308 Q's, 178amax and 4064

[Fast14riot]

Was talking with my brother on the phone the other day, his R700 SPS in 308 (SAAMI chamber, factory barrel) is somewhat inconsistent. He says he shoots nice 1/2"-3/4" groups one day, then the next time it opens up to 1" maybe more. I don't know his specific load except that he is using Federal brass, IMR4064 and 178 AMAX bullets.

He will be starting a new load work up soon as he is switching over to Lapua brass. I asked to to send me pics of his targets when he does, but until then, what can cause these inconsistencies in his groups? His technique is pretty solid, has a good trigger and scope, bedded and pillars in his stock.

I don't shoot 308, so I'm not up on the finer details of the round or loads for it. He did say that he can seat the bullets out to 2.840" and still fit in the magazine. Are the AMAX jump sensitive? Potentially a good charge weight not in a node and temperature variations are causing it? He lives in AZ and I'm in CA, so I can't exactly sit down at the bench with his gun and see what's going on.

Just curious more than trying to actually diagnose without complete information, seeing if there are any major things that stand out.


-Alexander

 

[joshb]

Could be something as simple as too much coffee. Might be a little wind or mirage, too. Going between 1/2 to 1 inch groups with a factory gun is doin pretty good. Might suggest he try some Sierra BTHP. I got great results with them. Then I found a good deal on some Hornadys and bought 3 k of them. My gun liked the Sierras more. Now, I gotta shoot em cause I bought em. I jump and jamb both with only minor changes in group size. ( These are factory Remmy 5rs, not customs) I'm also using various brands of brass. Federal and LC mostly. Have not sprung for any Lapua yet as I have about 4K of other brands and I'm shooting more 6br and 223 these days.

 

[Fast14riot]

He's tried SMK, Varget, and other combinations too. I will see what his ladder looks like when he shoots it. Maybe his brass is really inconsistent.

-X

 

[mac86951]

Temperature could be it. Keep ammo out of sun?

 

[johnfred1965]

IMR4064 is a good powder for 308, but it is a bit temp sensitive. I'm with joshb though, with a factory rifle, your friend is probably shooting within the accuracy window of the gun

 

[SmokinJoe]

I have found that my factory 308's are somewhat sensitive to how they are held in the rest, so he needs to investigate that maybe, and be sure he uses the best technique every time. If no wind flags are being used, they would help improve consistency also. Hope this helps.

 

[danny]

I hate to say this, but I can accuse myself of this issue as well, so understand it from that perspective. Maybe the rifle and load are fine, and like me, he sometimes has a "wandering zero". I know that I can't always " keep it together", especially when bench shooting, and the target suffers.

Danny

Could be something as simple as too much coffee. Might be a little wind or mirage, too. Going between 1/2 to 1 inch groups with a factory gun is doin pretty good. Might suggest he try some Sierra BTHP. I got great results with them. Then I found a good deal on some Hornadys and bought 3 k of them. My gun liked the Sierras more. Now, I gotta shoot em cause I bought em. I jump and jamb both with only minor changes in group size. ( These are factory Remmy 5rs, not customs) I'm also using various brands of brass. Federal and LC mostly. Have not sprung for any Lapua yet as I have about 4K of other brands and I'm shooting more 6br and 223 these days.

 

[Fast14riot]

I hate to say this, but I can accuse myself of this issue as well, so understand it from that perspective. Maybe the rifle and load are fine, and like me, he sometimes has a "wandering zero". I know that I can't always " keep it together", especially when bench shooting, and the target suffers.

Danny

I'm inclined to agree to this (even for myself, I've thrown a match or two away for similar reasons). My brother is very impatient and known for changing more than one thing at a time. He lives in AZ, so his load is built around the temps there. I know he did get a new scope and trigger at the same time, but for the most part his groupings have been consistently going up and down in size.

Also, according to him, I don't know a damn thing because I don't shoot steel in the desert like he does, but I remind him that I got the common sense to not go to the desert in AZ, lol! But, he did ask me for help this time, so once I get more details and group pics from him I'll come back with my report.

Thanks for the thinking points.

-Alexander