I have a RRA varmint a4 with the 18 inch barrel and 1/8 twist. Doesnt look like the gun likes the 55 grain bullet. With this barrel do i need to go with a heavier or lighter round. I some 52 grain and it grouped great. I thought with the faster twist I should be shooting the heavier a bullet.
Faster twists will show better accuracy with longer bullets.
Longer bullets are usually heavier as well.
The difference between the 55gr and 52gr bullets you were using is probably in the QUALITY of the bullets.
The better the quality of the bullet, the better they are going to group as long as they are the appropriate length/weight for the twist rate of barrel you are using.
Your 1:8 barrel should be excellent with 77’s and 80’s, but your pocketbook probably prefers 55’s.
Doesnt look like the gun likes the 55 grain bullet.
I take it this is a problem with groups, and not reliability?
I’ve not encountered this in a 1-8 bbl (haven’t fired a 1-7 enough to have an opinion, yet). It’s even stranger that you found the 52gr a better performer in this twist rate, since it typically performs very well with heavier bullets. To be frank, I’m as confused by this as I imagine you are.
Was this problem with a single type/brand of ammo? 'Cause if so, I’d try another brand & see what happens.
Im asking this because I would like to start reloading. The 55 grain ammo i was shooting was partisan paruvian. Im sure the spelling is wrong but anyway, my bolt rifle loved it. My AR wont group well with it. Wonce I figure out this reloading concept I’ll have to try out a few different bullet grains .
link is not working.
I’ll post it again because you seem to have missed it…
Privi Partizan ammo is not going to have high quality bullets.
Get some black hills ammo with sierra matchkings.
Generally faster twists work best with longer bullets. BUT that’s not a concrete rule. A friend of mine has a 1x7 twist 20" barrel that shoots 52gr MATCH bullets more accurately than any other load tried in that gun (like 1/4MOA or smaller).
I have 2 LMT M4`s 14.5 barrels 1/7 twist
I shoot very tight groups with CHEAP White box WIN 45grHP
Winchester’s 45gr white box loads shoot great in almost every gun.
There’s something about that ammo that I wish they could figure out for all their other ammo.
If I had to pick an off-the-shelf ammo to use as an accuracy standard for testing of multiple rifles, I would use that 45gr ammo as it’s been consistently accurate for many many years.
I believe that Randall has given very good advice (as usual). Different barrels will have preferences for different bullets. In a given weight, you may find one brand/type that shoots crummy or well out of YOUR barrel. It requires experimentation. A really high-quality barrel may tend to be less finicky about bullets, but it will still group one better than another. Really high-quality bullets will be more consistently accurate in a wider variety of barrels. The only way to know what shoots to an acceptable level of accuracy is to test a particular bullet in a particular barrel. There are certainly other variables at play, but in my experience the bullet is the single greatest contributor.
I’ved also had good results with that ammo and my 1/7 barrels. I shot a few thousand of it back when ammo was a lot cheaper. I wish I still had that ammo…
I’ve said it before and I’ll repeat it again, with proper ammo selection the 1/7 can accurately shoot 45gr-77+gr bullets!
It is not uncommon for two different rifles to like two different types of ammo of the same caliber. What you are seeing is probably not due to twist but more likely due to chambering differences.
Randall also made a very good point regarding the inherent accuracy in mass market ammo replicating milsurp or current .mil loads or meant for cheap plinking. Garbage in = garbage out.
FYI, I’ve shot hundreds of rounds of match grade loads loaded with Hornady’s 52 grain Amax through a Rock River NM A2 with both 1/7 and 1/8 barrels with outstanding accuracy.
In Highpower circles, THE load to use for reduced course matches (200 yds or less) is about 25.5 grains of Winchester 748 and a Sierra or Hornady 52 on top loaded to mag length.
+1 Brutally accurate.
My 20" Heavy Armalite with the 1in8"twist was quite fond of the 69 grain Sierra Match HP, my load was 24 grains of Reloader 15, Fed Match primer, and a Federal case. All cases trimmed to min oal primer pockets cleaned and flash hole deburred Loaded to the max length posted in the sierra manual.