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C.O.L. from manuals or from factory ammo?

2K views 20 replies 13 participants last post by  JRK57 
#1 ·
I started reloading about a month ago, and am looking for some advice. I'm loading 300 blackout using 110gr vmax bullets. The Hornady manuals state the C.O.L. should be 2.050". When I measured my factory Hornady ammo, it measured 2.090".

Which should I use?
 
#8 ·
A very good post, and video! Thanks!
 
#10 ·
re magazine length: On your ar bullet the die actually pushes on the secant portion of the bullet so your oal can vary as not all bullets are not equal. So build a round that takes that fudge factor in account so you don't have to waste time on the actual tip length vs magazine. Using the ogive for length measurement is more accurate than oal using the bullet tip but that takes one of the comparator varities to do and is time consuming. It's great for building the perfect round. Once you have that you can mass produce around a known good round. The most glaring example for illustration is lead tipped bullets. Some of those lead tips are rounded, bent, etc and you can see the oal variances easily across the room just looking at them.
 
#14 ·
Everyone, thanks for the great advice. Relaoder952, thanks for the video, it was very informative. I thinking have about 50 round loaded at 2.050, I may try some at 2.070 tot see if it makes a difference. Once I find out I'll let you know.

Thanks again
 
#15 ·
I normally recommend to new reloaders to find a "tried and true" load in your manual, preferably from the bullet manufacturer (Hornady bullets, Hornady manual. Sierra bullets, Sierra manual etc.), then buy components. Stick with the OAL as suggested and only work up powder charges. Seating depth is usually one of the last things varied for improving (?) accuracy and in my experience manufacturer's recommendations produce good to excellent results. Get the basics of reloading down (get to where you can produce ammo that is identical; powder charges, seating depth, crimps, etc, all the exact same) then experiment....
 
#16 ·
Unless you have the EXACT same bullet, a factory COL only tells you what worked for that bullet; however, for most rifles, COL is usually limited to what fits the magazine and COL is real easy—use the longest COL that fits the magazine without binding on the sides.
Your COL (Cartridge Overall Length) is determined by your barrel (chamber and throat dimensions) and your gun (feed ramp) and your magazine (COL that fits magazine and when the magazine lips release the round for feeding) and the PARTICULAR bullet you are using (line up a bunch of 55gn .224" bullets and you'll be amazed how the dimensions vary.
What worked in a pressure barrel or the lab's gun or in my gun has very little to do with what will work best in your gun. Thankfully, there is a range of COL that will feed for almost any bullet, letting you find the COL that works best.
Take the barrel out of the gun. Create two inert dummy rounds (no powder or primer) at max COL and remove enough case mouth flare for rounds to chamber (you can achieve this by using a sized case—expand-and-flare it, and remove the flare just until the case "plunks" in the barrel).
Drop the inert rounds in and decrease the COL until they chamber completely. This will be your "max" effective COL. I prefer to have the case head flush with the barrel hood (or a few mils higher than where the head of an empty case aligns with the barrel, as all cases are too short and I prefer to minimize head space). After this, place the inert rounds in the magazine and be sure they fit the magazine and feed and chamber.
You can also do this for any chambering problems you have. Remove the barrel and drop rounds in until you find one that won't chamber. Take that round and "paint" the bullet and case black with Magic Marker or other marker. Drop this round in the barrel and rotate it back-and-forth.
Remove and inspect the round:
1) Scratches on bullet--COL is too long
2) Scratches on edge of the case mouth--insufficient crimp
3) Scratches just below the case mouth--too much crimp, you're crushing the case
4) Scratches on case at base of bullet--bullet seated crooked due to insufficient case expansion (not case mouth flare) or improper seating stem fit
5) Scratches on case just above extractor groove--case bulge not removed during sizing. May need a bulge buster.
 
#17 ·
Just an FYI I'm using CFE BLK power which calls for a compressed load. I did the ladder test on different loads and settled on 23 gr. getting the bullets completely seated to 2.050 is tougher than a noncompressed load.

Thanks again for all the advice. This is a great place to learn from the more experienced loaders!
 
#18 ·
Just an FYI I'm using CFE BLK power which calls for a compressed load. I did the ladder test on different loads and settled on 23 gr. getting the bullets completely seated to 2.050 is tougher than a noncompressed load.

Thanks again for all the advice. This is a great place to learn from the more experienced loaders!
Have you fired enough of the CFE BLK to form an opinion on it? I've been using IMR 4227 for my blackout loads but I really like the CFE-223 for my .223 and .308 loads.
 
#21 ·
So I thought I'd follow up on an old thread I started back in July. After trying different COL's the shorter ones would cause a mis-feed or jam about every 3rd or 4th round, and it would damage the tip of the polymer bullet. (I have about 10 damaged bullets sitting on my bench). After I started seating the bullets to 2.090 or even 2.100 COL, the bullets feed correctly.

Also I like using 18.3 gr of H110 under 125 gr SST bullets. I shot 3 deer with this combination this fall. They work very well out to about 100-150 yards. After that they are not accurate or dependable.
 
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