6.5 Throating Reamer

[Clod Stomper]

[ss355]

I'm interested to hear responses on this one. Over the weekend I tried some quick-and-dirty checks on OAL to reach the lands in my LBC 264-chambered barrel, and using the big three 123 grn pills (Amax, Sierra, Lapua) I had what seemed to me as excessively long OALs. Nothing even close to mag length worked, though I don't have my numbers with me. Maybe my testing method is suspect--loading bullets long, smoking the bullet over a candle, and then hand feeding into chamber.

[sneaky one]

Clod, on the last forum Peashooter had what sounds like the same issue, no leade, no throat, it didn't get cut. He did a chamber - throat casting and the bbl. wasn't finished. He couldn't load anything. He said he bought a different bbl. which cured the problem. He claimed AA wouldn't help, but who knows. Call and ask them.

[bwaites]

Wait, though. 3 barrels with the same issue, from 2 different manufacturers?

Somethings up with that.

Have you tried factory loads? All those bullets tend towards the blunt side, but I've loaded the Sierras to 2.22-2.23 without issues. The Vmax is just a weird bullet, more conical than the others.

[Clod Stomper]

No, I have yet to fire a single factory Grendel round. I'm frugal that way.

I really don't think it's an issue with the barrel being manufactured improperly. It's just the way they're made. I really didn't want to start a thread about the design itself. I probably should have simply asked if anyone has cut more freebore in their Grendel and what were the results.

I don't have my notes in front of me, but I don't think I have loaded the SMKs that short. Although I did seat some deeper after finding they were too long. I'll have to measure those again.

Like I first posted, I'm not a benchrest shooter. I just want to be able to load to mag length and go. Don't get me wrong, I love accuracy, and I still want to be able to hit a 20" target out to 600 yards. But I'd at least like to know that if it fits in the mag, it'll fit in the chamber.

Of course I realize that cutting the throat will void any warranty. I'll live with that.

Or should I just keep seating bullets deeper until the throat gets worn on its own?

Thanks,

Will

P.S. On a side note, I fired the V-Maxes despite them being in the lands. Over 28 grains of 8208 XBR, they clocked 2700 fps from a 18.5" barrel. That was in Winchester fireformed cases. I only loaded three and haven't yet tried increasing the charge. That may be on hold until I find the proper seating depth. Like bwaites said, they are a weird little bullet. I can't seat them to the 2.23" as listed on the Hodgdon site. Between seating them deeper and the limited capacity of the fireformed case, I may not get much more powder in there. We'll see.

[Airhog]

Clod Stomper, I have not had issue with the chamber, but I have had issue with some ammunition. As Bwaites I'm sure will back me up on this the first round of Hornady 123grain A-Max was just a little out of spec. Causing them to stick in the chamber. The Lot that I had issue with was last 3 digits 669. I had considered doing the same as you on reaming the chamber just to make sure that I never had a malfunction in relation to that again, but I chickened out. My grendel is shooting really well and I hate to screw it up. That is 4 rounds at 100 yards with the 123 grain Hornady A-Max factory ammo. Don't pay any attention to that one on the left. That one is all my fault and I knew when I did it.
DCP_1457.jpg

[pinzgauer]

Like I first posted, I'm not a benchrest shooter. I just want to be able to load to mag length and go.

Outside of .223 / 5.56, I'm not sure you can safely do this on any of the AR-15 alternate calibers.

IE: You really need to learn to measure the right seating depth for your rifle. LR1995 has documented the poor man's loc & load. I used a dowel or cleaning rod of all things to get me close. There are multiple methods that will work.

I don't believe you have three rifles with unfinished throats, so it'd be worth confirming and takes 5-10 minutes max.

Once you do it, that becomes your standard seating depth. With three rifles, you'll have to compromise a bit if they have different throats. Both of mine are AA or AA licensed reamers, so the throat variance is so small it's not worth sweating.

I, like you, have been reloading decades. But not for AR-15's, and I have to say when you are pushing the envelop with grendel, spc, etc, you have to pay more attention with the gas guns. Bolt actions, just not an issue. The mags are long enough, the leverage when closing the bolt is high enough that it's almost impossible to seat them too long. I think they also tend to have different throats. (I'm sure there are bolt guns that are pickier with throats, but it's not your typical rack model 70/700/77/110.

I'll also say that there are dimensional constraints with the Grendel & similar that lead some bullets to have problems where others do not. The 123g SMK was problematic for me, as were 120g AMAX's. The 120g SMK and 123g AMAX's have been fine. As have Speer 120g Hotcores. No surprise on the 123g AMAX, as it was largely designed for the Grendel. Or at least with it in mind.

[Malchira]

You really need to learn to measure the right seating depth for your rifle.

PG is spot-on. I use a Sinclair Action Comparator, and have measurements (in my rifle, obviously) for two of the bullets you listed. The 120g SMK and 120g Hot-Cor both have configurations (shorter ogives, or tip-to-ogive?) that prevent simply loading to magazine length. In my Satern barrel, The SMK's COAL to just touch the rifling is 2.216, and the Hot-Cor is 2.160. Loading either of these to a straight 2.260 would lead to significant jamming into the rifling.

I believe this is represented in the load data that AA provides, as their recommended COAL for the 120g SMK is 2.220. Based on my own measurements, that isn't just a number they picked out of the air; there's a reason they included the COAL column rather than stating that all bullets could be loaded to magazine length. Since the other bullets you're using aren't listed, you need to gather that data from your rifle.

I would attribute the "sometimes works, sometimes not" aspect to variations in bullet ogive length (I think that's correct terminology). When measuring using bullet comparators, I've found variations of at least +/-.007 (ironically, most recently with Sierra 120g SMK's), which would change a load from jump to jam if the chosen seating depth doesn't have enough margin built-in.

I'm certainly not guaranteeing that you don't have something else going on; as mentioned, you may have a legitimate lack-of-throat issue. However, there isn't enough data to conclude that yet. If you make some OAL measurements and find that you're significantly shorter than expected, that would be an indicator; so would the recommended chamber cast. But since you need a OAL gauge/comparator anyway (IMHO), I'd start there.