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Old March 3, 2013, 09:44 PM   #1
brokenanew
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Experience shooting 175gr .308 out of 1:12 twist??

Well. My Remmy 700 .308 VTR (20" of groove barrel) is a great shooter. Consistent sub MOA and often hits at and below the half inch mark even with 4 shot groups (best 4 shot group is .284"). Overall it averages around .6" for 4 shots with 168 SMK behind 42 gr of RL15.

However, Im thinking I might get bold and try to acquire a 1000yrd shot.
I know I'm going to need at least a 175gr. Ill be using RL17 for better velocity.

My question is have you shot 175 gr out of a 1:12 twist barrel? What was your experience? I have spoke to one individual who claims some rifles will do it, some wont. I don't want to drop money on the bullets and powder if there's really no chance in making it work.

Whats ur experience?
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Old March 3, 2013, 09:57 PM   #2
WWWJD
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I think it's totally doable. See the 10 shot group below:



I only ever bought the one box of bullets; need to try some more. Maybe this summer. I tweaking on some 168gr Berger VLD Hybrids at the moment. Rifle is a 20" 1:12 Remington SPS .308.
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Old March 4, 2013, 10:27 PM   #3
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I'm trying to figure why you want to go with R-17 over R-15.

You can get all the velocity you need out of R-15, which by the way works better in the shorter 20 inch barrel.

Velocity isn't accuracy. I wouldn't go over 2600 in a 308, not need too. 175 at 2600 MV is more then enough for 1000 yards.

But that's just me.
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Old March 4, 2013, 10:35 PM   #4
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+1 what Kraigwy said! I load mine down to 2570 fps (21.75" 5R barrel) and they do very well @ 1K. In general, I slow all my .308's down a bit and seem to get less 'flyers' per group. If you need more speed or heavier bullets at that range get a 300 win mag.
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Old March 5, 2013, 07:40 AM   #5
stubbicatt
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Yep. 43.3 grains RL15 and 175 gr. SMK. Excellent accuracy and very mild recoil.
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Old March 5, 2013, 12:06 PM   #6
brokenanew
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To get 175 gr to hit the 2600 MV dont you have to run close to max?
I usually use rx15 but Im hearing some great things about rx17 for thoe bullets above 168 gr. Keeping accuracy and boosting velocity. Ive been wanting to try if for accuracy anyways
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Old March 5, 2013, 12:51 PM   #7
Bart B.
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1:12 twists have been used with great success for the .308 in competition. Both the military's M14 and M1 rifles chambered for it had standard barrel twists at 1:12. Bullets from 150 to 180 grains won matches and set records from both. Only the M1 and its 24 inch barrel did well with 190's; the 22 inch tube in M14's wasn't quite long enough to get enough muzzle velocity to spin 190's fast enough to keep 'em stable to 1000 yards.

In warmer weather, i.e. above 70 deg. F, a muzzle velocity of 2500 fps will stabilize a Sierra 175 HPMK well enough from a 1:12 twist barrel in elevations above 2000 feet. Cooler weather and/or lower elevations will need a 1:11 twist at that exit velocity. The arsenal loaded 175 HPMK's leave 22 inch barrels at about 2600 fps; about 2550 fps at 26 yards where the arsenal chronograph measures their speed.

Note that the 7.62 NATO and .308 Win. rounds were both developed with 1:12 twist barrels and that's what Springfield Armory (in MA) and Winchester barrels had. Bullets from 150 to 200 grains were tested with that twist and all did great; the 200-gr. ones by Winchester were good enough for hunting use up to 200 yards which is what they were meant for to begin with.

For what it's worth, I don't think any powder will produce the accuracy for 175's in a .308 case that IMR4064 will. That case with that powder's shot test groups with 168 through 190 grain bullets smaller than or equal to current benchrest records. But you gotta weigh each charge; it don't meter too accurate.

Yes, it takes max loads to push a 175 out of a 24" barrel at 2600 fps. More than max to get that out of a shorter barrel unless one uses one of the super powders now on the market. But how accurate will one of those super powders shoot them?
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Old March 5, 2013, 01:12 PM   #8
5R milspec
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The info you have been reading is linked to 200gn or higher bullets with R17.If I am not wrong it all got started with a gent over at snipershide,and he has a 1:12 twist 20 inched barrel.I'll have to say that its nice to see a 308 do something a 300wm was born to do,I even tried it but walked away fast.

Now As Bart B. has already said,your barrel and choice of bullet will work just fine.The powder you already have will do just fine.If wanting to load from the mag take your time looking for that one load for your rifle.If you want to hand feed then go for it.Will have to say I too have been loading and looking for a load for a Remington SPS with a 20" barrel.I went with 4064 and found it hard to get enough powder into the case with mag feedable ammo.I soon had to throw away the idea of mag feeding,so now we hand feed for it.

I think your choice of powder ( R15 ) will be better for you when working up,for its a smaller sized stick shaped powder,but their again I like 4064 when I cannot find Varget.Just start with a mid range load and work up to a book max,maybe a little over book max looking for pressure.When you see to much pressure then stop,I think you will soon find out to how well your rifle will shoot a 175gn match bullet.
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Old March 5, 2013, 05:03 PM   #9
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Bart B is the go to guy, can't go wrong IMO. Keep up the good Info. Chris
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Old March 7, 2013, 10:52 PM   #10
brokenanew
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Good info! Thanks. Ill pick up a box tomorrow and load some up for the weekend. Ill probably have to stick with Rx15 as i cant find any rx17 anywhere anyways and I have a few pounds of rx15 left.
Loads will be loaded at mag length, truth is Ive played a bit with the seating depth and seems to like mag length which is almost an full 1/10th an inch of jump...weird. But when I played with seating depth I didnt adjust charge bc...I didnt know how to adjust per seating depth.

Besides Im shooting respectable subMOA (4 shots) and some sub1/2MOA groups with the current load. Even with my hunting load using SSTs I average ~ .7" groups. I'm happy with that. Stock everything, even the stock is the cheap synthetic but I did have it bedded with the barrel floated.

I'm honestly going to shoot much til this dry spell of supply ends
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Old March 8, 2013, 04:25 PM   #11
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for you Bart Bobbit fans... check this page. some great info here, for sure...

http://yarchive.net/gun/index.html
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Old March 14, 2013, 02:03 PM   #12
brokenanew
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Well I picked some (175gr SMK) up and I went ahead and got a lb of rx17 for kicks. Im going to try the rx17 and compare it to the rx15. (shrug) why not?

Ill let you guys know how it turns out.
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Old March 14, 2013, 04:30 PM   #13
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http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
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