Any Loading Recommendations 6.5 CM, 135 A-Tip?

[Texas10]

Got some initial loads for the new 135 gr. A-tip in 6.5 CM using 4831SC but haven't shot them yet, and today I found some RL16 at the local Bass Pro so going to do another load series using that.

Has anybody else had occasion to work up a RL16 load with the 135 gr A-Tip? If so, what are your findings?

 

[ormandj]

No, but I'm about to start in the next month or so, and will update with what I find. RL16 and 135gr A-Tip is my plan as well.

 

[Texas10]

Well, I've loaded up two different OCW development series using H4381SC and RL16 after I found 5 one pound bottles sitting on the shelf at the local Bass Pro this week, and snagged two of'm. Going to be a couple of weeks before I can get results, but will post here.

 

[Bc'z]

Well, I've loaded up two different OCW development series using H4381SC and RL16 after I found 5 one pound bottles sitting on the shelf at the local Bass Pro this week, and snagged two of'm. Going to be a couple of weeks before I can get results, but will post here.

Expect to see small groups with the h4831sc

 

[Texas10]

I would expect nothing less from the Secret Carolina load.

 

[FrankG]

Haven’t tried the others but H4350 just pounds ragged holes for me.

23” barrel and running them at 2810fps.

We just got another batch of bullets at the shop a couple of days ago.

Later, Frank
Bartlein Barrels

 

[Texas10]

Loaded up 8 different 3 shot groups for an OCW series using the 135 A-tip and both RL-16 and H4831SC and found 44.3 grs of H4831SC shot best. I also loaded up some 140 SMK's and 43.3 H4831SC and it shot nearly identical 3 shot groups, holes nearly touching at 150 yds. Next will be some 142SMK's and 43.3.

Edited to correct powder used.

 

[Kurz]

Loaded up 8 different 3 shot groups for an OCW series using the 135 A-tip and both RL-16 and IMR4831SC and found 44.3 grs of IMR4831SC shot best. I also loaded up some 140 SMK's and 43.3 IMR4831SC and it shot nearly identical 3 shot groups, holes nearly touching at 150 yds. Next will be some 142SMK's and 43.3.

I wonder if we would see anything more significant if the targets were at 300 yards. I love to see small knots of bullets holes but when I'm searching for the best refinement of some loads I move the targets back some more. Just a curiosity. (H-4831SC not IMR...)

 

[Texas10]

I wonder if we would see anything more significant if the targets were at 300 yards. I love to see small knots of bullets holes but when I'm searching for the best refinement of some loads I move the targets back some more. Just a curiosity. (H-4831SC not IMR...)

Thanks for catching my brain fart.

 

[Andy Legg]

Haven’t tried the others but H4350 just pounds ragged holes for me.

23” barrel and running them at 2810fps.

We just got another batch of bullets at the shop a couple of days ago.

Later, Frank
Bartlein Barrels

Working up a load for a 20” AR10. And I’m curious about seating depth for this 135 grain A-Tip. Bullet.

It’s being used in Mid & Long Range Prone Slow-Fire…so it’s single feed only (can be greater than mag length).

It’s kinda looking like 41.5-42.5 grains of H4350 with CCI#34 Primers.

Not really wanting to jam them into the lands, but I’m about ready to give it a try.

Frank-would you care to share your thoughts on this?

Thank You,
Andy Legg

 

[chromatica]

I did a quick workup using Gordon's Reloading Tool. With A-tip 135 over Reloder 16 in a 26 inch barrel, at
Max Pressure 43.5 gr RL-16 yields 2954 fps. You can download this as far as 38.5 gr and still get burnout inside the barrel (complete combustion) yielding 2635 fps. I would explore the interval between these two points.

Here's a caveat: I did load testing for 6 ARC (bolt action) using RL-16 and RL-15.5. With heavy for caliber bullets (105 grain) my measured velocities were consistently 200 fps lower than the simulations in GRT. I asked a buddy to crosscheck my calculations using his copy of QuickLoad. He got essentially the same numbers I did. I suspect that one or more of the thermodynamic properties for these Alliant powders is off in both the GRT and QL libraries.

 

[FrankG]

Working up a load for a 20” AR10. And I’m curious about seating depth for this 135 grain A-Tip. Bullet.

It’s being used in Mid & Long Range Prone Slow-Fire…so it’s single feed only (can be greater than mag length).

It’s kinda looking like 41.5-42.5 grains of H4350 with CCI#34 Primers.

Not really wanting to jam them into the lands, but I’m about ready to give it a try.

Frank-would you care to share your thoughts on this?

Thank You,
Andy Legg

What reamer spec cut your chamber/throat to? That would help to know.

 

[Andy Legg]

What reamer spec cut your chamber/throat to? That would help to know.

It nothing special, a 22” Ballistic Advantage 1/8 .936 Bull that I had cut down and recrowned by Omar Alonzo just before the NRA changed the AR Tactical rules to allow up to 22” barrels (to alignwith CMP rules).

The chamber/reamer should be a standard SAAMI 6.5 CM Spec.

I loaded some rounds to the Hornady Recommend 2.815” COAL for the 135 Grain A-Tip. By my measurements this put me at about 0.148” Jump. My second try at seating depth was at about 0.108 Jump. If I take it all the way out till the bullet touches, I will still have 0.330” of bullet remaining in the neck of the brass…. Even with the boattail, it appears have enough…. I also like to use a very light factory crimp (Lee Die).

Since this is an AR10 (floating firing pin) I have been using CCI#34 primers and working up loads of H4350 starting at 41.5 and working up to 43 grains in 0.3 increments. My best results have been around 41.8 & 42.1grain.

Note: AR-Tactical is a Slow Fire Prone Discipline….so all ammo is single loaded. Ammo does not have to be Mag Length .

I think I am going to go down to about 0.025 jump and give that a try.

I thought the 6.5 CM would be the ez button for long range (CMP has AR-Tactical matches at 1000 yards)…. But has not worked out yet. I also have an X-Caliber .243 Win. Barrel that’s is 1/7 twist. I may move on to try that here pretty soon with 106 grain A-Tips. I need to have something for my 14 year old to shoot at the Camp Perry Long Range Matches this summer.

Any thoughts or suggestions are appreciated.

UPDATE: I long seated a handful at about 0.015 Jam…. 41.8 grains look promising. Next I’ll try about .015 or .020” jump.

 

[FrankG]

Even the saami spec. chamber.... your throat sounds way to long for whatever reason but those numbers seem way off.

If your seating the 135ATIPs to 2.815" o.a.l. you shouldn't have a .148" jump. According to my numbers your about another .040" longer than what a Saami min spec chamber should be giving you.

Most people don't know there are also chambers used that are called production chambers. So what actual reamer was used is a guess on our part.

 

[Andy Legg]

Even the saami spec. chamber.... your throat sounds way to long for whatever reason but those numbers seem way off.

If your seating the 135ATIPs to 2.815" o.a.l. you shouldn't have a .148" jump. According to my numbers your about another .040" longer than what a Saami min spec chamber should be giving you.

Most people don't know there are also chambers used that are called production chambers. So what actual reamer was used is a guess on our part.

Finally got around to messing with this again.

It looks like Frank was spot on….I purchased another 6.5 CM Barrel (Criterion….the first one is a Ballistic Advantage). Lo and behold, when measuring for the lands with the same 135 A-Tip projectile…the new barrel has 0.043” less freebore than the Ballistic Advantage Barrel.

I’ll pick-up where I left off with the load development.

Frank-Thank You for pointing me in the Right Direction.

 

[ebb]

If you want to experiment, further try N160 or N165. I ran H4831 and IMR 4831 in a 6.5-284 long before there was such a thing as 6.5 Creedmoor, but the VV powders seem to work better, and cleaner.

 

[FrankG]

Finally got around to messing with this again.

It looks like Frank was spot on….I purchased another 6.5 CM Barrel (Criterion….the first one is a Ballistic Advantage). Lo and behold, when measuring for the lands with the same 135 A-Tip projectile…the new barrel has 0.043” less freebore than the Ballistic Advantage Barrel.

I’ll pick-up where I left off with the load development.

Frank-Thank You for pointing me in the Right Direction.

Your welcome bud!