6mm Creedmoor

[Stats Shooter]

I just bought a Bergera HMR 6mm Creedmoor.

There are a few makers out there making cartridges including Hornady, Starline, Petersons, and Lapua. Lapua is Small pocket only, starline and Petersons give you an option between LR and SR pockets, and Hornady is LR only.

I guess I have not really thought about using SR primers in what would traditionally be a LR pocket. I know Palma shooters have done it for years now but I have no experience there. I want to buy Lapua but am not sure about SR primers for a hunting rifle.

Anyone done any testing on this? What are the proven advantages/disadvantages? Since it is a hunting rifle, ignition under various conditions is more important than a slightly lower SD or something.

 

[kilotanker22]

In a smallish cartridge like the Creedmoor. I don't think that you will have an issue. Especially with powders that give good case fill. I would also guess that you would see good SD

 

[hounddawg]

Go SRP if you are loading for speed, either one works for accuracy. Are you planning on running hot loads ? If so I would go with the SRP cases, that's what they were designed for. Originally Palma shooters used them to push .308 Win out to 1000 yards without going trans sonic. In .308 and in .260 Remington I have used both. Just develop the load for which one you choose and realize if you switch to the other style brass you will need to fine tune a bit

Alpha Munitions makes good brass also, I am using their LRP 6CM brass and it was quality brass out of the box. Peterson and Lapua is good stuff also if you want multiple reloads. If you are going to be losing the brass in tall grass or shooting no pickup matches then get the cheap stuff otherwise you can't go wrong with any of the good stuff

 

[Bfglowkey]

SRP use in the 6 or the 6.5 Creedmoor for that matter is dependent on the type or powder and pill you will use. If you decide to dabble in the heaviest of the bullets with the slower burning powder ( anything long the line of Superformance and slower ) you will see much better results using LRP and magnum primers. If you stick to the traditional ( H4350, RL16 , IMR4350 ) SRPs work fantastic. Using Magnum Small Rifle primers is completely up to you. That has been my experience reloading for these cartridges.
Side note: I had some very good results using H1000 and the 110 SMKs.

 

[std7mag]

The use of small rifle primers started and is still used by benchrest shooters, and F-Class shooters.
These guys push the limits on pressures, and have found they can raise the pressure with the small primer.
For a hunting rifle that you want to go bang when it's 72f and raining, or 15f and snowing i use the Fed210M.

 

[Rimfire5]

I've tracked the accuracy of my 6.5mm loads based upon primers over 1198 measured groups and have found the following.

Small Rifle Primers: (Lapua Brass)
CCI BR-4 - best accuracy
CCI 400 - 10.6% larger average group size at 100 yards.
Fed 205M - 47.9 larger average group size at 100 yards.

Large Rifle Primers: (Norma and Hornady Brass - 0.001 difference in average between the two brass types - no measurable difference due to brass)
Fed 210M - 20.6% larger average group size at 100 yards.

 

[RC20]

Have you adjusted powder loads to see if that changes the group sizes with the other than BR-4 Primers?

And or is there a velocity change that takes you out of the node?

 

[Stats Shooter]

I knew about the longevity of primer pocket theory, and again this is an antelope (and possibly coyote rifle). So while we all want tiny groups, winter ignition in North Dakota is something to consider. Right now it is -8....Common during the night when we would hunt coyotes it will be sub zero. Antelope season in the Cowboy state is more like October so that's not frigid.

The powder I am leaning towards is H4831 SC and the 105 gr Berger Hunter Hybrid. Or the Hornady ELD-x 103 gr. Anyway, my point is, would a small primer be as reliable in the cold with a case with a volume that would traditionally warrant a LP. Would they be as accurate @ 25 degrees as they are at 75 degrees. Or rather, as consistent.

 

[Rimfire5]

RC20
Velocity range of the loads during the testing was 385 fps.

Stats Shooter
H4831 is an extreme powder and is temperature insensitive and a good choice for cold conditions.
You are experiencing temperatures low enough to keep me in the lodge.
I have experimented in the cold (around 19 deg. F.) using magnum and regular primers for my .270 with large rifle primers.
I found magnum primers increased muzzle velocity by about 12 fps and resulted in a slight improvement in group size and little difference in POI. That would indicate to me that the magnums probably might have made the burn more consistent in the cold.

If you are concerned, you might give magnum primers a try in those really cold conditions.

 

[Bfglowkey]

RL16 seems to be very temp stable compared to its RL 17 brother ( share very similar burn rates ) H4350 is solid and easy to tune for also Temp tolerant.
I dabbled with the H4831 C and it had promise. Groups were solid but my spreads were not as good as RL 16 or 4350 so I abandoned it. For your cold situation...develop with the magnums....I hunt in Canada in similar temps.

 

[hounddawg]

this is a slowpoke load, only 2800 FPS. Load is not really developed yet, I did a rough load test and a rough seating test for barrel break in then shot it in a match. These were rounds 120 - 140 down that barrel

107 SMK and H 4350, I wish that scope had a 1/4 Moa to the left click on it

 

[std7mag]

BFglowkey,
If you shoot year round like i do, any "temp instability" is taken care of on your dope sheet.

OP,
With the 6CM having about the same capacity as the 243, you might want to give RL26 a try.
Performed great for me in the 243 with 100+ gr bullets.

 

[Stats Shooter]

I think I'm going to just stick with LR primers. As for the powder, I really want 4831 to work. I use 4831 SC for 270, 6mm Rem Improved, and light weight 300 am bullets.

Also, my 6mm CR has a 26" barrel, plenty of barrel for a slower powder. Plus the SC version allows me to stack more in the case......another reason I guess I will use a LR primer

 

[hounddawg]

I think I'm going to just stick with LR primers. As for the powder, I really want 4831 to work

make a development thread or update this one when you do, I have about 5 pounds of 4831 and it worked really well in one of my .260 Rem barrels so I am curious to how it works for you in the CM

 

[hounddawg]

made it to the range yet Stats Shooter ? I have about 180 of the 107 SMK's left. After 300 rounds I am going back to finish my load tweaking with the H4350. and use the rest to try some 4831SC later this month.

I just loaded up 25 rounds going from 40.0 to 42.0 as per Sierra load data. 39.5 shot well including a 196 10X at 300, but at 800 I averaged about a 1 MOA vertical spread and I would like to cut that down to .75 or even .5

 

[RC20]

I don't shoot 6mm. I do shoot a lot and have shot in sub zero with 4831 and regular primers.

Never had any issues. At times I have shot better cold than on a nice day. That could be better cushion and hold aspect but the rounds worked fine.

H4831 is less temp sensitive, its not insensitive. You might have to increase a tad to stay in a node if you developed it at warmer temps.

If its on the hot end then you want to be very careful or not shoot it at the higher loads.

 

[Bfglowkey]

Std7mag: I agree on the Dope card. I have a whole rolodex filled with cards for my rifles/loads in 10 degree increments ( hunting loads...5 degrees for my accuracy/target loads) as these tend to be good for the application at hand in terms of acceptable accuracy.

If you keep it simple I think all will be fine. We like to over think things sometimes and I am guilty on more then one occasion per day. My only re-attack is to pay close attention to your first shot/col bore shot once you close in on your load. Since that tends to be what matters most when the meat is in the cross hairs.

 

[Stats Shooter]

I have not made it to the range yet. Right now there is 40" of snow, the temps averaged around -3 for the high, and the wind chill is between 30 and 50 below zero.

I have purchased the 105 gr Berger hybrid hunters, and I am using lapua Small rifle primer brass. When I get the chance, I will be using that 4831 sc, to see what it will do. I'm going back to the family farm in a couple months where we have a 1k yard range and I will have some promising loads by then (I hope).

My F-Open 300 am has about 1/2 moa vertical spread at 1k, while my 6mm AI has about 1/3 moa vertical with the 110 smk at 600 yards. The creedmoor doesn't have the twist for that bullet, and it isn't a hunting bullet anyway.

 

[std7mag]

Twist, schmist..
The bumble bee and supposedly the F4 Phantom are proof that if you push it fast enough it will fly.

North Dakota??!!
What the heck were you thinking??!!

 

[Stats Shooter]

If I wasn't such a wimp I would just prone out in the snow, but that doesn't seem like fun. I have access to a 100 yard underground range, but I like to do load development at 300 yards so I am 90 days away from being able to do that.