Semi auto advice needed

[aschler]

No, but when you use different parts from different manufacturers, it's a good place to start looking for the cause of the problem. You issue above is worse than belted mags that I have seen. I would look at different brass.

It was Nosler & Hornady, my only other choices are S&B (not available at the time) and Starline (not sure if they were available); I think Remington was still making 6.8 SPC brass at the time but I wasn't going to buy from them. After the problem was addressed I still had about 300 cases that seem to be holding up well so I will probably trash the barrel before I run out of brass.

I checked headspace when I assembled the upper but I wasn't checking case growth at the time; I used the method the die manufacturer recommended for setting up your sizer die at the time.

 

[cajun]

It was Nosler & Hornady, my only other choices are S&B (not available at the time) and Starline (not sure if they were available); I think Remington was still making 6.8 SPC brass at the time but I wasn't going to buy from them. After the problem was addressed I still had about 300 cases that seem to be holding up well so I will probably trash the barrel before I run out of brass.

I checked headspace when I assembled the upper but I wasn't checking case growth at the time; I used the method the die manufacturer recommended for setting up your sizer die at the time.

That last paragraph has bit a lot of people myself included. I now have a hornady headspace comparator and set up every sizing die with it. I consider a necessity for every reloader.

 

[Koda_]

Sorry should have specified COAL

agree with this if it's something close to max load…. If you have a load that is on the lower end of the load data so to speak, how is this a problem? I mean when you start a load for a rifle where would you start? Not sure what your post is saying really…

Its generally not a problem but I thought one had to full length size and use exactly the same components listed in the load data to assure saami chamber pressure listed in the load data?

 

[DarryH]

case sizing issue?? Usually I use small base dies for semi-autos, This takes brass back to basically factory dimensions. I have had several guns that will not share the same ammo just because of different chamber dimensions. Not sure these dies are available for .204 Ruger, Most often my bolt guns can share ammo if full length resized, but not always.

 

[Turpentine21]

I always thought were werent supposed to shoot handloads developed for one rifle, in a different rifle?

Depends. I can run loads for my smaller chambered Grendel in either. But the Loads developed for the larger chamber won't even fit in the smaller due to headspace.
Just like a factory load, we can load to a minimum set of specs that will work in most any rifle. It may not be the absolute most accurate but it will work.. But they have to be loaded to below minimum headspace requirements and i wouldn't want to make an all around load too hot.
I run 5.56 in any number 4-5 different rifles. But I know which one requires the smallest headspace number and I stay below that. These certainly aren't max loads. You can test and find loads that will be accurate enough in several rifles if you do so wisely. You also need to know which rifle has the shortest distance to the lands.
If I am after extreme accuracy, I'm going to brew up a load for that individual rifle. But if I just want a plinking or short distance hunting load that will give more than satisfactory results I can load a one size fits all that will be perfectly safe.

 

[Koda_]

Depends. I can run loads for my smaller chambered Grendel in either. But the Loads developed for the larger chamber won't even fit in the smaller due to headspace.
Just like a factory load, we can load to a minimum set of specs that will work in most any rifle. It may not be the absolute most accurate but it will work.. But they have to be loaded to below minimum headspace requirements and i wouldn't want to make an all around load too hot.
I run 5.56 in any number 4-5 different rifles. But I know which one requires the smallest headspace number and I stay below that. These certainly aren't max loads. You can test and find loads that will be accurate enough in several rifles if you do so wisely. You also need to know which rifle has the shortest distance to the lands.
If I am after extreme accuracy, I'm going to brew up a load for that individual rifle. But if I just want a plinking or short distance hunting load that will give more than satisfactory results I can load a one size fits all that will be perfectly safe.

I think you just confirmed my somewhat rhetorical question

 

[Turpentine21]

Checking headspace isn't a guarantee you won't be oversizing your brass. I had a rifle that passed a headspace check but still saw the case growth of 0.013" from my resizing die fully seated and 0.012" & 0.014" from unfired brass.

A rifle may be a pass on a headspace gauge but in order to keep from stretching or setting brass back too much we have to measure fired cases out of that rifle with a comparator then set your die to set those cases back 3-4 thousandths for an auto, 1.5 thousandths for a bolt from the number you got from your brass. The issue is that measurements from a different comparator will likely not be the same due to tool to tool variance. But you can certainly use your comparator to help make decisions. It's just that your comparator numbers may be meaningless to someone else.

 

[Turpentine21]

Every custom gas gun needs an adjustable gas block for this reason. I even had to drill a gas port a bit and choke it down with the block to get it to cycle.

I've been able to settle down a few guns with an H or h2 buffer with a non adjustable block, But the SLR adjustable block is one of the best things I ever did for my AR 10. I may have been lucky but the two Grendel barrels I bought from AA have had good headspace numbers and port size was perfect.
I have one older barrel that I'll not call the manufacturer name that I am convinced is marked as a type 2 barrel but actually reamed as a type 1. Headspace numbers compared to several Grendel's varies as much as +.010. It is hell on brass. I have been tempted to try a type 1 bolt and have it faced slightly to make it match so it doesn't stretch brass so much.

 

[nksmfamjp]

Checking headspace isn't a guarantee you won't be oversizing your brass. I had a rifle that passed a headspace check but still saw the case growth of 0.013" from my resizing die fully seated and 0.012" & 0.014" from unfired brass.

Can someone explain to how these 2 rifles have the same chambering, could both pass correct go/no-go gages and have 0.015" length difference? I'm making an assumption that the growth would all occur in the body.

i know about the issues of go/no go between brands, but that is a couple thou….not a mile. IMO, that AR needs the barrel gaged.

 

[Earnhardt]

Every custom gas gun needs an adjustable gas block for this reason. I even had to drill a gas port a bit and choke it down with the block to get it to cycle.

Yup...^^^^

 

[cajun]

Can someone explain to how these 2 rifles have the same chambering, could both pass correct go/no-go gages and have 0.015" length difference? I'm making an assumption that the growth would all occur in the body.

i know about the issues of go/no go between brands, but that is a couple thou….not a mile. IMO, that AR needs the

Can someone explain to how these 2 rifles have the same chambering, could both pass correct go/no-go gages and have 0.015" length difference? I'm making an assumption that the growth would all occur in the body.

i know about the issues of go/no go between brands, but that is a couple thou….not a mile. IMO, that AR needs the barrel gaged.

I think the problem with that one is there are 2 grendel chambers. One uses a 7.62x39 bolt. There is .010 difference in headspace. But, if you look at any chamber drawing there is a tolerance of .010. So if you have a max chamber and most sizing dies are set to min plus a little tolerance stacking you get a sizing die that will push the shoulder back .014. I've seen it. You can tell on the initial firing of new brass how much it grows if you have the hornady tool. This is why you should always measure and push the shoulders a min amount.

 

[Turpentine21]

Precisely, my first Grendel I did when I did not know as much about these things is within spec but at the very top of the range. My last personal build is at or very close to minimum. I have never had an issue with the larger one causing case head separation or splitting but after the 1st firing That brass only gets the shoulders bumped about 3 thousandths.
The last 5 or 6 I have built all has fired brass measuring within 3 thousandths of each other. The average for those is a full .008 less than brass fired in that first barrel.
My hopes are that I may find a bolt or make one that does not have as deep a face as the one that is on there now. Or possibly try a type 1 bolt and take a couple thousandths off the face. I don't shoot that gun much now. But it shoots very well with the right loads. I just have to be careful not to get loads mixed up.

 

[aschler]

Precisely, my first Grendel I did when I did not know as much about these things is within spec but at the very top of the range. My last personal build is at or very close to minimum. I have never had an issue with the larger one causing case head separation or splitting but after the 1st firing That brass only gets the shoulders bumped about 3 thousandths.
The last 5 or 6 I have built all has fired brass measuring within 3 thousandths of each other. The average for those is a full .008 less than brass fired in that first barrel.
My hopes are that I may find a bolt or make one that does not have as deep a face as the one that is on there now. Or possibly try a type 1 bolt and take a couple thousandths off the face. I don't shoot that gun much now. But it shoots very well with the right loads. I just have to be careful not to get loads mixed up.

I didn't even know you could oversize brass at the time. After a little research I started doing the same as you and didn't have any more problems.

 

[aschler]

I think the problem with that one is there are 2 grendel chambers. One uses a 7.62x39 bolt. There is .010 difference in headspace. But, if you look at any chamber drawing there is a tolerance of .010. So if you have a max chamber and most sizing dies are set to min plus a little tolerance stacking you get a sizing die that will push the shoulder back .014. I've seen it. You can tell on the initial firing of new brass how much it grows if you have the hornady tool. This is why you should always measure and push the shoulders a min amount.

This was actually in 6.8 SPC II. You don't have the issues with different bolts like with a Grendel but you do have multiple chambers that are similar. I also have a 6.8 ARP (supposed to be like 223 Wylde vs 5.56 Nato) that has an extremely short chamber but still passes the headspace check and produces brass 0.007 shorter than the SPC II. I've always just assumed they wanted brass than was very undersized since this was originally designed for the military since when with a minimum chamber you would get 0.006-0.008 case growth.