Problems with my new build - Anyone have headspace gauges?

[BjornF16]

txgunner00...did you check headspace yet?

[txgunner00]

Gauges came today and just got done checking the AA bolt and the one that came with it. They are snug on the go gauge but fully lock with just 2 fingers.

Thanks again for sending them to me.

[txgunner00]

I pulled the barrel and remeasured the COL. I selected 10 - 123 SSTs and got an average of 2.226 (2.224-2.228). Those same 10 bullets averaged 2.302 in my Satern barrel with a true Grendel chamber.

I've made some attempts to contact several vendors that produce their own Grendel barrels to get some ideas of what I might be able to do with this barrel but haven't had any luck. At this point I don't know if the throat is just too short or if it's a combination of that and something else. Considering it's chrome lined I doubt it can be re-reamed but I don't know for sure. I wonder if honing or lapping could help? Any ideas?

[Variable]

I don't know. That is kind of the "worst case" scenario of a sort. Dumb question time: Is your throat and neck spotless in that chamber? Any chance there is some kind of crud hiding in it? Very close visual inspection possible since you already pulled it? Just flinging wild hopes here...

I guess I need to go check my spare 10.5" now too..... {gets nervous and shudders....}

[txgunner00]

Here's an attempt at some throat pictures.

IMAG0133_1.jpgIMAG0148.jpgIMAG0143_1.jpgIMAG0125_1.jpgIMAG0123.jpg

[Variable]

I went and dug through the gun room (looking like an explosion in a "Hoarders" episode... Uggh) until I came up with an AA bolt, a round of factory Amax, and the 10.5" barrel I got off gunbroker.



I got the bolt closed in the extension with the Amax round in the chamber, but it was a real bear to close it by hand. I tried a couple more with the same result. I don't know how much of the difficulty is from my lack of leverage and the resistance of the ejector vs. the interaction of the cartridge with the chamber.

I do notice that after chambering the Amax round in that barrel there is a shiny spot on one side of the bullet each time. It did it to every one I chambered by hand. That might be the ejector doing it though.





ETA: The more I think about it, the shiny spot is probably caused by the ejector pushing the round hard to the side while I'm manipulating the bolt.

[JASmith]

Variable, it looks like factory AMAX is happy with your chamber!

Bill Alexander posted (in another thread) that we should see no more than a 'light' kiss by the rifling when a factory load is chambered in a minimum spec chamber.

The only hiccup I have with that standard is that I am sure that your notion of 'light kiss' is different than mine.

In any event, that burnishing almost certainly meets the standard, regardless of the cause.

[txgunner00]

Most of the SST loads I have seated at mag length won't allow the bolt to lock up at all.

[txgunner00]

http://illirianengineeringc.ipage.com/65mm--68mm-pcc-pics-video-clips-charts-load-data-email-80-build-info-etc.html

I came across this page while doing some research on this matter and I thought I would share. Good info & pictures.

[jurassic]

I have the same barrel, I'll have to check it out before I put money in it. Does a factory loaded round drop in and out of the chamber?

[txgunner00]

I have not been able to get my hands on factory ammo but I made some SST dummy rounds with a COL of 2.244-2.247 per bigbear_98's measurements. I used AA and Hornady brass and checked all of them in a case gauge. I couldn't even force the bolt to lock by hand. This is one that I marked with sharpie. As you can see, I had to knock it back out with a brass rod.

IMAG0156_1.jpg

All of these dummy rounds chamber and extract freely in my Satern barrel with no marking throat marking whatsoever.

[PigOPs]

I have the same barrel, I'll have to check it out before I put money in it. Does a factory loaded round drop in and out of the chamber?

I too have the same barrel and it's perfect. I think txgunner may have a lemon!

[txgunner00]

I just checked COL with 123 Aamax bullets and got completely different results than the SSTs. Average was 2.256" (2.252-2.259).

This is a pic of dummy rounds seated to 2.258-2.260

IMAG0164_1.jpg

They had to be lightly tapped out with a rod.

This is the same rounds bumped back to 2.245-2.247

IMAG0162_1.jpg

These came out by lightly taping the barrel on the bench.

The both the SSTs and Amaxes seat at similar depths with similar settings on my seating die but the canalure makes them drastically different in terms of contacting the leade & rifling.

Amaxes may work better but wanted to tune this upper with SSTs for hunting. Plus I have a ton of them already and only a partial box of Amaxes

This is annoying.

[txgunner00]

I too have the same barrel and it's perfect. I think txgunner may have a lemon!

Looks that way. To add to the aggravation the business I bought it from won't respond at all. Just my luck...

[jurassic]

Looks that way. To add to the aggravation the business I bought it from won't respond at all. Just my luck...

Did you buy from RedX? I would give them a few days if you emailed them today, it is the weekend. I'm sure if you have a problem they will help you out.