9mm Major - Cracked Slide

[BillChunn]

At this weekend's local match, the gun became noticeably harder to manually cycle at the "Make ready" command. It made it through the first two stages and then on the third (of four) it turned into a single shot. The slide would remain rearward and not return to battery. Had to grab the slide racker and force it forward for every shot.

The gun is about 10 years old. I had it built as a backup gun when my original broke at a match in upstate New York. The pair were in 38 Super and ran quite well for a number of years. I got out of the game and sold both guns then returned and bought this one back from the guy I sold it to.

Matt Cheely converted it to 9mm Major and am running 124 grain Montana Gold at a ~170 power factor.

The crack goes from the radius of the ejection port down to the bottom of the slide. It was not noticed immediately as it was behind the scope mount. There is another small crack that has started at the top of the breachface so basically this Infinity slide is toast. The gun is running a standard configuration recoil spring, reverse plug and guiderod. Pictures are in post #4 below.

My question is how to prevent this on the replacement slide?

Any and all suggestions will be appreciated.

Thanks,

BC

Edited March 19, 2013 by BillChunn

[Hammar]

Just out of curiosity, what powder are you using?

[latech15]

How many rounds through it?

As long as you have the gun sprung properly and are running good loads, (not too hot) then I am at a loss as to what you could do differently.

Can you post pics of the cracks and the cuts on the slide? An overly chopped slide will be more apt to crack than a stock one, but if this one was built by Infinity, I would say that they know what they are doing when it comes to cutting slides the right way.

[BillChunn]

Just out of curiosity, what powder are you using?

6.9 grains of Winchester AutoComp for the 9mm Major. When it was 38 Super, I was running IMR 4756 (don't remember the exact load but it comfortably made the old 175 power factor).

How many rounds through it?

Since it was not in my possesion 100% of the time, my best guess is 90,000 - 100,000. Possibly more. Possibly less.

As long as you have the gun sprung properly and are running good loads, (not too hot) then I am at a loss as to what you could do differently.

Can you post pics of the cracks and the cuts on the slide? An overly chopped slide will be more apt to crack than a stock one, but if this one was built by Infinity, I would say that they know what they are doing when it comes to cutting slides the right way.

The slide was lightened to shoot 9mm Major. There are 5 sets of serration cuts on the front.

BC

Edited March 19, 2013 by BillChunn

[latech15]

Was it tri-topped?

90-100k + cracked slide= cost of doing business. Get a new one and be proud it made it to 100k.

Guns, like cars, machines, and women; they wear out and have to be replaced.

[EkuJustice]

ya slide will crack eventually you got your use out of it

[gng4life]

Was it tri-topped?

90-100k + cracked slide= cost of doing business. Get a new one and be proud it made it to 100k.

Guns, like cars, machines, and women; they wear out and have to be replaced.

+1 (love the analogy!)

[BillChunn]

Was it tri-topped?

Yes, I believe so. See pictures in post #4.

90-100k + cracked slide= cost of doing business. Get a new one and be proud it made it to 100k.

Done. Sent Matt a text on Saturday when it happened and requested he put a replacement slide on order.

Guns, like cars, machines, and women; they wear out and have to be replaced.

Hopefully my wife doesn't read this forum....

BC

Edited March 19, 2013 by BillChunn

[BillChunn]

Is anybody using recoil buffers in 9 Major?

How about the Recoil Master that is basically a Gen 4 Glock double spring setup?

Good? Bad? Ugly?

BC

[latech15]

I don't use either.

[gng4life]

I don't use either.

+1 again...I swear I'm not stalking you

[lcs]

I have used shok buffers on all my 38s and 9 major guns with standard recoil rods. I acquired a used 9 Major Match Master with a low round count and use the STI Recoil Master.

Using 115 with HS6 and the Match Master is as soft/Flat shooting as any open gun I have had in the past. I never liked Recoil Masters before, but the Match Master is super nice with it.

[lcs]

I have to agree with other posters-90K to 100K out of gun is pretty good mileage.

[Rick88]

I know a guy who got his 2011 gun accurailed early in its life and now has over 200 k thru it and still going strong. He did replace the barrel at some point. On the other hand I have seen many cracked slides over the years some new guns with no cuts, maybe its just luck of the draw.

[Jaxshooter]

I have had several 9 mm major guns and have used True Blue and Silhouette powder in all of them. My loads are in the 170-172 PF range and I have not had a problem. Both powders burn clean (Silhouette is the cleaner of the two). My current load is 8.0 gr Silhouette with a MG 124 JHP or 124 CMJ at 1.165 OAL. My gun shows no sign of wear to the breech face or battering of the frame. I run a 9 lb variable recoil spring. Limcat Flashcat with 6 barrel holes plus comp.

[Koppi]

I think it is a spring problem. If you where to run a 12 to 14 lbs spring I doubt you would crack a slide.

[BillChunn]

I have had several 9 mm major guns and have used True Blue and Silhouette powder in all of them. My loads are in the 170-172 PF range and I have not had a problem. Both powders burn clean (Silhouette is the cleaner of the two). My current load is 8.0 gr Silhouette with a MG 124 JHP or 124 CMJ at 1.165 OAL. My gun shows no sign of wear to the breech face or battering of the frame. I run a 9 lb variable recoil spring. Limcat Flashcat with 6 barrel holes plus comp.

How many rounds do you have through it?

BC

[BillChunn]

I think it is a spring problem. If you where to run a 12 to 14 lbs spring I doubt you would crack a slide.

I believe Matt put a 9 or 10 pound spring in it. It is what he and his wife use in their 9 Major guns. I'll ask him later today.

Matt said he put a 8 pound spring in it.

BC

Edited March 20, 2013 by BillChunn

[latech15]

I think it is a spring problem. If you where to run a 12 to 14 lbs spring I doubt you would crack a slide.

If you run a 12-14lb spring the gun won't be nearly as flat as it should be. 8-9lbs is pretty much the standard in a 9mm open gun. That heavy of a spring will require a heavier load with more gas to make it remain flat, thereby accelerating the wear prematurely on lots of parts of the gun. Not to mention the shooter.

[Matt Cheely]

Slides on competition guns crack, it is what it is. Doing just a flat top instead of a tri-top can help, but they will still crack around the ejection port at some point.

I run 8lb springs, no buffers! Shortening the stroke on a 1911 just makes them less reliable.

[Albertl35]

Over the last year, I have seen at least 3 cracked slides and frames. Some more rounds than others but approximately in the 10-20k range. The only common factor is 9mm major and autocomp. Not sure if there is a resonance issue or an issue with slides.

[bonglee0507]

At this weekend's local match, the gun became noticeably harder to manually cycle at the "Make ready" command. It made it through the first two stages and then on the third (of four) it turned into a single shot. The slide would remain rearward and not return to battery. Had to grab the slide racker and force it forward for every shot.

The gun is about 10 years old. I had it built as a backup gun when my original broke at a match in upstate New York. The pair were in 38 Super and ran quite well for a number of years. I got out of the game and sold both guns then returned and bought this one back from the guy I sold it to.

Matt Cheely converted it to 9mm Major and am running 124 grain Montana Gold at a ~170 power factor.

The crack goes from the radius of the ejection port down to the bottom of the slide. It was not noticed immediately as it was behind the scope mount. There is another small crack that has started at the top of the breachface so basically this Infinity slide is toast. The gun is running a standard configuration recoil spring, reverse plug and guiderod. Pictures are in post #4 below.

My question is how to prevent this on the replacement slide?

Any and all suggestions will be appreciated.

Thanks,

BC

maybe the slide to frame fit is very tight man. i have seen this in over fitted guns

[OperationHitFactor]

10-20k a cracked slide is either a poorly fit barrel or problem in the metal. 90-100k crack everything was fit perfect and the metal was good, it was just time. Maybe... another 20K could have been squeezed out if it was not tri-topped, in 38 Super, with a slow powder "again maybe" however, this is debatable.

Shok Buffs = Flip a coin. I know smith's that swear by them and others that swear at them. My gunsmith swears by them and I flat out refuse to run one. Personally, I hate buffs, but in theory they do make sense. It was explained that take a steel wall hit it with a hammer then a hit in a different spot with a thin rubber mat in between. What happens?

Now another great gunsmith told me they are pointless because you could take two steel hammers and bang them together over and over for years. Both build guns that run for many many thousands of rounds 100%. So pick your poison.

[9X23Guy]

In my old gun I ran a 9 pound variable spring with a Dawson aluminum buffer. The aluminum buffer has all the advantages of using a buffer without most of the disadvantages. Just inspect it when cleaning and if its starting to mushroom out a little give it a few strokes with a hand file, done. I run a recoil master in my new gun but the two guns are very different.

[CocoBolo]

Well backup gun slide cracked at a Steel Match on Sunday a couple of weeks ago, it is a 9 major, formally 38 Super. My smith's cracked about a year ago, same exact cracks as mine, which is the same exact cracks as posters. At the TX open a friend of mines 38 Super cracked its slide. So I don't think it has a thing to do the with caliber. In these 3 we have a 10#, 9#, and an 8# recoil spring, no shock buffers. The round counts while SWAGS are 100k, 50k, 20k. The common factor STI slide, major pf, and Open Gun, all cut down to fighting weight.

While I am not a metalurgical exspert I bought a Caspian slide for a replacment, If it don't crack then I made the right choice. There is something about that little label that comes with it that says RC 40, I like, it has been hardness tested. Then again in a stock car a grade 8 bolt will break and a grade 5 bolt will streach, it is knowing which one to use where.