6 Grendel 107 SMK Load data

[Lawrence97]

Klem,
I forgot to answer your question in regards to Case capacity. The 36gns of H2O that is published online is Case capacity to overflow (water to the top of neck) and this equates to a useable 30.5 gns since you don’t want powder in your case neck.

[Lawrence97]

Grayfox,
I agree with you that 0.5 gns might be too course for this particular case size. I tested in 0.5 increments to find the upper limit with minimal components and firing 5 rounds allowed me to gather some velocity data vs just using 3 round groups or a ladder test that might not repeat. Now that I have narrowed down some powder ranges I will test within those limits using .2-.3 gn increments for fine tuning.

[Lemonaid]

I think the normal magazine that allows the the longest OAL is ASC. I routinely load to 2.290 in them. Next is C Products Defense and shortest is E-lander. I have been thinking of modifying my E-lander into something like in the link below.
https://www.cavitybackbullets.com/produc...od-mag.htm

https://www.precisionfirearms.com/48m8/m...-mags.html
https://www.cheaperthandirt.com/parts-an...?q=grendel

[Bat Rastard]

https://gunmagwarehouse.com/asc-6-5-gren...azine.html

[flatland1]

Lawrence97,

I've been shooting AR15s & bolt rifles chambered for 6RAT for several years, although I don't recall shooting at 100yds for group with any of the heavier bullets. All but one of my bbls were 24" long (the exception being a Bartlein 28" on a match rifle upper), and most liked Berger 105VLDs better than S107MKs. Just reviewed chrono data, and even in the 28" bbl, best velocities/best accuracy were with H4895 at 2750fps. I ran as much as 30.1grs of RL15, but that gave obvious pressure signs, at an avg vel of 2840fps. I used this upper in XC Hi Power matches, so max range was 600yds, and this is the distance I normally tested all my heavy bullet loads at. Since 600yd stage is slow prone, all the heavy bullet loads for this upper were seated w/o regard for mag length limitations, and single loaded with a SLED.

I have had good shooting with S95MKs (not the poly-tipped version), seated to mag length, mostly out of a 24" Krieger 1-8tw bbl I contoured & chambered for a series of practical/tactical matches, where all ammunition was mag fed. RL15 & Wolf SRM primers gave VG accuracy at just under 2750fps; I've seen these bullets perform pretty well with other powders, but believe RL15 gave best accuracy. Downside is that RL15 is temp sensitive. Even in a Howa Mini bolt rifle with a 24" Bartlein, I'm not getting significantly higher velocities, although this little rifle has shot consistently better groups at 600yds than any of the several AR15 6RATs I've built & shot. As you're probably aware, the RAT has the body blown forward about .700", and with reduced body taper & 40* shoulder, probably has from 3.5 to 4grs more case capacity than your 6 Grendel, so this is hardly an apples-to-apples comparison. Just wanted to toss this out there to perhaps mitigate your apparent disappointment with lower velocities than expected, if that indeed is the case.

[Javman]

You need to get the PRI modified mags!!!

[Javman]

Lemonaid,

Please share or provide a link to magazines that will allow seating longer in an AR15 platform. If there are some out there I’d gladly purchase. I am currently using an E-lander magazine and it only allows 2.260 COAL.

You need these! Bought the ones for my 6.8 and have worked great in my 6.5GR.
https://www.cavitybackbullets.com/produc...d-5.56.htm

[A5BLASTER]

You need these! Bought the ones for my 6.8 and have worked great in my 6.5GR.
https://www.cavitybackbullets.com/produc...d-5.56.htm

I can do the same thing to a grendel mag with a hacksaw, needle nose plyer's and a round file in 5 mints or I can do it quicker with the dremel and a cut off wheel.

[Javman]

I can do the same thing to a grendel mag with a hacksaw, needle nose plyer's and a round file in 5 mints or I can do it quicker with the dremel and a cut off wheel.

Tried that myself and found the mags weren't as sturdy.

[Lawrence97]

Javman,
I have some PRI modified mags that are 10 rounders but they only hold 9 rds of 6 grendel. I have some 15 rounders on order.
You are correct, these modified mags are very sturdy and do not flex. I could see a regular Grendel mag modified with a hacksaw as having too much flex.

However, When running my pri modified mag and trying to get my 107’s to jam, I noticed my bullets want to plunge straight into the feed ramp and don’t want to ramp up into the chamber. Once I jump them a tad they seem to feed fine out tod the mag which defeats the purpose of having the modified magazine.

Did you have to modify your feed ramp at all when trying to jam into the lands ?

[Javman]

Javman,
I have some PRI modified mags that are 10 rounders but they only hold 9 rds of 6 grendel. I have some 15 rounders on order.
You are correct, these modified mags are very sturdy and do not flex. I could see a regular Grendel mag modified with a hacksaw as having too much flex.

However, When running my pri modified mag and trying to get my 107’s to jam, I noticed my bullets want to plunge straight into the feed ramp and don’t want to ramp up into the chamber. Once I jump them a tad they seem to feed fine out tod the mag which defeats the purpose of having the modified magazine.

Did you have to modify your feed ramp at all when trying to jam into the lands ?

So far I haven't had any issues that you mentioned other than having to load the 9 rounds also, but I'm running the GB 20"Monster barrel and it doesn't take much to kiss the lands. I'll be working on some loads for my RAP as I have quite a bit of room before getting close to the lands. I'll keep you posted.

[Lawrence97]

Thanks for the update. Mine when loaded long in the pri magazine definitely want to ram/nose dive straight into the feedramp

[biodsl]

I think the normal magazine that allows the the longest OAL is ASC. I routinely load to 2.290 in them.

ASC used to mention this as a selling point on their website. It doesn't seem to be there any longer.

[HomeSlice]

I’d suggest trying some better brass, such as Lapua.

My story: I had a 6fatrat space gun upper built for across the course. I hydroformed my brass. My initial loads were hornady brass and the hornady 87. Didn’t shoot very well and the chrono numbers sucked, like your do. Next was the 95smk in hornady brass. Shot a lot better, but still not very good numbers.

I bought a box of Lapua brass, hydroformed, and loaded the 110smk for 600. The thing was a laser and had an sd of 4 and es of 11 across 2 10 round practice targets. For shitsandgiggles, I loaded some of the 95s into the Lapua brass and got single digit SD and mid teen es.

I ended up settling on the 95smk in hornady brass with h4895 for my short line stuff, because I had a ton of the hornady brass and it shot well enough for me in those positions.

Just something to think about before you give up on the barrel or the 107. My barrel is a 7twist 26” Krieger fat rat, but for my chrono numbers, the brass made a huge difference,

[Herzo]

Out of curiosity, I ran the numbers for this bullet through Berger's stability calculator -- a value of 1.5 or greater is what they suggest as adequate stability. They give 1.44 for this bullet in a 1:8 and 1.89 for a 1:7 twist. It may be that your barrel doesn't like that bullet.

I found the sweet spot in my 28" - 1:7 barrel with the bullet touching the lands.

[Es 350]

I’d suggest trying some better brass, such as Lapua.

My story: I had a 6fatrat space gun upper built for across the course. I hydroformed my brass. My initial loads were hornady brass and the hornady 87. Didn’t shoot very well and the chrono numbers sucked, like your do. Next was the 95smk in hornady brass. Shot a lot better, but still not very good numbers.

I bought a box of Lapua brass, hydroformed, and loaded the 110smk for 600. The thing was a laser and had an sd of 4 and es of 11 across 2 10 round practice targets. For shitsandgiggles, I loaded some of the 95s into the Lapua brass and got single digit SD and mid teen es.

I ended up settling on the 95smk in hornady brass with h4895 for my short line stuff, because I had a ton of the hornady brass and it shot well enough for me in those positions.

Just something to think about before you give up on the barrel or the 107. My barrel is a 7twist 26” Krieger fat rat, but for my chrono numbers, the brass made a huge difference,

You wouldnt have a H2O capacity on the Hornady vs Lapua brass would you?

You probably saw my post (below this one at the moment) on 22Grendel IMP..... I started with Hornady brass and what i am still shooting just to get a feel for case life.
I read of a guy that tested most Grendel/PPC brands of brass, his conclusions was Norma was the toughest.

I originally was going to get some Norma 22 PPC brass and have since done so , (after reading about the above test) while i have fireformed 10 pieces to compare capacity vs Hornady i have not really tested it as far as load development.

What i can say is it is MUCH more consitent case to case than Hornady and offers .8 gr more H2O capacity after 2 firingings on Norma.