Short throat issue, rifle wont chamber anything with a COAL over 2.245

[Hawk518]

It would be better to get rid or fix a short throat rifle then to ever use it.

The issue was fixed and it is longer than original. The issue would not have even been if i only shot factory ammo until the ELD Match bullets came out. The barrel was manufactured before them and it shot the Hornady SST with no issues. The benefits of the throat at its present length is i can seat hand loads to just off the lands and have clearance in the mag.

[Hawk518]

It would be better on my eyes to get rid of the green text!

I changed the green in the original post for ya

[caleb90]

my hardened arms 20in barrel also has a short throat. factory hornady black just clears and chambers good. but in my hand loads using nosler custom comps the difference in orgive from the hornady heads. makes me have to load at 2.200 oal other wise the bullet will be jammed in the rifling.i was able to work around this issue by reducing my handloads and using a crono to work up my loads to an accurate load that matches book velocitys, im using about .5gr to 1gr less of powder to achieve the book velocitys and accuracy.

[TreeTopFlier]

This really seems to be a problem with this chamber. I had one that was replaced under warranty. Same thing, Sierra 120gr hpbt would jam in the lands at mag length.

I wonder if the "compound" throat is hard to get right because this problem seems to be epidemic.

I should also say the head space on this barrel was fine.
TTF

[FRB6.5]

This really seems to be a problem with this chamber. I had one that was replaced under warranty. Same thing, Sierra 120gr hpbt would jam in the lands at mag length.

I wonder if the "compound" throat is hard to get right because this problem seems to be epidemic.

I should also say the head space on this barrel was fine.
TTF

The chamber on that one was not in spec. Sadly there is at least one reamer maker who makes out of spec reamers and doesn't seem to care. Given some of the rough chambers I've seen outside of throating issues many barrel makers/finishers seem to use (or abuse) their reamers way past their usable life span. http://www.65grendel.com/forum/showthrea...asurements

[A5BLASTER]

This really seems to be a problem with this chamber. I had one that was replaced under warranty. Same thing, Sierra 120gr hpbt would jam in the lands at mag length.

I wonder if the "compound" throat is hard to get right because this problem seems to be epidemic.

I should also say the head space on this barrel was fine.
TTF

It's not the chamber are it's design.

It's company's useing questionable reamer's made by a few less then honest reamer makers or company's useing their reamer's past their working service lifespan. And some company's are just idiots and shouldn't be allowed to run a blinder much less a mechanical tool of any kind.

[Fess]

This really seems to be a problem with this chamber. I had one that was replaced under warranty. Same thing, Sierra 120gr hpbt would jam in the lands at mag length.

I wonder if the "compound" throat is hard to get right because this problem seems to be epidemic.

I should also say the head space on this barrel was fine.
TTF

Here is a link to see the Grendel's SAAMI chamber. http://www.65grendel.com/forum/showthrea...l-Drawings

The compound throat makes the Grendel unusually sensitive to reamer wear. Typical modern rifle chambers have a section of straight freebore before the angled throat. The walls of the freebore are parallel and the diameter is greater than the 0.264 diameter of the barrel's grooves. The tapered throat starts at the diameter of the smooth freebore and gets smaller, intersecting the base of the rifling and continuing until it is smaller than 0.256" diameter of the lands. The angle of taper varies from cartridge to cartridge, but often is commonly 1-1/2 degrees per side. The sides of the bullet can't touch any rifling until it is past the freebore. The .264 LBC and "Grendel II" chambers are like this.

The SAAMI Grendel chamber does not have typical freebore. Instead, its throat starts with a gentle 1/2 degree-per-side taper, then increases to 1-1/2 degrees-per-side. The starting diameter is again larger than the grooves, but the rifling begins somewhere before the taper steepens. Exactly how far down the barrel the rifling begins depends on the wear of the reamer. If the reamer is at max spec (0.2644 +0.002"), the rifling begins farther down the barrel, almost at the place where the taper angle increases. If the reamer is at the minimum spec (0.2644"), the rifling begins sooner. If the reamer is too worn, the rifling starts even sooner, giving the infamous "short chamber." The unusually shallow taper angle increases the movement of the intersection with the rifling due to a given amount of reamer wear when compared to that of a steeper taper angle.

In practical terms, with the SAAMI Grendel chamber, the distance to the beginning of the rifling is variable and can be very short, depending upon the condition of the reamer. With a "standard" chamber, the distance to the rifling still varies somewhat, but it is always longer than the freebore.

[TreeTopFlier]

It's not the chamber are it's design.

It's company's useing questionable reamer's made by a few less then honest reamer makers or company's useing their reamer's past their working service lifespan. And some company's are just idiots and shouldn't be allowed to run a blinder much less a mechanical tool of any kind.

I didnt say that very well. I meant chambering which to me means the entire chamber -> throat ->and leade angle(s). I dont doubt that everything stated above contributes to the problem, I am just noting that these same crappy barrel makers and reamer makers dont seem to have this problem as much with other cartridge chambers. I suspect that the throat design is a little trickier to get right and probably even harder if you're sloppy with your work.

[TreeTopFlier]

Here is a link to see the Grendel's SAAMI chamber. http://www.65grendel.com/forum/showthrea...l-Drawings

The compound throat makes the Grendel unusually sensitive to reamer wear. Typical modern rifle chambers have a section of straight freebore before the angled throat. The walls of the freebore are parallel and the diameter is greater than the 0.264 diameter of the barrel's grooves. The tapered throat starts at the diameter of the smooth freebore and gets smaller, intersecting the base of the rifling and continuing until it is smaller than 0.256" diameter of the lands. The angle of taper varies from cartridge to cartridge, but often is commonly 1-1/2 degrees per side. The sides of the bullet can't touch any rifling until it is past the freebore. The .264 LBC and "Grendel II" chambers are like this.

The SAAMI Grendel chamber does not have typical freebore. Instead, its throat starts with a gentle 1/2 degree-per-side taper, then increases to 1-1/2 degrees-per-side. The starting diameter is again larger than the grooves, but the rifling begins somewhere before the taper steepens. Exactly how far down the barrel the rifling begins depends on the wear of the reamer. If the reamer is at max spec (0.2644 +0.002"), the rifling begins farther down the barrel, almost at the place where the taper angle increases. If the reamer is at the minimum spec (0.2644"), the rifling begins sooner. If the reamer is too worn, the rifling starts even sooner, giving the infamous "short chamber." The unusually shallow taper angle increases the movement of the intersection with the rifling due to a given amount of reamer wear when compared to that of a steeper taper angle.

In practical terms, with the SAAMI Grendel chamber, the distance to the beginning of the rifling is variable and can be very short, depending upon the condition of the reamer. With a "standard" chamber, the distance to the rifling still varies somewhat, but it is always longer than the freebore.

This makes perfect sense, thanks for taking the time to jot that down. If done correctly you can really see why this would be a very accurate cartridge.