6XC - Reducing group size - bullet points?

[Kingfisher]

So now that I've had a chance to put some rounds down range I want to start doing some fine tuning. Since this is my first go round with a serious precision rifle, I thought I'd see if some experienced folks could give me some bullet points. I've done as much reading as I can stand but what I'm looking for is the biggest bang for the buck without a lot of hassle. If hassle can't be avoided, then I'll do what needs to be done. The gun shoots more consistently than any gun I've ever owned. The ugliest group I've shot was still under an inch, but my goal is for it to consistently shoot 1/2 that.

The only combo I've tried is H4350 with the HbN DTAC's. This is out of a 29" Bartlein 1:7.5 with a .2748 neck. Brass is Norma 6XC. With 39 grs I was finally able to get to 2900 fps. but I'm hesitant to run any higher. I need to make a modified case so that I can really nail down the proper OAL, that's at the top of the list. I've also only tried .5 gr increments on the powder.

Do I really need to fine tune with .1 gr. increments or should I got larger? (Will I be able to see the difference)
Will neck turning shrink my groups considerably?
Adjust OAL closer/further?

Any other big hitters that I'm missing?

 

[dtucker]

If your chamber is set up as a no turn neck and you are using good brass then i would not be wanting to do anything to my necks. I work my loads up in .3 increments and start my load developement with my bullets seated into the lands and not just touching as i do not go through and measure bullets from base to ogive. If i find a promising spot i will adjust my seating depth to see if they tighten up. I load for custom varmint rifles and do not bench shoot any more so i do not go to the extreme as i used to. I will already have in mind what bullet weight i want to shoot and will usally try about 3 different bullets in the same weight. Once i find what i am wanting i may try a different primer. I have found through the years that their are a couple go to powders for any of the cartridges you load for and finding a accurate load in a well built custom rifle has never been a challenge for me.

Good luck,
Dan

 

[Kingfisher]

Thanks Dan, I figured (and hoped) that someone would say as much. I definitely think I've got some work to do in the OAL dept. I think that's definitely going to help with the consistency. Like I said, the gun obviously shoots and I think I can trim the groups down and get the consistency that I'm looking for, I just want to make sure that I'm focusing in the right places. I built the gun up to run the DTAC's but I might also try the Bergers. In the meantime I'll keep tinkering.

 

[Nomad47]

I'm running 105 grain hBN coated Amax bullets in two 28" 8 twist Criterion barrels. I found RL-17 to be good and IMR 8208 XBR to be even better. Fed 215M primers for both powders. Bullets are seated .021" off the lands.

 

[willey_coyote]

I have built several 6xc for friends and clients. almost everyone shoots 1/4' groups at hundred yards with the same load. 39.0grains of h4350 and the berger 115 VLD. at 10 thousands off the lands. with a federal 210 primer. For my personal gun i shoot the 107 matrix bullets out of canada. VERY ACCURATE. 41.0 grains of h4350. Good luck. it is a supper fun round.
shawn

 

[Kingfisher]

Excellent. Thanks gentlemen. Hopefully I can find a load w/ H-4350 considering I just ordered 4lbs of it. lol Considering some of the groups I shot just breaking in the gun, the potential is certainly there. I do think the proper OAL is going to be key. Once I lock that down I'll adjust the powder up and down a bit and see what happens. The OAL's I got just using a loosely fitted case and measuring off the meplat (I know... wrong) gave a .01 spread, obviously I don't think the ogive on the DTAC's was that far off from bullet to bullet. I've got the Hornady gage for the calipers. Next up is the modified case for the OAL gage. Just have to form some old 22-250 brass so that I don't have to trash one of my Norma 6XC cases.

 

[PALarson]

I have been shooting 6-XC for a couple years. I tried H4350 and it was quite good, I figured that the 6-XC was more or less a 6BR XX so I tried Varget. Well I have won several matches and am always in the hunt. Saturday I shoot a 600-38 with my 6-XC and Varget. Very hard to beat. Chrnos at around 3200. I am using TS2 coating so that does somewhat very the load say as to a naked bullet. Try Varget sometime, you might really like the results.
Paul Larson

 

[WyleWD]

I have been shooting 6-XC for a couple years. I tried H4350 and it was quite good, I figured that the 6-XC was more or less a 6BR XX so I tried Varget. Well I have won several matches and am always in the hunt. Saturday I shoot a 600-38 with my 6-XC and Varget. Very hard to beat. Chrnos at around 3200. I am using TS2 coating so that does somewhat very the load say as to a naked bullet. Try Varget sometime, you might really like the results.
Paul Larson

Well halleleuyah!! Someone else has found that there IS something to use for powder in a 6xc. While not a big Varget fan myself..... have found R-15 to be particularly useful in the 6xc with coated bullets too and with winning results. Good on you for thinking outside the box a bit. Good shooting on that 600-38 score too by the way. Congrats. WD

 

[Kingfisher]

Good to know fellas. Now I'm almost wishing I didn't have 4 lbs of H-4350 on the way lol. It's good to know that there are some folks though that have in fact reinvented the wheel and been successful at it. From what I've read in terms of velocity, I'm really surprised that my velocities are as low as they are. I've only been able to get a hair over 2900 fps. with HbN DTACs and 39 gr. of H-4350 out of the 29" tube on my gun and everything I read has me thinking I should be well in the neighborhood of 3000 fps (or more). As I mentioned before, I'm realistic, so if it's a slow gun, then so be it. Just seems like I should be getting more speed out of it. Hopefully someone with a similar barrel length can confirm/deny. UNFORTUNATELY powder around here has all but dried up. A couple of weeks back when I was in Cabela's they had RL17 on the shelf and OOOOOH I was so close to buying a canister or two (they had Varget right next to it). Against my better judgment I didn't buy either. Now I'm wishing I had.

I've been looking back over my targets and honestly none of them are bad, but I definitely think that the potential is there for them to be considerably better. I think the seating depth may just make the difference. The appropriate tap to make some modified cases for the Hornady tool arrived today so I should have a much better idea of proper seating length here very shortly. I also was reading one of the articles on the site where a few folks had decent luck with H-4831 as well, so I'll give that a try just to cover all of my bases.

You guys let me know if you think of anything else.

 

[racesnake]

I've been using H4831SC behind an HBn DTac and getting 3150fps, with an ES of12fps, and no signs of excessive pressure. So far groups have agged in the 0.3 MOA neighborhood.
For the 105-108 bullets I use IMR4350. H4350 was not as accurate in this particular barrel. The 105 Berger VLD's shoot best. Right now they are agging 0.1-0.2 MOA. @ 3215fps. This load is a little hotter than the above, pressure-wise, but still OK.

 

[Kingfisher]

I've been using H4831SC behind an HBn DTac and getting 3150fps, with an ES of12fps, and no signs of excessive pressure. So far groups have agged in the 0.3 MOA neighborhood.
For the 105-108 bullets I use IMR4350. H4350 was not as accurate in this particular barrel. The 105 Berger VLD's shoot best. Right now they are agging 0.1-0.2 MOA. @ 3215fps. This load is a little hotter than the above, pressure-wise, but still OK.

Good to know, thank's for the info. I've settled on a load temporarily, if for no other reason but so that I can get out and shoot without going nuts managing everything down to the most minute detail. I've run all the way to 39 gr. of H-4350 but went ahead and dropped back to 38 gr. and did some OAL testing. I worked my way in from .0030 out (since I had some at that length already) all the way to jammed. For the most part the groups were consistently small, to the point where it's hard for me to tell the difference. However at .005 and jammed, I saw changes that I don't normally see. at .005 the first two shots ran through the same hole, and the rest formed up a nice tight little dime sized cluster (still think the gun will do better). The rounds that were jammed had a couple of fliers (which doesn't happen) and the group was one of the largest this gun has produced. Also, the ES at .005 would've been single digit except for one round out of the 5. The jammed rounds had a much wider ES. When I moved in closer to the lands I also picked up a little velocity, with the loads ending right at the 3000 fps. That's still not as much as I was expecting out of the 29" barrel, but better than the 2800's I was seeing when I started load development.

I've got some RL17 coming in today via UPS that I'm going to try. I've also entertained the notion of trying the 105 and 115 Bergers. It seems like a lot of folks are fond of the 105 Hybrids. I should be able to run the 105's a hair over 3100. As for measuring group size, I'm still figuring that out... this gun shoots consistently smaller groups that just about anything I've ever owned, so that part is new to me as well.

Fortunately, in the meantime I've tested the DTAC's out to 1000 yards and they hold exactly with the ballistics I've calculated, so the BC has got to be darn close to the .585 they're quoted at. At 500, I'm definitely .75 MOA or less. 750 is about the same. 1000 has been tougher because the wind here lately has been crazy but when I can read/judge it correctly I'm still under 1 MOA.

 

[Bob3700]

Kingfisher,

The 6XC is perfect for shooting 105-107 gr bullets and H4350 is definitely the preferred powder.

I shot a bunch of Varget in the XC as well. Being faster burning, it won't give the top velocities that H4350 will but you said you are after small groups first. That said, I shot some great scores and won some matches at 600 yds using Varget and 107 SMKs.

For DTACS, the XC is up against the governor. You can run the 115s at 3000 fps but my primer pockets didn't last long. Maybe three firings and the brass was trash. There just isn't enough boiler room to consistently run a 115 that fast without paying the price in brass life. I'll take some heat for posting that but out of three different barrels chambered for the XC, that was my experience. I went to the 243 SLR and it will achieve those velocities with the 115s and H4831sc and good brass life.

If you want down range performance, look at the 105 Hybrids. Good BC and you can run them at 3000fps. Good combo for the XC for sure.

One last thought, the Norma brass (in the past) was a bit larger in dia. than Rem or Win 22/250 brass. It gave me bolt clicks on opening with loads that were no problem with the Rem and Win brass. Your chamber may be a bit larger and you may not have that problem. It is just a thought.

Bob

 

[wapiti25]

You may want to do a ladder test to get a better tune on your rifle. Testing with smaller powder charges can be useful such as .2 or .3 gr during the ladder test. Also try different primers. Ladder tests should be done at a range of 300 or more yds, longer is better as you are looking for small verticle changes.

 

[Kingfisher]

I'll have to admit that I have yet to run a ladder test on anything, so I'll have to do some forum searching on the most suggested method(s). I understand it from a general sense, but not having done it, especially on a rifle with this level of precision I want to make sure that I've got my eyes on the right things. I'm trying to squeeze the most out of the gun without getting bogged down in the minute details of the benchrest world. I'm hoping to find a happy medium. To that end, I've been thinking about the .2-.3 gr. increment testing, just wasn't sure if I'd be able to see the difference in group size or not. At 300 though that might be a workable deal.

Unfortunately as far as primers go, I'm pretty limited. Everywhere around here is out of stock and all I have left is CCI BR and Federal 210, and I don't exactly have a pile of either. The CCI's have done well for me so far, and I think as far as primer choices go they're at the top of the list for most folks so I've hesitated to try the Fed 210's yet. Needless to say, I've got some CCI BR's set for stock notifications from several mail order places.

 

[dansig]

I've been trying VihtaVuori N-140 in my 6XC with good results.

this is from my last trip to the range, wind was about 10-15mph and shifting rapidly between 8 o'clock to 4 o'clock, like every 2 seconds or faster...

Lapua Scenar 105L bullets, N-140 37,4gr jammed .0015
Bat B, Krieger 7.5 twist HV contour 28", Shehane Tracker, Jewel 2oz

 

[Kingfisher]

Dansig, I'd say the majority of my groups resemble the lower right target? Most average slightly larger than that, but not by much. They're very close. Unfortunately I rarely get the nice clean round holes like you have on your top two targets. Probably because of either the backer boards they use at the range, or because of the lightweight paper the targets are printed on. I need to find some BR targets on heavy paper. They used to sell them around here, but I haven't been able to find them recently. I'll see if I can't snap some photos of some of mine for discussion purposes.

Fortunately the last of my backorder from Brownell's arrived yesterday. 2 lbs of Reloder 25 (no, not for the 6XC lol) and a lb of R-17. H-4350 has done so well for me so far, I don't know how much I'll be able to improve on it. Accuracy is solid, and velocity is good with low SD & ES. Hard to argue much with that combo. However... it's still worth the effort to tinker a little just to see what it'll do.

 

[confuzed]

Glad to see you having some success with your 6xc i have shot out a 6xc myself it took 2500 rounds to do it! built 3 and still have two that i compete with, all three were built with the same reamer! I have tried rl17, 8208, varget,h4350,h4831sc ,I have had the best consistency with h4831sc berger 108 gr match target and 105 hybrids. The best groups @ 400yds were with the 108's with 40.6 grs of h4831 20 thou in the lands br-2 primers norma brass I do turn the necks and check for run out. It will do .25 moa. P. S. you can buy the 22-250 hornady special o.a.l. case, lube it with imperial wax run it in you 6xc die then onto a neck expander it will look like its ready for fire forming but will work just fine for o.a.l. gauge

 

[Kingfisher]

I actually fireformed some Norma 22-250 brass that I had, then bought a tap and drilled/tapped a couple of the old cases. Works like a charm. The first one came out a little of center but works, but I did it again just because I wanted it pretty. The second one looks just like a Hornady modified case. Just had to increase the bit size a little at a time until the hole was the right size for the tap. The first case I went straight to the big bit and it didn't center up properly.

With a light work week for spring break I anticipate having some time on Friday to do a little load testing. If I do, I'll load up some rounds to ladder test H-4350, and I'll also do some loads with RL-17. Unfortunately, and shockingly, I don't have any H-4831 on hand at the moment.