6.5 Creedmoor load development: Reloder 17 and 140 gr. Sierra MatchKing (SMK) #1740

I’ve had great success with the 6.5 Creedmoor.  Normally I run the 123 or 142 gr Sierra MatchKing (SMK). My go to powders are Varget (for lighter loads) and H4350 (for heavies).  I decided to expand my personal knowledge base and start looking at some other powder and bullet combinations (the 142 SMK over H4350 works great, but variety is the spice of life).  This time let’s look at the Sierra 140 gr. SMK #1740 and Reloder 17 (note they don’t spell it Reloader 17).   The long range 6.5mm crowd is certainly familiar with the 142 SMK, #1742, but what’s up with its older brother the #1740.

You’ll note the 140 gr SMK (left) is shorter than the 142 gr SMK (right).  The 140 gr SMK has  banded G1 ballistic coefficients (BC) of .535 @ 2800 fps and above, and .526 between 2800 and 2000 fps, while the 142 SMK has BCs of.626 @ 2850 fps and above, .611 between 2400 and 2850 fps and .606 between 2050 and 2400 fps.  It seems like selecting the 142 gr over the 140 gr would be a no brainer, but there had to be a reason that Sierra offers both.  To answer this, I reached out to Sierra Bullets.

According to Sierra:

The #1740 140 MK bullet is often selected as a good choice for a long range bullet in those firearms that are barreled with slower twist barrels. For years the .260 Remington rifles made when it was first introduced came out with 1×9″ twist barrels. The 140 MK did very well in those rifles. The #1742 142 MK really needs a barrel twist rate of 1×8″for good stability.

The #1740 140 MK also had a more “standard” tangent ogive that can be a bit more forgiving when trying to determine an OAL for accuracy. Being very similar to the #1730 140 SBT GameKing, it was a very easy transition when switching from a target load to a hunting load in a dual-purpose rifle.

The #1742 142 MK of course has a considerably higher BC value than does the #1740. This in turn provides a noticeably flatter trajectory at extended ranges.

Both bullets have proven to be extremely accurate and continue to provide excellent results. There are valid reasons for each bullet.

The 140 gr SMK has the advantage of potentially be forgiving during the load development process and more compatible with slower twist 6.5 rifles.  My own experience mirrors this, finding it slightly easier to tune than the 142 gr SMK.

As far as the RL17, well, I’m giving it another try.  Some shooters report great velocity with it, but many anecdotal reports find it more temperature sensitive than other similar powders.  At this point in my shooting career I’ve burned up about 5 pounds of it and never had much luck.  Well it was sitting in my powder measure so why not give it another try?

Often my test guns for these load development posts are full house custom rigs that I built myself.  While this will often yield impressive results, the majority of shooters are loading factory rifles.  In the spirit of this, I used a factory Howa 1500 action that I put in a KRG 180-X-RAY chassis.

This is a pretty mean looking rifle.  I used the following parts from Brownells to put it together:

By simply ordering the parts and screwing them together, a rifle like this could be easily configured.  It shoots pretty well, below is a 5-shot group I fired at 100 yards with the 123 gr SMK.

Before we get to the 140 gr SMK and RL17, let’s take a few minutes to review the disclaimer.

WARNING: The loads shown are for informational purposes only.  They are only safe in the rifle shown and may not be safe in yours.  Consult appropriate load manuals prior to developing your own handloads.  Rifleshooter.com and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

I’m working with 4XF Hornady brass that has been neck sized in a Redding Competition die with a titanium nitride bushing.  CCI #200 primers have been seated in the cases with a CPS priming system and the powder has been measured to the nearest .1 grain.  Bullets are seated with a Redding Competition Seating Die.

Target distance was 100 yards.  All shooting was conducted prone, from a bipod with a rear bag.  All data was recorded with a MagnetoSpeed barrel mounted ballistic chronograph.

You’ll notice that the rifle didn’t like my starting charges, however, as the charge built, the groups improved significantly.

Is the 42.0 gr. .956″ (.913 MOA) group something to write home about, no.  However, it does offer sub MOA performance.  The 42.3 gr group has 3 shots through one ragged hole, with a fourth close by and the fifth a flyer.  I am not going to say I caused the flyer, because I didn’t.  But if that was caused by another factor such as a suspect case, we may be onto a load that could be worth another look.

This round of testing gave me a new found appreciation of the 140 SMK and reminded my why I’m not a huge fan of RL17.  Had we conducted this same test with the tried and true H4350, I’m sure the results would have been better.  In fact, that sounds like a great idea for an upcoming post!

Sierra has published it’s 6.5 Creedmoor data online.  To view it, click here.