Wondering about 170 Lapua lock base FMJ

[Brutus]

I decided recently to experiment with differing match bullets for two different rifles: Remington 700 Varmint in .308 topped with good optics & a Wichita 1375 actioned TR also in .308. Now I believe I've arrived at a good recipe for the Wichita using 155 Scenars & Varget. No problems here at all.
I wanted to try 170 lock base in the Remington with the same powder.
As of today I'm getting the odd flyer (1 out of 5 shots) with the 170s out of the Remington.
I was wondering if anyone has had similar issues with these Lapua 170s out of thier stock Remington rifles?(1:10)
Starting to feel the Remington should be rebarrelled with a custom pipe. As of now, my Wichita (Krieger 1:13) using iron peep sights & Scenars, outshoots the Remington @300 meters & hovering around one inch better.
Perhaps I just have not found the right handload formula yet?

Edit: Current situation: Remington 700, 1 MOA: using good optics, factory barrel & selected handload.
Wichita 1375, very close to 1/2 MOA: custom barrel, good peeps & easily found handload.

 

[Brutus]

Going to experiment with different handloads using the 170 Lapua LB bullet, some with Varget & some with R15.

 

[rnbra-shooter]

Factory barrel on your Rem? Remington 700s have pretty long throats. It's quite likely that your 170 lockbase has a really long jump to the lands. Sometimes this doesn't matter much or at all, other times it can prevent you from getting good results. You can try loading the bullet hotter, or a bit longer; you might or might not be able to solve the problem.

Since you own a target rifle with a good barrel, you know how well a good rifle can shoot (and, how easily and consistently, across a wide variety of ammo combinations). You're probably spoiled, and you'll have to get a match barrel for your Remington too ;-)

FWIW I helped a friend set up a factory Rem 700 VS a number of years ago. We ended up using Sierra 190 matchkings, which are a long enough bullet that we could touch the lands. The ammo was comically long (3.1" IIRC?), and wouldn't even come close to fitting in the magazine, but as precision ammo for 400-600-800 yards it worked really, really well.

 

[Brutus]

Thanks for the splendid advice Rnba. It's nice to know I'm on the right track because as of now the handloads for the Remington are 2.888 OAL. Yes, single loaded.
And you are also absolutely correct about the custom barrel on a factory rifle. The longest the 700 will still wear the factory pipe is 18 months or so. I'm thinking a Krieger but I'm open to other suggestions from very well informed persons such as yourself.

Cheers!

Edit: Yes Rnba, currently a factory barrel on the Remington.