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  #16  
Old 07-11-2020, 08:58 PM
carbineone

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Not a bunch more shooting, but did run another mag through it today, No Kaboom yet and all fired cases look great yet.
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  #17  
Old 07-12-2020, 04:45 PM
rc.

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Data for 10/22 Bolt Weight

I too am curious what weight bolt and handle that Marlin used in the 717.

I have rebuilt a 17 hm2 Ruger 10/22 using a green mountain 96/22 barrel and heavy bolt handle. I had played with this combination on an AMT action some years ago but it was heavy and not all that accurate in a 10/22 Wood stock I had sanded out for a .92 barrel.

For my "new build" I got more serious with the project. I bought a Hogue Standard barrel channel stock and chose to convert one of my lighter Ruger 10/22 rifles to mach 2. I am waiting on a match bolt with pinned firing pin. I tried the conversion with the factory Ruger Bolt and got some split rims and one kaboom with this particular bolt using Eley ammo. Some cases showed ballooned heads while others looked perfectly fine. Accuracy is running 1 to 1.5 inches at 50 yards so much less consistent than I would like but many times shots are touching so I think the potential is there if I can calm down the action. Bedding is better in the hogue stock but the thin forward section of the barrel is still free floating.

Here are some reference bolt and charging assembly weights reposted from my bolt weight thread.

Stainless AMT bolt with the BB firing pin mod 173 grams.
2007Ruger bright polished bolt assembly 183 grams
Another old style polished bolt weighed 182 grams
Recent complete cast 10/22 bolt 179 grams.


PC Titanium Charging handle, rod and spring 19 grams total.
AMT stainless charging assembly 24 grams total.
Ruger blued charging assembly 23 grams total.
Kidd "7.62 pattern" Stainless Charging handle, rod and spring 31 grams.
Kidd Ring Pattern Stainless Charging handle, rod and spring 31 grams.
Aftermarket Heavy Bolt Handle assembly 78 grams

My former HM2 build using the AMT stainless bolt and heavy handle had a combined weight of about 251 grams. My current build with the Ruger bolt about 261 grams.


I never had any KaBooms with this first combination. One of the cases I examined yesterday using the Ruger bolt split right where the firing pin crushed the edge of the case. It seems that too sharp a firing pin can cause trouble with the hm2. This bolt never had a blow out in 22 LR. The other failure I experienced was a near complete separation of the head from the case. I did not notice any complete separation that left anything in the chamber.

Still waiting on a bolt assembly with pinned firing pin. I have a kidd extra power spring available but will have to grind the heavy bolt handle guide rod to replace the current action spring for my build. I don't know if the Kidd spring would be am improvement. Can someone tell me what "standard" spring weight is for a Ruger 10/22? What is the heaviest spring available for a mach 2 build? So far I really like the way this build is turning out and hoping I can work out the issues so I can rely on it to work safely. The local squirrels already don't like it very much.
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  #18  
Old 07-18-2020, 10:52 AM
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Quote:
Originally Posted by carbineone View Post
So for those who have first hand experience. What is the real scoop on the Marlin 717 Mach 2 exploding Rifles? I have one coming Friday or so. Was it early ammunition production problems? The Rifle itself? Or maybe both?

The one I bought was purchased new by the owner. He fired a full mag through it fine. Loaded a second mag and had a Kaboom on the third round. Breaking a small piece out of the trigger guard. Put it away and never shot it again before selling it to me.


Anyway feel free to help with any useful input and first hand experience you have with the Marlin 717. Thanks
The issue with exploding 17 caliber blowback semiautos is not confined to the Marlin 717. It's a fundamental design problem.

Because of the tiny bore, pressure drops slowly as the bullet moves down the barrel. If the bolt starts to move even a little bit before the bullet has left the barrel, the pressure is still high enough to rupture the unsupported case and KABOOM! The window of safety is very narrow. Some guns fit right in and are less likely to KABOOM. But if the tolerances on your gun stack up just a bit on the edge of the window and you get a round that's just a bit higher pressure than normal, KABOOM!

It's also possible for dirt to accumulate in the chamber and cause a KABOOM because it prevents the bolt from closing completely. It is important to realize that this is only ONE cause of KABOOMs, not the ONLY cause. It is entirely possible to get a KABOOM with a pristine gun. I once had a customer's gun blow up on the third shot ever on an immaculate barrel. Regular cleaning will not eliminate KABOOMs.

The only way to prevent KABOOMs is to use a bolt action or a delayed action such as the Savage A17. Life is too short to deal with guns that blow up.
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  #19  
Old 07-19-2020, 09:36 AM
carbineone

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I have no problem dealing with the dangers of the 17 Mach2 round. Now a 30-06. I may worry more. I do not think the Kabooms that have happened come from a out of battery discharge or a dirty chamber either. I do not even think it will fire when the bolt is not completely in battery. Or atleast from my observations. I think it could happen because the bolt opens to soon, before pressure is minimized. But to me that does not exactly make a lot of sense either. I find it hard to believe that at the instance of firing there could be much pressure left in the case or the chamber end.

I really believe it is more related to the early defective ammo when the round first came out giving these early semi Rifles a bad rap.. People were finding case that were presplit so to speak in the early stages of the rounds development. I think they also found a way to anneal the cases and came up with better quality control. I think early on they were also using a non rimfire powder charge in these little rounds. I think they changed back to a regular 22 rimfire powder.

Mine does not scare me at all as far as safety. What does concern me about shooting it alot. If it would happen. I would be more concerned that Firearm would sustain damage than myself,LOL Especially to the stock. I would never find another original. I would have to restock it with a Boyds 795 stock.

I know there are not alot of these semi auto Mach 2 Rifles out there. But I have read the Marlins that are out there yet these days. I have not seen anyone claim a verifiable Kaboom in recent years. Kinda the opposite. The ones that are out there. They claim to not have had a problem ever after many many rounds.

I have 500 rounds for it. But will likely never shoot 100 of those..I may buy a 917 Mach 2 Bolt Marlin also though.

How many years ago did the customers Rifle kaboom?

I cannot buy a Savage. But I have read about the delayed blowback action they have. But even with that system. I wander if you put the old defective pre split cases in those, if they would also have a occasional Kaboom too. I bet the answer is yes.Thanks

Last edited by carbineone; 07-19-2020 at 09:41 AM.
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  #20  
Old 07-19-2020, 01:16 PM
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ss monte

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I fired a few rounds of 17 pmc out of mine yesterday with no problems. They fed and ejected just fine. I think it was early ammo as well, but I'm still going to keep my chamber clean and the extra power recoil spring gives me piece of mind as well. The only rounds I have seen split are early production.
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  #21  
Old 07-20-2020, 12:41 PM
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Quote:
Originally Posted by carbineone View Post
I think it could happen because the bolt opens to soon, before pressure is minimized. But to me that does not exactly make a lot of sense either. I find it hard to believe that at the instance of firing there could be much pressure left in the case or the chamber end.
Because of the tiny bore, pressure does not drop nearly as quickly as with a 22, which has a bore the size of the OD of the case.

Quote:
Originally Posted by carbineone View Post
I really believe it is more related to the early defective ammo when the round first came out giving these early semi Rifles a bad rap.. People were finding case that were presplit so to speak in the early stages of the rounds development. I think they also found a way to anneal the cases and came up with better quality control. I think early on they were also using a non rimfire powder charge in these little rounds. I think they changed back to a regular 22 rimfire powder.
IIRC, the early ammo had splits in the neck. That doesn't explain why cases bulge / blow out at the rim.

Got any evidence about the powder?
Quote:
Originally Posted by carbineone View Post
I have not seen anyone claim a verifiable Kaboom in recent years. Kinda the opposite. The ones that are out there. They claim to not have had a problem ever after many many rounds.
As I said above, there is a narrow window of safety and some guns fit in it. The ones that don't have been retired / rebarreled.
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  #22  
Old 07-20-2020, 02:13 PM
carbineone

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Did not think I was on trial,LOL But the powder change I read about was only told to me by someone with a connection to Hornandy, and others around the internet that have heard the same thing. Take it like anything on the Net, believe it or disbelieve it. Up to the recipient.

Show me evidence of a split case at the neck from a Marlin 717 using newer made ammo?. If you have found evidence please share it too.
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  #23  
Old 07-20-2020, 11:47 PM
colonelhogan44
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My personal theory (no evidence other than intuition having working in engineering) is that the new production ammo that finally started being made available after the great 22lr panic of 2008-2015 or whatever is de-rated enough to widen that "narrow window" out to cover 99.9% of blowback semi-autos of old.

The guns were "in the wild" and couldn't be broght back, so rather than deal with the occasional call from someone who blew up a gun blaming the ammo, they just dropped the loads back to around 2000 fps from 2150+. I still have a decent stash of old ammo which will be bolt gun only. I'd prefer the 2000fps de-rated ammo across the board if it allows for the 17hm2 ARs to work!

When was the last documented rim blow-out with ammo made in the last year or so? I've not heard of one reported.
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  #24  
Old 07-22-2020, 09:53 AM
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Originally Posted by carbineone View Post
Did not think I was on trial,LOL But the powder change I read about was only told to me by someone with a connection to Hornandy, and others around the internet that have heard the same thing. Take it like anything on the Net, believe it or disbelieve it. Up to the recipient.

Show me evidence of a split case at the neck from a Marlin 717 using newer made ammo?. If you have found evidence please share it too.
Perhaps "evidence" was a poor choice of words. I was looking for a source or citation.

I don't have any evidence of cases splitting at the neck with newer ammo, because it appears that problem has been solved. However, I don't think that is going to solve the KABOOM problem, because KABOOMs split the case at the base, not the neck.
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  #25  
Old 07-22-2020, 04:48 PM
carbineone

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Thanks

The two year old Honandy V max I have here is is stated as 2100 FPS on the box. I also called Hornandy. They are almost next door to me about 50 miles away. They did admit to early cases splitting and being defective. But said the line was greatly improved in recent years. He did not go into what exactly was done. But did say the problems have been addressed. He also said they will replace any 17M2 under ten years old if you think it defective. But no earlier than that.

I did find an older post too, that shows more all alleged problems encountered with the early 17 M2 rounds. Heres a pic of just how bad the early production of this round was. These were early Hornandy rounds I believe.

That could surely contribute to the big bang maybe if the bullets are falling into the case as they get chambered.
Attached Images
File Type: jpg mach 2.jpg (228.9 KB, 5 views)

Last edited by carbineone; 07-22-2020 at 06:31 PM.
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  #26  
Old 07-27-2020, 07:53 PM
carbineone

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SS Monte. What spring did you with? One from a aftermarket 795?

Just a sidenote. Red River reloading has 17M2 ammo in stock at a pretty good price. I think it cost me just under 80.00 for 500 rounds shipped.
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  #27  
Old 07-30-2020, 08:45 PM
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Yes, it was the mcarbo hyper velocity recoil spring for a model 60/795. The factory spring in the 717 is the exact same part number as a 60/795. It's a pain in the %%%%% to change, just like all these pesky recoil springs in Marlin's, but it is definitely stiffer with a little bigger wire. I've shot both 17m2 & 17 PMC/Aguila in it. No problems other than split necks on the 17m2 but this ammo is pretty old. I'll try to find some newer ammo and try it to see if it splits.
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  #28  
Old 07-30-2020, 09:46 PM
carbineone

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Thanks, you happen to know if the 795 shares the same buffer as the 717? I of course cannot find a buffer specific to the 717. Cannot find much of anything as a matter of fact for the 717..

I know well as I am a Marlin Fanatic about the pain in the butt recoil spring. But I am pretty well versed in them by now to do it correctly no. I kinked one long ago, but have learned since,LOL
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  #29  
Old 08-01-2020, 06:44 PM
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The 795 uses buffer part number 407182. The 717 uses part number 407007. If I had a 795 buffer to compare. with I would check them out, but I don't. I included the part numbers for the 717

Last edited by ss monte; 08-01-2020 at 06:49 PM.
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  #30  
Old 08-02-2020, 02:10 PM
carbineone

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Could I bother once more with a recoil spring question. What number does it show for a 795 recoil spring? Thanks

Edit: I think I found a number that shows the same recoil spring number for the 60, papoose, 795 to be the same as the 717. I am asking because I ordered a Macarbo extra power spring for a 795, to use in my 717M2. Looks like the 795 factory is around a 14 pound. The Mcarbo aftermarket 795 says right at a 18 pound spring. . I am thinking a extra power spring sure cannot hurt in the 717M2.

I pulled my 717 buffer out. It appears they used the same style as the 795. But the 717 one looks to be beefier, thicker,fatter so to speak..

It may help others if you would take the time to list the 795 part numbers if you have those too. Well to me anyway,LOL

Thanks for helping out. I appreciate it

Last edited by carbineone; 08-02-2020 at 02:29 PM.
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