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Anyone running into problems with certain types of ammo when using a SL8 fitted with the US made bolt head?

Went out to the range today and shot my SL8 with two types of ammo, some Norinco .223 and some Yugo (Hansen) M855 ammo, which is listed as .223 and 5.56mm. 100% success with the two boxes of Norinco .223. 100% failure with 3/3 rounds of the other ammo. The first two rounds fed, fired, and ejected, but didn't cycle the action far enough to pick up the next round. The third round jammed the bolt during feeding and I had to pound on the charging handle to get it out. Saved the round, which didn't appear to be dented or damaged in any way and did some testing with it later at home.

I tried chambering the round in my SIG 556 and an AR, and the round chambered fine. I tried a second US made bolt in my SL8 and it jammed exactly like the first one. I then tried my original SL8-1 bolt and it chambered the round fine.

BUT, the SL8-1 bolt didn't have the ejector or extractor installed, and I don't know if that made the difference.

I'm thinking that there is a headspacing issue with the US made bolts with certain types of ammo and the fact that it happened with two US made bolts implies that it could be generic. The hangup seems to be when the bolt rotates to lock in the barrel extension. Anyone using the US bolts running into similar problems?

I've considered the potential that the chamber is really .223 and a 5.56 round could be longer and causing the problem, but another recent thread here seems to imply that the chamber is 5.56 even though the gun is stamped .223 (the manual says you can use .223 or 5.56x45). The fact that the original SL8 bolt worked also implies that the round in question can fit in the chamber, so it's not a chamber problem.

I suspect the easy answer is to just get a G36 bolt, but I've got parts count issues if I do that.

Any suggestions (other than get a G36 bolt) or similar experiences? TIA.
 

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you have to take the extractor and plunger from the sl8 bolt and put it on the double stack usa g36 bolt other wise it won't function properly also if you have the usa piston you have to take the gas rings of the original and put it on the usa piston for it to cycle. and if you are you using a single stack sl8 original bolt with a double stack mag it's not going to work but misfeed becuase it can only feed from one side of the mag.
 

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5.56 vs .223

Just read an article that said never shoot military 5.56 in a Remington .223 rifle. Case is different and the powder charge is different from what the SL8 was built for. Anyone here who says that they are interchangable is just spouting internet bull. 5.56 in a .223 rifle is unsafe.
 

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Discussion Starter #4
you have to take the extractor and plunger from the sl8 bolt and put it on the double stack usa g36 bolt other wise it won't function properly also if you have the usa piston you have to take the gas rings of the original and put it on the usa piston for it to cycle. and if you are you using a single stack sl8 original bolt with a double stack mag it's not going to work but misfeed becuase it can only feed from one side of the mag.
Thanks, but I think you misunderstood my problem. I do have the extractor and ejector on the two US bolts that I tried and understand that differences between the single stack SL8 bolt and the bolts made to work with double stack mags. The issue I'm having appears to be headspacing with the US bolts and the second type of ammo that I tried.
 

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well then hk is lying to everyone then, because if you read their manual for the sl8 and g36 it is compatible with both, i would think hk with all their years of firearm experience would know what they're talking about.
 

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I knew someone would say it (Rockstar)

The latest issue of the National Rifleman has an four page article on this issue.

SAAMI the Sporting Arms and Ammunition Manufacturers Institute says using 5.56 x 45 in a Remington .223 caliber rifle is "unsafe" for the reasons I mentioned above.

.223 can be used in a 5.56 x 45 but not the other way around. Now, since the SL8 is based on a military rifle, the G36 then maybe this applies but I think the problems you are having are ammunition related, not bolt.

Rockstar: HK does not care if you split your cases and you can shoot .380's in a 9mm but that dont make it right.
 

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i think hk cares enough about something that they put in print because that is makes it a legal issue where if there were a problem and it was because they failed to mention something there could be lawsuits, they could be liable, so for them to stand behind something enough where they would put it in their manual, then they're putting a documented gaurantee that their product is going to function they way they say it will. they always put a note that they can't warranty it if you're doing something against what they state, but they clearly state that it'll work just fine with both. i see what you're saying but i disagree that they don't care. if they didn't care they wouldn't put it in print that you can do something or not, that puts a lot of accountability on them. it's not like it's word of mouth or a rumor that someone said hk says it's ok. it's there for everyone to see, everyone who buys their rifle is going to read the same thing and follow all the guidelines they provide. it's their rifle, they designed it tested, repair, built. i trust it.
 

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tom bostic welds up the lug on sl8 ones to make it work for double stack, he does it for 35 bucks.
 

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Do you know how to swap the gas rings on TN piston?
Would appreciate your advice or a link to instructions (if exist).
Thank you
 

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When I first got my SL8-1/G36 conversion (I bought it already converted, used) it would frequnetly jam on a live round with the bolt being locked up (forward). Once at the range, it got so jammed that no amount of hand pounding on the bolt lever would get it to retract, so I was stuck with a cocked rifle with a live round in the chamber. It took an armorer to get the round safely ejected.

At first I thought it was junky ammo, bad mag, etc. At that time it still had the AR15 mag adaptor (later swapped out for the G36 mag well). I tried different mags, different ammo, different lubes, etc. to know avail. It would shoot a few, the lock up in the forward position.

A gunsmith suspected that the lugs on the bolt might be a tiny bit out of spec, causing a lockup under the right conditions. I was going to replace the bolt head with a real G36 unit, but that would have messed my parts count. The gunsmith suggested trying to fix the existing bolt instead. He machined off a small amount from the lugs. He test fired it without any failures.
 

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Case is different and the powder charge is different from what the SL8 was built for. Anyone here who says that they are interchangable is just spouting internet bull. 5.56 in a .223 rifle is unsafe.
Except it's not a .223 rifle. The G36 (and SL8 by default) is a 5.56 rifle. They put .223 on the side to appease the dopes in Washington so it would be firing a "sporting" cartridge, not because it's unsafe to run 5.56.

You are right about the "internet bull" though! :D

Back to the OP, it's definitely the bolt head. You have to have it tweaked, contact eltee. I like that BTW that's what I used to be in the Navy.
 

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Discussion Starter #15
Thanks. So where would the bolt lugs have to be machined? I'm assuming that you would have to shave a little off the rear of the lugs? Anyone know who would do that sort of stuff?
 

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I installed the US bolt and test-fired it with the single stack SL8 mag, and had jam after jam. I had initially cycled dummy rounds through the rifle to make sure the extractor/ejector were functioning properly, which they where. I went through 5 rounds in a row using the dummys. But like I said, with only two live rounds, the rifle jammed after firing. It was as if the bolt wasn't traveling far enough back to completely eject the spent casing. FYI I was making sure the rifle worked partway through my G36 conversion so that is why I only had the bolt installed and not all my compliance parts. I'd rather test it in increments than slap together the whole thing THEN fire it and debug any issues...

Am I an idiot for shooting the rifle with the single-stack mag & double-stack US bolt? My theory is the extra lug is dragging just enough on the top of the mag to slow the carrier down and cause a FTE and subsequent jam. I have the AR magwell conversion ordered but it is back ordered right now. I am willing to bet it would be just fine w/ the AR magwell but I need some opinions.
 

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I have shot my rifle with a US-made bolt head (TN) and a factory single-stack SL8 mags.
Not a single jam.
If you are running a US-made gas piston, have you rmemebered to put the compression rings on it from the HK piston? I know it sounds stupid, but I made that particular mistake and spent few ours wondering why my expensive conversion wouldn't function right.
 

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I have shot my rifle with a US-made bolt head (TN) and a factory single-stack SL8 mags.
Not a single jam.
If you are running a US-made gas piston, have you rmemebered to put the compression rings on it from the HK piston? I know it sounds stupid, but I made that particular mistake and spent few ours wondering why my expensive conversion wouldn't function right.
The rifle is original except for the US-bolt. This is an SL8-6. So no, it wouldn't be the gas piston. When cycling the dummy rounds maually they are ejected just as quickly and correctly as with the german bolt. The extractor can be depressed and moves with finger pressure, and the ejector button moves freely when enough pressure is applied. I am at a loss as to why the rifle is jamming. I'm firing remington brass-cased ammo and had no problems w/ this ammo when the rifle was "original".

Also - I loaded the mag with only ONE round and fired it, repeating this process five times. Only one out of the five FTE.

I can't look now but I am thinking the recoil buffer might be missing since I was swapping the parts between the HDPS block and SL8 stock, but I am 95% sure it is there. I'm just trying to think of any boneheaded things I could have done and that crossed my mind just now. Man that would be dumb but like I said, I have no reason to believe it was missing. Anyone think that would cause this behavior?
 
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