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Question about 175 grain bullets.

5K views 14 replies 12 participants last post by  Long Ranger 
#1 ·
I am thinking about buying some 175 grain SMK's to shoot through my m1a. It is a SA loaded with cluster rail, and it is holding around 1 moa, and sometimes better, with Ultramax remanufactured ammo (Speer 168 grain BTHP reloaded into used LC brass) from Cabelas.

My barrel is a SA national match stainless with a 1 in 11 twist. Will this be fine for 175 grain bullets? Also, will my gas system be able to handle them?

Another thing I am wondering about is replacement drop compensator turrets for Leupold scopes. I'd like to get something for 147 grain and 175 grain bullets. The scope came with a 168 grain turret.
 
#2 ·
There is a rather large discussion that has gone on and is currently on going about he 175 vs 168 in the M1A. The 175 is a great bullet as is the 168 for the M1A. The standard twist for the M14 was 1 in 12. I can tell you that in a 1 in 11 twist both the 175 and 168 bullets shoot just fine depending on loads. I have two 1 in 11 inch twist bolt guns and I have spent a lot of time with a 1 in 11 heavy barreled M1A and they both shot the 168's and now the 175's very well.

As far as cam turrets for the Leupold M3's, there will be some difference in the two. Leupold doesn't at this time offer a stock turret for 175. Only the 7.62 168 grn, one for 5.56, one for 30-06 and one for 300 win mag. My M3's came with all 4. However, If you provide the ballistic information to Leupold they will make you a specific cam for your needs for a price. I've never tried it so I don't know what it costs. You would need to consult customer service by phone to get an idea and Leupold has a 1-800 number just for that purpose. It may involve you having some sort of information concerning the ballistics of your round which may require that you chronograph your gun to get it right. Good luck.
 
#3 ·
M1A's love 175gr SMK bullets. The 1:11 twist barrel will handle them just fine. Powders like IMR4895 and Varget are well established as powders for this bullet. I use 175 SMK/41.0gr IMR4895/LC04 case/CCI 34 primer. Absolute tack driver load out to 600 yards.

These bullets buck the wind better than any other I have tried. Same load I use for 168 SMK. As far as bullet drop is concerned, the 168 and 175gr SMK are very similar. The difference is in ballistic coefficients and ability to resist windage drift. I suppose you could use the 168gr turret for the 175gr SMK as well. Only 7 grain difference and it is all about velocity and gravity and velocities are similar due to load compression of larger 175gr bullet. Hope this helps some.
 
#5 ·
Don't have the link but if you go to Leupold's site and look under the custom shop, you will find not only prices but order forms that you can download. You might even find that they have one already for the 175 smk if your velocity matches a standard factory load.
 
#6 ·
I checked out the Leupold custom shop site. A new dial is $99.95 and you do need to know several things about the load including velocity. However, you might be able to have one made for the GMM .308 rd loaded with the 175smk and be right about on.
 
#8 · (Edited)
Only speaking about this .30 cal platform in M1A.

Not that I've had much personal experiance w/ different twist barrels. I can't even remember what I chose when I built my two match rifles. 1:10 or 1:11, I don't loose sleep over it. So, FWIW..........

Generally the "match shooter" will choose the faster twist (1:10 or 1:11) to stabilize their heavier bullets (168 gr.). Now a days with the 175 gr........well "maybe" a 1:10 will get picked over the 1:11. Also, I often note, that the big name barrel makers have them in 1:10 for match shooters.........does that mean anything? Try doing a search for an M1A barrel at Fulton Armory or Champion's Choice or your favorite site.

The old 1:12 twist was used by Uncle Sam (M14) for the standard weight bullets (147 gr./150 gr.) as that is what the regular grunt would be using. Note that replacement standard weight barrels for the M1A are generally made in this twist. Does that mean anything?

Anyway, for some.......the 1:11 is a "compromise." Being that it falls between the 1:10 and 1:12. They might be thinking that they can use it to shoot reg. bullets or the heavier match bullets. Yes, it works.

And, the M1 Garand used a 1:10.........so???

Like most everything..........your mileage will vary.

Aloha, Mark
 
#9 · (Edited)
There's another company that will make good custom ones. Unfortunately the name escape me and I can't find the link. If I do, I'll post it later.

Keaton? Kenton?

Sorry!


****************** FOUND IT *******************
http://kentonindustries.com/

Also make target knobs for scopes.
 
#15 ·
Good to know

My first match barrel was a 1:10", the second was a 1:12". My third will be a 1:12". It does MUCH better with bullets 155 and less and does great up to 178grs.

Ty
Thanks 30Cal, for that information. I have a Mike Rock 1/12" on the way, and was wondering if the twist might be too slow for the match 173 grain bullet. Sounds perfect.

ARMY1
 
#11 ·
The 1 in 10" twist was the original rate for the 30-06. It will stabilize up to a 220-240 gr bullet, at rifle velocities. The 1 in 12" twist was standard for the .308 due to the fact that anything over 190 gr is very seldom used. Most factory bolt guns in .308 are 1 in 10", however. I would say that is so they can use the same barrel blanks for both calibers.
 
#12 ·
A 1-11 or 1-12 will be fine. The length of the bullet is what determines the twist. A Sierra 168 and a 175 are only a few thousanths diffrent. If I were shooting at 1000 yds. I would err to the faster twist. Out to 600 a 10,11,or 12 will do fine.HTH. Also give IMR 4064 a go for the 175s. Its a long grain powder that does not meter well through most powder measures, but it is a good place to start.

John
 
#13 ·
I want to second the IMR 4064 thoughts. It has a bad rep but in my experience it has been a stellar performer out of my M14's When I use metered and not weighed charges.

Esp when I started using the 175gr. bullets I turned in some incredible groups with it...I have completely quit using off the self Ammo and only shoot my 175 gr. handloads in all my m14 type rifles as well as my FAL.

Living in the Desert, I often shoot out to 1000 meters or more and can tell you I am the weak link in the equation.

Hans
 
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