6.5 CM primers
- Thread starter BW64
- Start date
Large magnums will not do anything for you. Some people like to use small rifle brass as they say it last longer and in those cases they usually use a magnum small rifle primer to get it closer to a standard large rifle for the larger powder column.
You aren’t missing anything using large rifle primers.
You aren’t missing anything using large rifle primers.
I think it depends a lot on the powder you're using and the temperature setting your shooting in.
I don't shoot a 6.5CM, but with my .308 I find a SRP case with a magnum primer works really well for me here in the Phoenix area temperatures. I find when I use the Remington 7.5's, they're a pretty hot primer and seem to be very similar to a magnum SRP's. I've come to really like the 7.5's as I get pretty consistent results that have been slightly (very slightly) better than my "standard" LRP's.
Steve Donlon
Gold $$ Contributor
I have tried small rifle primers in Lapua Brass compared to large rifle primers in Lapua 6.5 Creedmoor brass and found I needed one grain more powder to reach the same velocity using small rifle primers.The large rifle primers are more accurate from what I have seen also. The only benefit I see from small rifle primers is that with hot loads, your brass might last longer from what I have read. This has been debated a lot and it might have some thing to do with the powder you choose to use.
Steve Donlon
Gold $$ Contributor
I went back and looked at my 6.5 Creedmoor ammo and remembered what happened to me. With 147 gr. bullets and IMR 4350 powder I needed 41.5 gr.s with a small rifle primer , #450's to match the velocity of 40.5 gr.s with a large rifle primer WW. If I went to 41.5 grs. of powder with the large rifle primer I got pressure signs. But with Berger 144 gr, bullets and Lapua brass I could go to 41.5 grs. of RL16 and get 2840 fps with large rifle primers. BR2. And after I enlarged the flash hole in Lapua SRP brass , I could get the same 2840 fps. using small rifle primers #450. So with that powder and the enlarged flash hole, they both shot the same. Same accuracy. Just find what powder and bullets works best and enlarge the primer hole in the SRP brass and they are more alike than different.
Last edited:
This does not involve a 6.5 CM, but it does involve a comparison between large and small primers. A gunsmith and fellow BR shooter shot a 6BR in short range competition. This would have been in 1979 or '80. Of course, back then, there was no 6BR brass available and you had to form it yourself or pay someone else to do it. In this case, he formed 50 from the Remington basic BR brass (308 with a small primer pocket), and 50 more from 22-250 brass (LRP, of course). He shot LV with one batch and HV with the other. By the end of the year, his season aggregate was virtually the same. This led him to believe it didn't really matter.
The increased case capacity of the CM case might make a difference in favor of the large primer, but I wouldn't bet on it. I use LRP brass and have no reason to try anything else. I believe the one rifle (a post-64 Model 70) would need to be bushed to use small primers. Reason enough to avoid them, I think. WH
The increased case capacity of the CM case might make a difference in favor of the large primer, but I wouldn't bet on it. I use LRP brass and have no reason to try anything else. I believe the one rifle (a post-64 Model 70) would need to be bushed to use small primers. Reason enough to avoid them, I think. WH
The CM is not a BR type case using fast powders such as 4198 down
thru n-133 and the faster LT's.....It's using mainly a mid range powder
in the area of R-16, thru H-4350. Even if your shooting a lighter bullet
and using a powder in the Varget range, use the LRP under those heavier
charge columns......Shorter hunting barrels and especially in cold temps
will be better off with the LRP to get them slower powders lit.
thru n-133 and the faster LT's.....It's using mainly a mid range powder
in the area of R-16, thru H-4350. Even if your shooting a lighter bullet
and using a powder in the Varget range, use the LRP under those heavier
charge columns......Shorter hunting barrels and especially in cold temps
will be better off with the LRP to get them slower powders lit.
I use SRP's with my 6.5CM out to 1115yds. In winter when it's real cold I will use SRP magnums even though the H4350 is not really temp sensitive. I bought them during the shortage and just trying to use them up. I really like match primers because weights are very consistent compared to regular SRP's. I don't notice any real difference though regardless of what primer I use.
MikeRu
Gold $$ Contributor
I have had good luck with Fed 205M SRPs and H4350, for several 6.5 CM barrels. If problems getting groups I would probably try CCI450 first.
For what it's worth, about 4 years ago I did a primer test on my 6mm Creedmoor.
My load was 40.6gr, H4350, 105gr Hornady Eld match and starline brass.
I tested all the different primers I had on hand and loaded up rounds of each primer.
At the 1000 yd range we had Silver Mountain electronic targets. The target showed what the FPS was for each round at the target.
As you can see the average velocity from high to low was 25 FPS between all primers.
I did this test at the time some primers were difficult to find on the shelves and wanted to know if I could not get say CCI#41, I could use a different primer without any big differences.
This is my findings and may not be accurate for all others. I post this just for info only.
My load was 40.6gr, H4350, 105gr Hornady Eld match and starline brass.
I tested all the different primers I had on hand and loaded up rounds of each primer.
At the 1000 yd range we had Silver Mountain electronic targets. The target showed what the FPS was for each round at the target.
As you can see the average velocity from high to low was 25 FPS between all primers.
I did this test at the time some primers were difficult to find on the shelves and wanted to know if I could not get say CCI#41, I could use a different primer without any big differences.
This is my findings and may not be accurate for all others. I post this just for info only.
SHOT | #1 | #2 | #3 | #4 | #5 | #6 | #7 | AVG | SD | | |
| WINCHESTER | | 1365.00 | 1340.00 | 1324.00 | 1328.00 | 1336.00 | 1338.00 | 1294.14 | 1332.00 | 19.53 | |
| CCI 450 MAG | 1342.00 | 1317.00 | 1323.00 | 1343.00 | 1359.00 | 1311.00 | 1312.00 | 1329.57 | 18.50 | ||
| CCI 400 | 1331.00 | 1320.00 | 1328.00 | 1319.00 | 1346.00 | 1345.00 | 1320.00 | 1329.86 | 9.60 | | |
| CCI #41 | 1327.00 | 1351.00 | 1344.00 | 1305.00 | 1368.00 | 1339.00 | 0.00 | 1339.00 | 22.80 | | |
| FED 205M | 1296.00 | 1285.00 | 1346.00 | 1311.00 | 1329.00 | 1280.00 | 0.00 | 1307.83 | 24.60 |
Last edited:
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.