Primer/Ignition Question


December 5, 2006, 03:27 PM

I recently found a load that I can FINALLY get to shoot out of my Rem 700 in 300 RUM, however it seems to be a bit inconsistent.

I just got back from the range today where I fired 30 rounds of the exact same load. Temps were about 50 degrees. I can put 3 rounds in the exact same hole at 100 yards without problem, however when I shoot a 5 shot group at least two of the rounds are "flyers". I can't really explain it. I KNOW it's not me, I've shot much bigger and badder, the shots feel good as soon as I pull the trigger, however when I look back down the scope I see a flier 1 inch away from the other 3 rounds.

I got to thinking about everything that would affect the situation. I know the mounts/rings are good. I know the scope is good. I know the stock/rifle contact is good. The load seems to be good as it will one hole 3 rounds; I mean groups in the .2's .3's CTC.

I moved over to the 200 yard range, same thing. Groups about .5-.6 for 3 rounds, but when I shoot 5 it opens the group up to 1.2-2.0

I was wondering, I had heard that Federal GM215M Primers were the "coldest" of the magnum primers. Any truth to this?

I've never experienced an ignition problem in a rifle before so I don't really know what to look for. I do know when setting off 98gr of powder it wouldn't be hard to get them. I was wondering if others are using 215M primers on big mags, or if they move to something a bit hotter say a WLRM?

The rifle is basically a factory stock 700 Sendero. I've glass bedded it, added an aftermarket trigger and tuned it down to about 1/2lb. I've got a Leupold 8.5-25x50LRT sitting on top.

The load I was shooting was:
165gr Nosler Accubonds
98gr H-1000
Remington Brass
Federal 215GM Primers
3.63 OAL

Questions, thoughts, comments?

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December 5, 2006, 03:37 PM
You can try a different primer, but odds are it won't make much of a difference.

I shoot with the same bunch of guys every Sunday and over breakfast in the range clubhouse recently, we had a discussion about primers. For the most part, changing only the primers in a specific load will change the point of impact of the group, but have little to no impact on group size.

I'm sure there's the occasion where a primer may results in better groups, but on average, it probably won't affect it.

Of course, it doesn't hurt to try.

I don't know of Federal being the 'mildest' of the magnum primers. But if you want better ignition, you could always try the CCI magnum primers.

I honestly think that your gun is shooting as accurate as it is. The fliers are you experiencing is probably just the natural result of the rifle over the course of 5 rounds. Try shooting 10 round groups. It will give you a better idea of where your rifle is.

When you test loads, you could also try waiting a few minutes before each round to see if that affects the group. Could be barrel heat affecting the later rounds in your group. Could be fouling.

There are always different factors affecting the 'accuracy' of a rifle besides the components.

December 5, 2006, 03:42 PM
Thanks for the quick reply,

I'd like to address some of your comments. The rifle was shot with a cold barrel for each shot.

As for fouling, I doubt it. The only reason I say this is because I could shoot a 5 shot group, then do it again, with the exact same results. This was the case from the first set of 5 rounds. The rifle does foul, but it's relatively little for a factory barrel.

December 5, 2006, 04:02 PM
If you shoot a 5 round group where the first 3 are touching and the next 2 are not, then shoot another 5 round group where the first 3 are touching and the next 2 are not without any cleaning between the 10 rounds, then all I can attribute it to is the barrel heat/flex/harmonics.

I doubt it's your load or components. A 2" group at 200 yards is very respectable, especially out of a factory barrel. I understand you'd like to get all 5 rounds in the group within that .2-.3". But sometimes the rifle just doesn't want to let you do it.

Personally, I'd stick with the load. Try a different primer just for fun, but I think the load is sound.

I don't want to discourage you from trying to eek out that .25MOA consistent 5-round group, but I don't want you chasing a ghost, either.

December 5, 2006, 04:10 PM

I really appreciate your responses. I know what your saying, it's a lot to expect from a factory tube/action but I think it's possible. I've "chased that ghost" before and yes it's tough, but at the same time I've had this exact same situation happen with another gun and after a year of trying I found a load. Now I probably have 500 rounds left out of the gun before it needs a new barrel and I have to start all over again.

Anybody else run into something like this?

December 5, 2006, 04:38 PM
Oh, just wondering, have you chronographed your loads? Might be worthwhile to chrono during group testing at 100 yards. Variance in velocity could explain fliers from the initial group.

December 5, 2006, 05:07 PM
I've chronographed many loads from this gun, but not this specific one. I'll put that at the top of my list.

December 5, 2006, 05:21 PM
Try fireing the 5 rounds quickly before the barrel gets hot. It does take a moment for the hot gases to throughly heat the barrel.

December 5, 2006, 05:26 PM
That's not goning work with the .300 Ultra. It gets hot FAST.

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