Hello, everyone!
I recently discovered that the COAL "jam" lenth for the Hornady 178gr BTHP Match bullets I'm loading up for my .308 Model 11 Hog Hunter is 2.920 inches. That is quite a bit longer that the SAAMI spec of 2.80 inches, resulting in a "jump" of 120/1000 inch. I've purchased a PTG DBM bottom metal (which looks totally solid!) that I've been hoping to install with a future precision stock, but the COAL in the AICS PMAG I have is still limited to 2.86 inches, still leaving what I believe to be quite a bit of jump (60/1000 inch).
My understanding is that a jump of anywhere from 10-20/1000 inch is ideal for accuracy, so I would like to stay as close to that as possible.
I've picked up a box of FGGM 175gr SMKs (2.80 inch COAL) to try out the next time I make it out to the range, and will compare their accuracy to that of my 2.90 inch COAL handloads. I expect that my handloads, with just 20/1000 inch of jump, will be more accurate.
If I choose to move forward with my DBM Bottom Metal and Precision Stock Project, how much of a pain in the butt (wallet!) might it be to have a smith re-chamber my existing barrel for a 20/1000 inch jump at my 2.86 COAL load? (And if you can recommend a reputable smith in the Tacoma, WA area, I'd really appreciate it so that I can go talk with him directly!)
Or, am I making a big deal of nothing, and my 2.86 inch handloads should do just fine with a 60/1000 inch jump??
Thank you all in advance!
Acdieter
This is JMHO. With all the Savage buyers with 308's that are getting stuck with throats so short they can't chamber factory loads, "you should feel blessed"! Chasing the lands is way overrated. Even Berger, who was the king of "jamming the lands", has now decided their pills could work out to .140" otl's. If you don't want that barrel, PM me ! :-)
FW Conch meant to say PM me first, then him
They have long had..long throats. Nothing like what is found in Weatherby rifles, but long anyway.
As said, don't worry about it. It's becoming vogue to ensure someone doesn't stuff a bullet, and since it also seems popular to over-load the snot out of things; add a long throat and bleed some pressure off first.
I'm a firm believer in the theory that if it bleeds, I can kill it.
Think of the powder you could stuff in that thing loaded out to 2.930. Where is Mr eye?
The Dunning-Kruger effect is alive and well.
Oh yes, I have been seriously excited over the possibility of a larger boiler room..., but, according to Quickload, there really isn't too much performance difference between COALs of 2.86 and 2.90 inches. About 0.6 grains and less than 40 fps.
In preparation for my next range trip, I loaded up a batch of 178gr BTHP Match at 2.90" COALin for a round of Dan Newberry's OCW testing. I'd really like to use the PTG DBM bottom metal later, but accuracy is more important than convenience, so I'm going to load up another batch with identical components, but at my magazine length limit of 2.86" to see if there really is anything to be gained by being right up there on the lands. I suspect that it is more important to have uniform brass dimension and concentricity, powder charge, and CBTO length.
Speaking of uniform CBTO length (or suprising lack thereof, actually), I took my Hornady Comparator to a box of brand new, off the shelf, FGMM 175gr SMK to see how they compared. I was shocked... They were all over the road, anywhere from 2.208" on the low end to 2.221" high end- a range of 13/1000 inch! By comparison, using the less expensive Hornady 178gr BTHP Match bullets and seating them with my Forster Ultra Micrometer seating die, my total variance for the 25 rounds I loaded for the 2.90" COAL OCW test batch was only 2/1000! I don't have a concentricity gauge yet, but after seeing that range of 13/1000" CBTO with the FGMM, I'm really curious to see how their run-out compares to my neck-turned Lake City brass. Once I get my Lee Collet neck-sizing die in, and process my fired brass with that, I feel pretty confident that my brass will be even more concentric than the FGMM.
'Sorry to run on about this. I guess I'm just hoping that concentricity and uniformity is more important to accuracy than keeping the bullet close to the lands.
Thanks for the offers, FW Conch and Darkker, but I have a pretty good feeling this barrel is going to work well for me. ;-) I really appreciate the your offers and experience!
I'll post an update after my range trip regarding how the FGMM and my handloads at 2.90" and 2.86" all compared.
Acdieter
Last edited by acdieter; 01-14-2016 at 11:10 AM.
Berger has a 308 185gr classic hunter. The shape should allow less jump at your possible col. Has a slight sacrifice of BC on those bullets. I will reference my berger book when i get home. They have a quick reference in the book with tail, bearing, and nose lengths. I will compare against a there vld of similar weight.
I've had pretty good luck with Hornady bullets in the past, and I have a pretty good stock of these 178gr BTHP Match. That, combined with their excellent BC and significantly lower cost than Berger or Sierra, is reason enough for me to stick with them. I appreciate the input, though, Adammiddagh.
If money were no object, I would seriously be all over those 185 gr Berger Juggarnauts!
Acdieter
What I have suspected for a while, but of course no one will say, is whether or not that is really a SMK.Originally Posted by acdieter
The reason I question is because it's Federal, which was rolled under the ATK flag; who operates the Lake City arsenal. The SMK is a "Gub ment" approved bullet, meaning that EVERY defense contractor gets to make them. Thus Lake City also has the "175gr SMK", just not build by Sierra with the same machines. You can find them for sale from various sources, such as RMR. They shoot well enough, but "real" SMK's.
I'm a firm believer in the theory that if it bleeds, I can kill it.
It sure would be fraudulant and deceptive for Federal to put the "Sierra" logo on their box and lead the consumer to believe it is the Sierra Match King bullet, if the bullet in the box isn't actually manufactured by Sierra. Being in the service myself, I have seen and been dumbfounded by the way government procurement "works." (I use the term "works" very loosely!)
If you want to pay a little more money for a little more OAL the AICS mags go out to 2.9 and they say to load 2.880 to leave .02 clearance.
http://www.midwayusa.com/product/2898468203/accuracy-international-magazine-accuracy-international-chassis-system-aics-short-action-308-winchester-steel-matte
Thanks for the tip, doodedg. At nearly twice...well, half again, anyway, the price of the AICS PMAG, I'm going to give the PMAG-loaded-length a shot first before spending the extra money on another magazine.
Speaking of other magazines, I'm just now remembering that the Alpha Type-2 magazines were rumored to have a longer allowable COAL, but I'm not sure how much longer. Anyone have any experience with them?
I just checked the Alpha magazine website (http://www.alphaindmfg.com/store/ind...&product_id=51), where they list the maximum internal length of 2.965 inches. At roughly $70 each, they're $30 more expensive than the Magpul... If my grouping is significantly better closer to the lands, I may bite the bullet and go for one of the Alpha Type-2s after all. (This sure would be a much less expensive solution than addressing the matter via a change at the barrel level!)
Last edited by acdieter; 01-15-2016 at 03:25 PM.
I agree is seems shady, but all about marketing. The past many number of years Federal has been selling their ammo, say hunting ammo for the 308. With "Federal" premium bullets. Only again due to the ATK banner, those bullets were Speer built bullets(WAS also part of ATK). So depending upon how you want to view the world, those could be:
A - Federal premium bullets, built under production from Speer.
B - Speer bullets with the wrong name.
Again this is merely talking out loud, are they "Sierra" SMK's, or are they Sierra's that they purchased? Interesting to think about anyway.
I'm a firm believer in the theory that if it bleeds, I can kill it.
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