Load Development for Service Rifle

[mtncwru]

I'm finally getting around to working up a load for my Service Rifle. Is there anything that I should do differently from my bolt gun load dev? I wasn't planning on chasing seating depth (since I need a mag length load), but beyond that are there any caveats to worry about or watch for? I'm planning on starting low and working up on powder charge, of course.

 

[Jeff Porter]

Don’t do it.
The work for a 20” heavy barrel gas impingement AR with a Wylde chamber has already been done.

What powder and bullets do you have ?


Most SR shooters will run 77 gr HPBT
24.0 Varget , 23.2 8208, 23.4 H4895
N135, N140 at 2.250” COAL ( mag length ) will be 0.75 moa in 90% of match prepped SR’s. 10 ring is 2 plus MOA on SR, SR3 and MR targets.

80’s single loaded may gain you some X’s at 600 but the mag length 77’s will clean 600 just as well.

It is a big target. Spend your time working on offhand, not at the loading bench.

Got me to HM,DR and P100 .. your turn now.

 

[mtncwru]

Don’t do it.
The work for a 20” heavy barrel gas impingement AR with a Wylde chamber has already been done.

Yeah, I wasn't planning on anything terribly extensive for load dev, just checking that my powder charges weren't yielding unsafe pressures. And to your point about single-loading 80s for 600 yards, I'm a huge fan of having one load whenever I can. One less thing to keep track of on the firing line.

What powder and bullets do you have ?


Most SR shooters will run 77 gr HPBT
24.0 Varget , 23.2 8208, 23.4 H4895
N135, N140 at 2.250” COAL ( mag length ) will be 0.75 moa in 90% of match prepped SR’s. 10 ring is 2 plus MOA on SR, SR3 and MR targets.

I have a giant pile of 77 grain SMKs, and 16 pounds of Shooters' World Precision Rifle that I'll be working through in Lake City brass. The powder manufacturer lists a max load of 23.0 grains for an SMK 77, and my only hesitation is the amount of compression that would result in with a 77 seated to mag length, even with my drop tube.

 

[Jeff Porter]

SWP is very similar to Varget and N140. I would guess you will get closer to 24.0 - 24.5 gr with minimal “crunch” with the 77 SMK before you see any flat primers or ejector swipes. ( Assuming you have a Wylde chamber ). CLE or standard .223 chambers will peak out a bit lower. One other caveat is the groove diameter of your barrel. 0.219” peaks faster than a 0.218” but your velocity will still be good.

Since it seems you like to test …
Run a series of powder charges and see where you max out. Group size under 0.75 moa for 5 shot groups is good enough.

Then just because you may see an improvement, seat your final load in at 0.005” increments to 2.235”. SMK usually don’t care about seating depth but I found Nosler 77 and Hornady 75 would tighten up a little at shorter OAL.

One other suggestion. AR was not designed as a bench gun. Be very diligent about consistent placement on the rest.

I would typically shoot sling from prone with a bag in front of my front hand better than from the bench.

You shoot the last 20 shots of an 88 shot string at 600. Don’t be too fussy about scrubbing your bore as it and your load have to work dirty.
When you do deep clean, hit the throat hard to knock down any carbon ring. I will JB paste every 300 rounds or so with Wipeout foam in between.

 

[mtncwru]

SWP is very similar to Varget and N140. I would guess you will get closer to 24.0 - 24.5 gr with minimal “crunch” with the 77 SMK before you see any flat primers or ejector swipes. ( Assuming you have a Wylde chamber ). CLE or standard .223 chambers will peak out a bit lower. One other caveat is the groove diameter of your barrel. 0.219” peaks faster than a 0.218” but your velocity will still be good.

Thanks for that! I do have a Wylde chamber, and I'll double check what my grooves are. It's a standard White Oak upper so I'll ask them if I can't find it elsewhere.

One other suggestion. AR was not designed as a bench gun. Be very diligent about consistent placement on the rest.

I would typically shoot sling from prone with a bag in front of my front hand better than from the bench.

You shoot the last 20 shots of an 88 shot string at 600. Don’t be too fussy about scrubbing your bore as it and your load have to work dirty.
When you do deep clean, hit the throat hard to knock down any carbon ring. I will JB paste every 300 rounds or so with Wipeout foam in between.

Noted! That's how I like to test ammo when I do, since it more closely matches what I'm used to, and can get more consistent than I ever can on a rest or bipod, even with my match rifle.

Since it seems you like to test …
Run a series of powder charges and see where you max out. Group size under 0.75 moa for 5 shot groups is good enough.

Then just because you may see an improvement, seat your final load in at 0.005” increments to 2.235”. SMK usually don’t care about seating depth but I found Nosler 77 and Hornady 75 would tighten up a little at shorter OAL.

Oh not at all, I hate load development. Between the hour drive to my nearest outdoor range, my kids, and my full time job range days are incredibly limited. I would much rather be spending my range time actually shooting for training (and my home time working on SCATT or dry-fire) instead of spending time making ammo. I shot smallbore for years before ever picking up an MR/LR prone habit, and my favorite kind of reloading is still the kind where I just open a new box of ammo and put another round in the gun.

My hope with asking the question was to keep my range trips for load dev to a bare minimum, and your advice here is exactly what I was hoping to find -- thank you SO much!

 

[Walt Krafft]

Your range time for load developement for xtc should be zero until you are shooting 195 and better standing. And by then you will know it is not needed.

 

[over_thetop]

I didn't see anyone talk about headspace for sizing cases and OAL bullet seating. Keep it loose for function. Bolt guns have more camming power than a gas gun. Also you could load at the range.

 

[Fishjager]

This is a load that I came upon recently and have shot it out of my White Oak upper 1 in 8.
Lake City Brass, 77gr Sierra BTHP, 23.3 grains of Vit N140, COL 2.26. 1.180 CBTO I used Federal 205's because that is all I had. Since then I managed to get some Federal 205AR's at a good price. I also ran a check with the same load using 23.3 grains of Varget. The results were almost identical. The picture below is shot at 500 yards. The last shot got that darn flier.