More Chrony reports!! ((WARNING!)) lots of pics.

[Bwild97]

Gunner, In light of your question on col, I had to revisit Rasp65s' method of measurement. Recent events have had me questioning whether or not I was getting a true measurement to the lands; so I modified and revised the method to to satisfy my cuirosity.

My method (The short of it) : with a sized case, seat a bullet so that the boattail is below the neck, lock bolt back, chamber the case by hand, release bolt, remove case and measure. I performed the procedure 5 times, and got exact same measurements every time.

With a 120g SMK, the COL to the lands for (my barrel) is 2.312" and for the 130g NORMA Gold Target "LTL" is 2.398"



I would be glad to give more detail and pics if any one is interested in trying this for them selves!!

[RangerRick]

With the 31.5 grain CFE lad I noticed you loaded to 2.31 COL. Was that to avoid a compressed load? Can you load the 130 grain bullets mag length?

Those are awesome velocities for a 130 grain bullet in a Grendel!

RR

[Bwild97]

Rick, I had to load that long to keep the powder compression from deforming the ogive of the bullet, yes they can be loaded to mag length but at a max charge of 29.5gn of CFE223

[txgunner00]

Hmmm. Interesting. Does your rifle have a true Grendel chamber? I always thought the 120s couldn't be seated to mag length.


I'm now considering trying the 120s. I backed off the 123s mainly because of cost and switched to Hornadys. The Hornadys are doing well but I like to have multiple options and data collected for them in case there is a shortage of one component or another.

[terrywick4]

With a 120g SMK, the COL to the lands for (my barrel) is 2.312" and for the 130g NORMA Gold Target "LTL" is 2.398"

I notices your COL for them is 2.250, have you tried longer? .062 (2.312-2.250) isn't a big jump but I seem to get better results with a .02 - .03 jump to lands (when possible). . . BUT you are getting pretty good groups now

[RangerRick]

Hmmm. Interesting. Does your rifle have a true Grendel chamber? I always thought the 120s couldn't be seated to mag length.


I'm now considering trying the 120s. I backed off the 123s mainly because of cost and switched to Hornadys. The Hornadys are doing well but I like to have multiple options and data collected for them in case there is a shortage of one component or another.

I've fired hundreds of SMK 120's with 30.4 grains of AA 2520 in a Satern Grendel barrel. Alexander Arms lists the COL as 2.22, but I've loaded to 2.26 with no problem.

RR

[Bwild97]

Does your rifle have a true Grendel chamber?

Yes it is a SAAMI chamber, but I'm thinking that the throat is just a tad tight. When I chamber a 120g load or any load other than the 130g seated to 2.265, I am unable to easily remove it from the chamber, and thinking that it was stuck in the lands. But after removing the projectile from the chamber, I noticed the absence of land marks on the projectile; This had me wondering WTH is going on. So I resorted to the "brute force" method of getting COL to the lands. Now I am wondering... is this an anomaly in my barrel or is this normal?

[CTone03]

Yes it is a SAAMI chamber, but I'm thinking that the throat is just a tad tight. When I chamber a 120g load or any load other than the 130g seated to 2.265, I am unable to easily remove it from the chamber, and thinking that it was stuck in the lands. But after removing the projectile from the chamber, I noticed the absence of land marks on the projectile; This had me wondering WTH is going on. So I resorted to the "brute force" method of getting COL to the lands. Now I am wondering... is this an anomaly in my barrel or is this normal?

Same thing happens to me with a LBC chamber. My gun loves the 123 Amax/XBR/2.265" combo that's a proven performer, but the rounds seem to stick in the chamber. Sometimes I have to pry the bolt back to get them out, and the bullet shows it's not hitting the lands. I've measured to the lands with that bullet using a comparator, and if I recall there's a good ways to go before I get there. Last night I chambered a few loads I just did in new AA brass, and there were no stuck cartridges or land marks on the bullets, which leads me to believe it's as you said: a tight throat. It seems to happen with fired and reloaded brass, and not as much with new brass.

[JASmith]

Can you see any evidence of rubbing on the neck or case body? Or evidence of rubbing on the bullet not attributable to engraving on the lands?

Some bullets are a tad more stiff than others, so the outside diameter of the neck might be a bit larger than normal. One might be able to measure the neck O. D. for both the ones that work OK and the ones that stick. That might also help tell whether it is the chamber neck.

[Drifter]

Regarding cartridges that are tight and sticking in the chamber, color a dummy round (case and bullet without primer and powder) using a black Sharpie pen, then chamber it. There should be tell-tale marks showing which part of the cartridge is encountering the tight fit. (Some markings will be normal.)