Problems with my new build - Anyone have headspace gauges?

[txgunner00]

Primers aren't pierced or cratered. They were blown out of the case.

[bigbear_98]

Academy in cedar park and off 183/duval usually has factory sst if you want to get a box and try them. Or I can meet you somewhere and give you a couple rounds to try.

Eta
I also have a hornady gauge and some loose amax and sst. We could measure your throat depth.

[txgunner00]

I have a COL gauge but I'm not having any luck finding factory ammo in stock. The Academys are currently out. I appreciate the offer. I might have to take you up on it.

[bigbear_98]

I can tell you now, I measured 10 factory sst rounds. They averaged 2.245coal. Longest was 2.247, shortest was 2.244.

Are you measuring your chamber with 123gr sst?

[txgunner00]

Yes. Just looked at my book. I measured 6 projos with my COL gauge. Low was 2.216, high was 2.218. The load length I used was actually 2.215.

I tracked down some 123 Lapua ammo across town but no 123 SST yet.

[bigbear_98]

If you already measured a clean barrel as being short, what are you going to do with factory loads that you know are longer than your chamber?

[JASmith]

If you already measured a clean barrel as being short, what are you going to do with factory loads that you know are longer than your chamber?

Many of us view the check with factory loads as a necessary step in verifying that the throat needs work. They are the closest thing we have to a throat gauge.

[bigbear_98]

Many of us view the check with factory loads as a necessary step in verifying that the throat needs work. They are the closest thing we have to a throat gauge.

Make up a couple dummy rounds to between coal of 2.244 and 2.247?

Txgunner. I still have a couple rounds I'll give you but hate to see you waste good ammo....;-)

[Drifter]

... 27.6 grains of 8208 behind a 123 SST, Hornady brass...

... I measured 6 projos with my COL gauge. Low was 2.216, high was 2.218. The load length I used was actually 2.215.

Aside from a potential headspace issue, it's possible that the combination of the bullet being seated at or very near the lands, as well as deeply into the case, could contribute to excessive pressure. Though your charge of 8208 is below listed max, it may be different in this particular situation.

[txgunner00]

Could be. I plan on running some more tests this weekend. I have some 100 Amaxes on hand. It might turn out that I can only run short bullets in this barrel.

[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.

[ATTACH=CONFIG]5417[/ATTACH][ATTACH=CONFIG]5414[/ATTACH][ATTACH=CONFIG]5415[/ATTACH][ATTACH=CONFIG]5416[/ATTACH][ATTACH=CONFIG]5413[/ATTACH]

[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/65...o-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?