77gr SMK load

paxfish · Nov 19, 2018

After a bunch of testing, we too settled on 24.0 Varget behind 77gr SMK. Nice tiny groups.

The primer brand did not change our results, and we use both CCI and Wolf SRP in a 20 inch HBAR service rifle.

We trickle charge and I give the loading tray about 10 seconds of tapping to settle the powder before seating. Using consistently trimmed 5.56 cases, sorted by brand, compression does not seem to occur...

Jerry M · Nov 20, 2018

24.0 grains of Varget with a 77 gr OTM is also the standard load for the MD State Rifle Team for Infantry Trophy Team (Rattle Battle) matches.

KRC · Nov 20, 2018

Thanks for posting your results. I have the 69 grn. SMK's shooting very well, and just invested in 500 77 grn. SMK's, so have been watching this thread. My goal is load development to produce excellent 100 yard precision, then shooting from 400 to 600 yards with better wind resistance than the SMK 69's.

No clear winner, or even acceptable precision yet for me from Varget, H4895 or RE15. I am unable to get 24.0 grn. Varget into a case without serious powder compression and bullet spring back (at 23.7 grn.). I have multiple confounding issues including a tight chamber requiring resizing with a small base die, use of Lapua cases which are thicker than most (now trying LC cases), moly coated bullets, and I use relatively light neck tension as I've found both my RRA Varmints are very sensitive to this parameter. I just modified a magazine to allow a longer OAL, so this may assist. Is anyone loading with OAL's longer than 2.260" with a modified mag? Or loading the 77's with a tight/SB chamber?

steves1911 · Nov 20, 2018

I would try a diffrent bullet your rock rivers may just not like the smk. 24gr of rl15 with a 77 or 75gr bullet is an incredibly popular load . I use it with the 75gr hornady and have run it through 7 diffrent rifles and they all shot it quite well. Two of my rifles have tight chambers but not so bad as to need a small base die.How do those guns shoot with other loads? How are you adjusting your neck tension? Are you crimping the bullet?

KRC · Nov 20, 2018

I am just at the beginning of finding a 77 gr. SMK load, way too early to be giving up on any bullet or powder. But 24.0 grn. will NOT fit in the case with an OAL of 2.265 (my unmodified mags work with this). I am only working up the one rifle now, and it shoots 55 grn. SBK's and 69 grn. SMK's VERY well. This rifle has a tight chamber which absolutely requires use of a SB die (another story as I did not know this at first - the other RRA Varmint does not have a tight chamber). Neck tension is adjusted in .001" increments with a neck bushing die and individual bushings. NO CRIMP EVER!

steves1911 · Nov 20, 2018

Have you tried running a long drop tube to fill the case? When i use max loads of varget i always use a 12 inch drop tube and then tap the tray several times before i seat the bullet. If i dont i have problems with oal consistency. Varget can be a pain in the ass in cases with small volume because of its long kernels. I have found that my most accurate loads with it in 223 and 308 are all slightly compressed.

KRC · Nov 21, 2018

Pre-weighed powder charges sprinkled from a glass vial through a 12" drop tube. Even tried vibrating the cases.

paxfish · Nov 22, 2018

KRC - I use any 5.56 case, sorted by brand, but have no lapua. Trickle charged and tapped.

OAL under 2.26.

KRC · Nov 22, 2018

Do you have fairly tight necks? (Do you know the diameter of your neck sizer?)
What precision are you getting at 100 yards?

dist1646 · Nov 22, 2018

KRC said:
I am just at the beginning of finding a 77 gr. SMK load, way too early to be giving up on any bullet or powder. But 24.0 grn. will NOT fit in the case with an OAL of 2.265 (my unmodified mags work with this). I am only working up the one rifle now, and it shoots 55 grn. SBK's and 69 grn. SMK's VERY well. This rifle has a tight chamber which absolutely requires use of a SB die (another story as I did not know this at first - the other RRA Varmint does not have a tight chamber). Neck tension is adjusted in .001" increments with a neck bushing die and individual bushings. NO CRIMP EVER!

Have you checked your scale to be sure it is accurate? 24 gr. Varget w/ 77's does crunch slightly in my brass but, nothing to be concerned about. 23.5 gr Varget has worked well for me also, in case you are not comfortable with 24 gr.

I tested several loads and powders using multiple rifles to find what would be the most accurate and there was not a great deal of difference between the most popular powders used for across the course at that time. The best load in terms of overall accuracy, using a half dozen rifles and 10 shot groups fired at 200yds., was 23.5 gr. N140 using the Sierra 77gr matchking. All of the rifles tested had chambers set up for using 80gr bullets single loaded.

Remember, every rifle is different and will have it's own preference for loads, even though some may be extremely close. Don't worry too much about obtaining max velocity. Instead, focus on group size. The difference downrange is made by being able to read the wind and being consistent in the way each shot is executed.

Cutty · Nov 22, 2018

26.5 CFE223 is my go too load with 77 smk. It's extremely hot and I can't shoot it over 70 degrees but it's one hole at 3050 fps. I tried ten other powders and no luck.

dist1646 · Nov 22, 2018

Cutty said:
26.5 CFE223 is my go too load with 77 smk. It's extremely hot and I can't shoot it over 70 degrees but it's one hole at 3050 fps. I tried ten other powders and no luck.

Hodgdon lists 24.3gr CFE223 w/77's as MAX.! You are in dangerous territory there!

KRC · Nov 22, 2018

Powder charge weights are accurate . . .

With the smaller chamber and case volume, I would not be surprised if I am developing 24.0 gr.-like pressures with 23.7 gr. Varget. I have seen no significant pressure signs yet.

My next loads will be with bullets seated further out, how long an OAL with the modified magazines is TBD. This should also get the bullet closer to the lands (.223 Wylde chambering), so this may help with precision as well.

Testing continues, but these 10-20 mph switching winds are limiting useful load development range time.

paxfish · Nov 22, 2018

KRC said:
Do you have fairly tight necks? (Do you know the diameter of your neck sizer?)
What precision are you getting at 100 yards?

I just do a full length resize every time, and trim to consistent length. I won’t list my group size, some hockey -puck will demand proof, then I gotta dig out my targets.

Do your ladders, and the answer will become clearer. Suffice to say, A well built Service rifle can shoot sub .5 moa consistently.

KRC · Nov 25, 2018

"Gold is where you find it"

Range Report - Success?

I only had a short amount of range time yesterday, but was able to try out some of the 77grn. SMK loads I’d worked up. Conditions were cold, with highly variable 5-15 mph winds.

With the combination of using LC brass (which seem to have a greater internal volume than Lapua), and the ~.060” longer cartridge OAL made possible through the use of the modified magazines, I was able to load more powder without excessive compression and bullets popping up than I had previously. Turns out I may not need it.

The last two 5-shot (100 yd.) groups measured about .431” and .324”, both shot with 23.4 grn. Varget with the OAL about 2.316”. I believe the longer OAL helps with the Wylde chamber with its extra freebore length relative to the standard .223 chambering. (The modified magazines functioned flawlessly.) By the tables, this should be about a 2500 fps load, not blistering, but good enough for the 600 yards I anticipate shooting at. Both H4895 and Reloader 15 loads were not impressive in prior testing, and were not yesterday either.

I am anxious to load more of the 23.4 Varget load to verify, focus further testing on 23.0 to 24.0 grn. Varget loads, and try some longer distances. Thanks to all who offered advice.

I have posted the targets from yesterday and an image of the modified magazines. Note that while the pattern is of an IBS 100 yard score target, this pattern has been reduced in size to fit a 8.5”x11” sheet.

paxfish · Nov 26, 2018

Good deal! It’s great to settle on a lead, and just focus on your shooting!

Park ranger · Nov 26, 2018

Are you planning on shooting service rifle/XTC? We single load 600 yard slowfire, so no need to worry about mag length.

KRC · Nov 28, 2018

I'm relatively new to the AR-15, and have no plans to compete. I had to look up "service rifle/XTC". Sounds like fun, but I'm not sure I want to do much shooting where I have to actually HOLD the rifle up. (Older, greyer, balder . . . . )

I am disappointed that I've loaded for these rifles for 2 years and not known about getting the extra cartridge length by modifying the mags. Although further testing is needed, it seems like this is a major factor in improving precision. I only came across this information researching the 224 Valkyrie, where "window mags" were discussed.

77gr SMK load

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