 fps.
Brown's response was one of alarm, and he said: "Whoa, man! You're gonna break my gun!"

A lead bullet is easier on the gun in a lot of ways...and the stress that's being described is one of those ways. If Ed Brown was concerned about 200 grains at 900 fps in a well-fitted gun...what will the Big 10's 200 grains at 1250 do to a factory assembled pistol? What will the Rowland and Super...with the "Drop-in" approach do?
The working pressures of those rounds exceed the .45 ACP's proof-levels...which are 25% over industry standard.

Questions like this beg to be asked...and the obvious answers should be carefully considered. The 1911 is a good, strong design...but it's got certain limits. Push too far past those limits and you're asking for an expensive repair.

[Sniper350]

If you want to shoot the 10mm without concern .......... use the proper tool for the job :) I carry the S&W 1006 ...built like a tank ......... and you can work a nice DA trigger pull on this gun. Sure it's heavy ! but I carry one daily CCW ...this way I don't have to make any trips to the gym.

I heard it from a reliable source that Colt dropped the Delta 10mm due to the shear number of warranty claims. A lot of problems came from owners "handloading" the 10mm to super hot spec.s I noticed many of the ammo makers downloading this cartridge over the years .......... from the hot round it once was back in 1986 - not sure what they wanted to accomplish.

LIke others have said, the 1911 design has limitations ......... handling the 10mm chamber pressures pushing a 200 gr bullet is not what JB had in mind. :D

JF.

[1911Tuner]

I heard it from a reliable source that Colt dropped the Delta 10mm due to the shear number of warranty claims.

Yeppers. Care to venture a guess as to what kept breakin'?

. handling the 10mm chamber pressures pushing a 200 gr bullet is not what JB had in mind.

Pressure isn't the only factor. The gun is more than strong enough to handle the pressure. It's the recoil impetus at the breechface that was bustin'em.

[paul45]

Frame cracking/battering wasn't the problem. It was with the slides. Colt discontinued the Delta Elite after a relatively short run for a few reasons...but lack of sales wasn't one of'em. There was a rumor goin' 'round that Colt had plans to beef up the slides in the Deltas just before they dropped it from their lineup.Produced from 1987 to 1996 is a relatively short run?

I heard it from a reliable source that Colt dropped the Delta 10mm due to the shear number of warranty claims.Care to name that reliable source......I need alittle proof to believe that story. :D

[erwittry]

Not that I'm in disbelief, but I am surprised that a Colt and others wouldn't do a "torture test" and find the stess problems...

I guess if you hand-load, you could practice with rounds toned down to the 40SW level. I'm assuming that 40sw wouldn't push the limits as much....

[1911Tuner]

I need alittle proof to believe that story.

Well...I didn't document all the busted slides...but along about the time that the Delta hit the streets, I was workin' the job in a local gunshop, in addition to my night job at RJR Tobacco. A small shop that sold a huge number of guns in the area. Their volume outstripped any two shops in the state.

Within a short time, a good many of the Deltas that they sold were comin' back with cracked slides and cracked/deformed/sheared upper barrel lugs. Nothin' that I could do about the slides, and they were under warranty...so they went back to Colt. Some of'em came back a second time. Colt again replaced the busted parts...usually slides...but this time, they came with a nice form letter that stated simply: "No more."

About half the ones that came back belonged to guys who didn't handload...and we had to figure that overpressured or junk reloads weren't the prime cause. So...We asked. Seems that the guys who bought'em and put'em up weren't bustin' their guns. The ones who were wringin'em out on a regular basis...were.

Colt didn't drop the Delta for lack of sales. They could barely meet demand...and many buyers placed an order for a Delta and waited for up to 3 months for delivery. A company doesn't drop a successful product unless there's a problem with it...and it reaches a point of diminishing returns due to all the warranty issues.

The Big 10's were violent. Pressures are quite a bit above proof levels for the SAAMI standard .45 ACP cartridge, which...with the standard 200-grain bullet...put the recoil impetus about on a par with the .41 Magnum.

The 1911 wasn't designed to handle those kinds of stresses. It's over-engineered for the .45 round...but even Smith & Wesson will admit that the .41 and .44 Magnums are a bit much for the N-frames...and full-powered ammunition should be used moderately.

The problem is that in both the Colt Delta Elite and the big-bore magnum revolvers...many shooters without a full understanding of exactly what sort of stress the "Romp and Stomp" ammunition places on their guns...want all the ruckus that the caliber will afford. The result is cracked slides and stretched topstraps.

Smith & Wesson went through a similar period with the .357 Magnum K-Frame revolvers...and recommended .38 Special ammunition for the bulk of shooting done. The issues with the K-Frames were a deciding factor in the development of the L-Frame revolvers.

[1911Tuner]

Not that I'm in disbelief, but I am surprised that a Colt and others wouldn't do a "torture test" and find the stess problems...

They already knew what it was. No need to do a torture test.

Anywhere you have a corner, you have an area of concentrated stress...known as a
"Stress Riser." If you impose heavy loads onto an area of concentrated stress...a crack will eventually start. How long that takes depends on how concentrated the stresses are and how much load you apply. Naturally, the higher the load, the sooner the riser produces a crack. The sharper the corner, the more the stress is concentrated.

One of the critical areas in a 1911 slide is the corner at the side of the slide at the
junction of the breechface guide blocks. Just behind the guide blocks is the breechface itself. When the cartridge fires, all the rearward force generated by the firing is absorbed by the breechface as the case rim slams into it...which places a sudden, violent tensile stress on the corner...right where the stress risers are concentrated. The harder the "punch" the more the area is stressed, and the sooner it lets go.

A nice fillet in that corner would forestall the tendency to crack...but it wouldn't stop the port area between the first lug wall and the breechface from stretching the same way that a revolver topstrap stretches, which causes headspace to increase...which allows the cartridge case to "back up" and lose case head support. If enough case head support is lost, the case blows out at the bottom...and when you're working with nearly double the pressures that the gun was designed around...even though 10mm brass is probably thicker and tougher than .45 ACP...it doesn't require as much loss of head support to rupture the case.

[thejeepster]

A proud owner and sometimes shooter of a "later" Delta, I've not had any problems with it. Tuner, I really enjoy your posts, and was wondering what I can do to mitigate any issues. I only shoot around 200-300 rounds a year. All factory (shot up all my handloads.. grin), and I've noticed that the factory rounds you can find now are "downloaded" from the original 10mm. (aka Norma, etc). So with a gun you enjoy, what can I do to minimize (other than not shooting) any damage. I'm using 22 lb wolff recoil springs.. would the "reduced radius" FP stop help? or is it just a matter of too much cartridge for the platform?

[paul45]

Well...I didn't document all the busted slides...but along about the time that the Delta hit the streets, I was workin' the job in a local gunshop, in addition to my night job at RJR Tobacco. A small shop that sold a huge number of guns in the area. Their volume outstripped any two shops in the state.

Within a short time, a good many of the Deltas that they sold were comin' back with cracked slides and cracked/deformed/sheared upper barrel lugs. Nothin' that I could do about the slides, and they were under warranty...so they went back to Colt. Some of'em came back a second time. Colt again replaced the busted parts...usually slides...but this time, they came with a nice form letter that stated simply: "No more."

About half the ones that came back belonged to guys who didn't handload...and we had to figure that overpressured or junk reloads weren't the prime cause. So...We asked. Seems that the guys who bought'em and put'em up weren't bustin' their guns. The ones who were wringin'em out on a regular basis...were.

Colt didn't drop the Delta for lack of sales. They could barely meet demand...and many buyers placed an order for a Delta and waited for up to 3 months for delivery. A company doesn't drop a successful product unless there's a problem with it...and it reaches a point of diminishing returns due to all the warranty issues.

The Big 10's were violent. Pressures are quite a bit above proof levels for the SAAMI standard .45 ACP cartridge, which...with the standard 200-grain bullet...put the recoil impetus about on a par with the .41 Magnum.

The 1911 wasn't designed to handle those kinds of stresses. It's over-engineered for the .45 round...but even Smith & Wesson will admit that the .41 and .44 Magnums are a bit much for the N-frames...and full-powered ammunition should be used moderately.

The problem is that in both the Colt Delta Elite and the big-bore magnum revolvers...many shooters without a full understanding of exactly what sort of stress the "Romp and Stomp" ammunition places on their guns...want all the ruckus that the caliber will afford. The result is cracked slides and stretched topstraps.

Smith & Wesson went through a similar period with the .357 Magnum K-Frame revolvers...and recommended .38 Special ammunition for the bulk of shooting done. The issues with the K-Frames were a deciding factor in the development of the L-Frame revolvers.Pretty interesting! And I certainly remember S&W going thru the K frame issues. I had a new model 66 back then and remember being a little put out when I heard "too many .357s will shoot it loose". I thought then why make it a .357?? Still a wonderful piece. I also bought a Smith 1066 new in '90 that was a tack driver, I choose that over a blue Delta at the time.....wound up getting a Delta some years later that was a great shooter as well. Thanks for the interesting answer......

[1911Tuner]

Pretty interesting!

Here's more...

Earlier this fall, a friend of mine called me and asked me to rebarrel and rebuild an early Series 80 Colt GM...por favor. He told me that he'd gotten a real deal on it from a guy who admitted to shooting it hard with factory +P and the equivalent handloads. Some 25,000 rounds, by close estimation. Note that +P .45 ACP doesn't come even close to
10mm levels...pressure or recoil impetus.

25,000 rounds...

Whenever I go to fit a barrel hood, I normally wind up having to take about .010 inch or so off the hood length to get the barrel into the slide. I had to take .002 inch off this one. I've never encountered a Colt that had been machined that far out of spec between the breechface and the first lug wall. Ever. The slide had stretched that much, and I didn't even have to finish ream the chamber to set the headspace after I got the barrel fitted. Just a light spin or two without deepening the chamber to clean up the leade forward of the shoulder was all I had to do.

Here's the kicker...

Even though the barrel had little clean rifling left, it still shot pretty well. Dennis reported that he'd noticed a slight bulge in the fired brass just ahead of the case head. The stretch had taken the headspace so far out that it had started to lose support. Out of curiosity, I checked the headspace with the old barrel. I used a NO-GO gauge and an .020 feeler gauge before I hit bottom. With a mid-spec case length of .890 inch...he had .052 inch of headspace.

[TonyW]

How to really reduce the recoil on a Delta 10!
OK- no bashing allowed - -this was done on a very early model after the first reports of recoil damage in order to attempt to salvage the gun -sort of an experiment by a gunsmith. It does make the gun a pleasure to shoot - on the other hand I'm sure it doesn't pack the wallop of a 10mm anymore. Sure breathes fire at night :D :D Not too good an idea to hold the gun close to your body either. :scared:

The 'smith said it was the toughest steel he had ever encountered - ruined several bits doing the cutting.

http://i89.photobucket.com/albums/k225/TonyW_01/Delta10.jpg

[1911Tuner]

How to really reduce the recoil on a Delta 10!

Works nicely to reduce muzzle flip and perceived recoil...but won't do a thing for the stressed area in the slide...because pistols generate about 90% or more of the total recoil impetus within the first half-inch of bullet movement...well before the ports ever come into play.