Ive been reloading 123scenars for a couple years now....and I have always loaded em according to ojive measurement......but when u really measure the overall length there is a huge variance due to inconsistent bullet length. The meplat tip is different on every round....how do u determine what the correct length is?
Need help determining correct OAL
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I use the ogive measurement and determine the correct length by testing different lengths to see which shoots best in the rifle. I haven't found that it makes much difference in a SAAMI grendel chamber so I just use an OAL that's just short enough so that every round will feed through the magazine.
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Originally posted by rwh View PostI use the ogive measurement and determine the correct length by testing different lengths to see which shoots best in the rifle. I haven't found that it makes much difference in a SAAMI grendel chamber so I just use an OAL that's just short enough so that every round will feed through the magazine.
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2.265 is fine for the 123 Scenars. I wouldn't really worry about the OAL otherwise. In the Grendel it is really forgiving. I have a lot of reports of Sub .3 MOA using our ammo and we load to 2.265 COAL using the Base to tip measurement.
Mark Hostetter"Precision - The Pinnacle of Perfection."
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Originally posted by PrecisionFirearms View Post2.265 is fine for the 123 Scenars. I wouldn't really worry about the OAL otherwise. In the Grendel it is really forgiving. I have a lot of reports of Sub .3 MOA using our ammo and we load to 2.265 COAL using the Base to tip measurement.
Mark Hostetter
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Just built a rifle using a Shilen 20 inch barrel. I didn't know going in that there are several different chambers for 6.5 Grendel. Shilen does NOT use SAAMI spec on their chamber. I asked about it, and they sent me a drawing of their reamer. They use a shorter leade than the SAAMI spec. I loaded some 120 AMAX to mag length of 2.250,
and all went well for about 30 rounds, then I had a misfire. Tried to cycle the bolt, and it was stuck. When I finally got it open, the bullet stayed stuck in the throat. Needless to say, that stopped everything for that day. Got the bullet out and then used the hornady oal gauge to find out where I went wrong. The 120 AMAX uses an altogether different ogive than the 123 AMAX and MUST be seated short! 2.180 will do it. This was a stupid mistake on my part and could have resulted in a blown up rifle! Never assume that magazine length is fine for COAL when using a new bullet! I consider myself lucky that I don't have a face full of scrap AR15 receiver. From now on, every bullet change gets checked. No more guessing.
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Originally posted by Thomas View PostJust built a rifle using a Shilen 20 inch barrel. I didn't know going in that there are several different chambers for 6.5 Grendel. Shilen does NOT use SAAMI spec on their chamber. I asked about it, and they sent me a drawing of their reamer. They use a shorter leade than the SAAMI spec. I loaded some 120 AMAX to mag length of 2.250,
and all went well for about 30 rounds, then I had a misfire. Tried to cycle the bolt, and it was stuck. When I finally got it open, the bullet stayed stuck in the throat. Needless to say, that stopped everything for that day. Got the bullet out and then used the hornady oal gauge to find out where I went wrong. The 120 AMAX uses an altogether different ogive than the 123 AMAX and MUST be seated short! 2.180 will do it. This was a stupid mistake on my part and could have resulted in a blown up rifle! Never assume that magazine length is fine for COAL when using a new bullet! I consider myself lucky that I don't have a face full of scrap AR15 receiver. From now on, every bullet change gets checked. No more guessing.
It only takes a few minutes with the StoneyPoint and how often do we try new bullets? This is good advice.
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Originally posted by Thomas View PostJust built a rifle using a Shilen 20 inch barrel. I didn't know going in that there are several different chambers for 6.5 Grendel. Shilen does NOT use SAAMI spec on their chamber. I asked about it, and they sent me a drawing of their reamer. They use a shorter leade than the SAAMI spec. I loaded some 120 AMAX to mag length of 2.250,
and all went well for about 30 rounds, then I had a misfire. Tried to cycle the bolt, and it was stuck. When I finally got it open, the bullet stayed stuck in the throat. Needless to say, that stopped everything for that day. Got the bullet out and then used the hornady oal gauge to find out where I went wrong. The 120 AMAX uses an altogether different ogive than the 123 AMAX and MUST be seated short! 2.180 will do it. This was a stupid mistake on my part and could have resulted in a blown up rifle! Never assume that magazine length is fine for COAL when using a new bullet! I consider myself lucky that I don't have a face full of scrap AR15 receiver. From now on, every bullet change gets checked. No more guessing.
We learned that with the 120 AMAX when it first came out. However, we learned it by using dummy cartridges to find a length and not when shooting. Some guys had to seat that specific bullet so far into the case for it to chamber safely that the neck went past the shank of the bullet. Not a good design for the Grendel so few use it.
I never trust the OAL from any printed source. I always use a dummy cartridge to find the right seating depth. Most of the time with the Grendel it ends up what the printed material stated but not always.
LR55
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Well, they say experience is the best teacher. I did a lot of reading to find powders, etc., and never came across anything about 120 amax bullets, good, bad, or indifferent. Just figured if 123's worked, chances were that 120's would also, since the store didn't have any 123's. My only other choice was 140 grain Sierras,and they looked WAY too long. The hell of it is, the loads all shot really well. Every one sub MOA.
I wonder what they would do with a jump to the lands? Factory Hornady 123 amax match shot 1 1/4 inch at 300 yards, so I'm really pleased with this Shilen barrel.
Does anyone know the reason Lapua uses such small flash holes in their Grendel brass? Something to do with PPC case design, is it? Curious what the advantage might be.
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Thomas-
the hornady bullet comparator tool is your friend with the countless 6.5mm bullet choices we enjoy today!
before the 123 amax came out, I used the 120 amax in the grendel and had great results (SAAMI chamber, 2.185'' oal) I used BLC2 powder.
But the 123 amax has a better BC & better ogive profile to work in the grendel chamber, so most people don't use 120 amax in the grendel any more.
I believe Lapua was trying the small flash hole idea to send out a longer flame "jet" into the case for more consistent burn- I don't know if it actaully works or not
here is an article on it:
Conventional .308 Winchester brass has a large primer pocket with a large, 0.080-diameter flash hole. In 2010, Lapua began producing special edition .308 Win Palma brass that has a small primer pocket and a small flash hole, sized 1.5mm (.059) in diameter. Tests by U.S.
-hope this helps
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Thanks A.D.D. I now own a Hornady Comparator, should be a huge help. None of this was an issue with my .223/5.56 rifles, they all have enough leade that if you load to mag length there are no problems. I didn't expect any different with this rifle. Know better now. The longer flame jet makes sense, I guess. Must be common to the PPC family of cases?
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