Put Together my First Custom Rifle

[264MHC]

Hello All,
I've been a long time reader of this forum and have found it to be a great source of interesting and valuable information, so I finally joined. This will be my first post so I apologize for the length. I just finished putting together my first custom bolt rifle and enjoyed the entire process. Because I work overseas and don't get home more than a week every couple of months, the project took about a year and 3 months from start to finish. I would like to explain the whole process and the different issues I ran into along the way as well as discuss all of the components of the build to hopefully help others looking to start a similar project.

The Rifle

When I started this project, I was originally going to just rebarrel my Savage 114 that has an aftermarket 6.5x55 1:9 Twist barrel. While this rifle shoots great, the 9 twist (ordered an 8, got a 9, long story) limited my bullet selection, and the heavily tapered swede case required trimming after every firing. I designed an improved version of the 6.5x55 called the .264 MHC (more on this later) and had Manson build a reamer. I sent the reamer to Northland Shooters Supply and had them spin up a Savage pre-fit 6.5 1:7.5 Twist Heavy Sporter barrel. I then started a new job and had a lot more disposable income so I started thinking I might want a whole new gun instead. One night I started researching custom actions with Savage small shank threads and the whole thing started from there.

While researching I found it very helpful to see both price and weight of individual components, so that is what I will list here:

Shilen DGR Left Hand Long Action - 30oz - $950
Shilen 20 MOA Pinned Rail - 2.1oz - $60
Criterion Heavy Sporter 6.5 1:7.5 25"- 52oz - $380 ($50 Upcharge for custom chamber)
Bighorn 12 Point Barrel Nut - 1.5oz - $40
Mesa Altitude Stock LA 3B Inlet - 26oz Bedded and Finished - $575
Grovtec QD Cups - Included in Stock weight - $6
Spartan Gunsmith Adapter - Included in Stock Weight - $34
Triggertech Special Trigger LH - 2.5oz - $200
HS Precision LA Standard DBM - 9.7oz - $315
Wyatts T27 Torx Stainless Action Screws - .7oz - $7
Zeiss V4 4-16x44 ZMoa2 - 21.4oz - $820
Seekins 30mm .82 Low Rings - 4.1oz - $100
Flatline Ops Sniper Articulating Level - 2oz - $140

Total Weight - 9Lbs 8oz

So here are some issues I had to deal with. Putting these rifles together is certainly more involved then bolting together an AR. So I originally planned to use Hawkins Hybrid Low rings that are 3.7oz, and would have saved 4.5 oz over current rings/rail/level set up. Unfortunately my scope would not work with these rings. The magnification dial is too large to fit above the base section of the rings, forcing the whole scope back, which in turn had the front edge of the front ring about .2" farther forward of the mounting length and into the taper up to the objective. It was either higher rings or the rail set up and I didn't want the higher rings. I'm kinda glad it happened because the Flatline flip out level is much more functional, and its much easier to remove and re-attach the scope if necessary. Next thing is I started out with a Hawkins BDL on this rifle. I have never had a BDL rifle and decided I just did not like how that setup functioned. The HS DBM fit the bill perfectly and I absolutely love everything about it aside from the weight (BDL with box, spring and follower weighed 5.2 oz). If they came out with an Aluminum version, it would be perfect. One hiccup I had with it was that the front of the housing on the Triggertech contacted the front of the cutout on the bottom metal. A little Dremel work fixed that without issue and out of sight.

And on to where most of the problems arised: The Stock. I will start by saying that I love the stock. The fit and finish is superb and it fits me quite well. I love the thick vertical grip and the textured gripping surfaces. The light weight is the obvious perk. Anyway, the bottom metal inlet was too thin and required about 1/16" of material be removed for the bottom metal to fit. Once I fit the bottom metal I found out that the mag was sitting too low, allowing the bolt to slide over a round in the mag. After grinding and checking the front and rear pillar areas multiple times, I finally got the bottom metal sitting high enough to properly feed. The bottom metal is now perfectly flush with the bottom of the stock so better than it was anyway. The barrel channel fit really well except around the shank area, which was expected with the barrel nut. I certainly do not hold these issues against Mesa/AG, as I know there are so many parts with so many tolerances out there, but it was more work than I thought I would have to do.

My next issue has more to do with my skill level and tool choice than the parts. I installed the flush cups in place of the swivel studs in the butt and farthest forward stud locations, and the Spartan tripod adapter in the rear fore end stud location. I used a 1/2 Forstner Bit for the Flush cups and a 3/4 for the Spartan, to start and finish the holes, and a regular 1/2 and 3/4 bit for drilling through the embedded 1/4" aluminum bar in all three locations. I wish I could have found slightly smaller bits locally because the holes ended up slightly oversized as shown above. Also I should have waited to use my buddy's drill press, but I was eager to get this thing together so I used my regular 20V Dewalt. Turned out fine but not gunsmith quality.

This Post is getting long so I will continue in a new one.

 

[elkaholic]

Welcome to the forum! Thats a great job for a first post. Very nice build. Congrats!

 

[manitou]

Uhhh, I don't know how to tell you this... but the bolt is on the wrong side.

Anxious to hear how it shoots.

 

[264MHC]

The Cartridge
The 264 MHC Cartridge is my version of an improved 6.5x55. I chose to improve the 6.5x55 case because I already had experience with the parent and I feel that the case capacity of the improved version is about the ideal compromise of barrel life and performance in the 6.5 bore. This cartridge has about 5 grains more powder (not water) capacity than the standard Swede, slightly more than 260AI and slightly less than 6.5-284 and PRC. In addition, Lapua 6.5x55 is some of their cheapest, regularly found around $80 per 100. Why did I not go with one of the available designs? Well there are no barrel manufacturers with a reamer for any of them and dies are basically non existent anyway so my cost to chamber and reload for this cartridge was no more than any of the other designs. Getting a custom reamer through Manson is only slightly more expensive than buying one of their standard reamers. Manson does have the original BJAI reamer but it has a .100 Freebore which is too short for my purposes.

The .264 MHC has a 35 degree shoulder and .0098 Taper. There were 3 reasons I chose 35 degrees for the shoulder. First is I can use a 270 wsm die to slightly bump the shoulder until my custom Whidden die is in hand. I haven't had to bump the shoulder after 3 firings on a few pieces of brass so this may be a moot point, but I didn't know that would be the case when I designed it. Second, while I'm sure someone has done it before, there are no well known designs with a 35 degree shoulder, and I like to be different. The BJAI and standard AI have 40 degree, and the GWI and PR&T have 30 degree. The 6.5 Addiction has a 37.5 Degree. I also felt that the 35 degree shoulder is the ideal compromise between case growth and feeding, and just looks balanced. I probably don't have enough experience with other shoulder angles to make this claim, but I'm happy with how it turned out.

The attached image is my drawing of the chamber design. This is not the exact reamer print but all the measurements are the same.

I designed the freebore at .200 to be optimal for the 156 Bergers in Lapua brass. Of course the 156 Bergers had not yet been released when I made my design, so I used 150 Sierras seated .050 above the neck-shoulder junction, just in case the 156 had a longer bearing surface. When I recieved my first two boxes of 156's, and tested CBTO, I found that the design is close to perfect, with the boat tail about .040 above the neck-shoulder junction seated to the lands (2.525 with Hornady Comparator). This freebore is a little long for 140 class bullets but I only plan to shoot 150's and 156's.

The only thing I would change about the design would be to shorten the overall chamber length. My Lapua brass measured and average of 2.155 case length, and after fire forming, shrunk to 2.135 and hasn't grown much so far. .035 short of the chamber length is not ideal, but will probably be just fine, and I will likely never have to trim this brass again. Also, the headspace is set to be tight on the virgin Lapua, so my fired brass from my other chamber will not chamber. I did not expect this and was slightly disappointed, but I don't plan on using brass fired in my other chamber anyway.

Performance
Because of my schedule, I have only been able to do some preliminary velocity ladders with several powders behind the 150 Sierras and 156 Bergers, as well as one seating test with the 156's. To set a baseline, I will share some of my data with the standard Swede from a 24" barrel. With 140 Hornady BTHP's and RL23, I maxed out at 46.8 grains for 2840 fps. With the 150 Sierras (Keyholed with the 9 twist), I maxed out at 46 grains for 2731 fps. Both with Fed 215 Primers in Norma Brass. Using this data I worked up a fireform load from 46-48 Grains of RL23 in virgin Lapua with Nosler 140 RDF's. 48 Grains shoots about .75 at 2840 in the new chamber, producing totally formed brass, not bad for a fireform load.

With the 150 Sierras in the MHC, I tested RL 23, Ramshot Magnum, and IMR 7977. For RL 23, I maxed out at 50.4 grains for 2916 fps, with a node around 50 Grains for 2898 fps. 49.6 was 2892. Case was full at 52 Grains.
Ramshot Magnum looks to be a good performer for this cartridge. I maxed out at 56 Grains for 2950 fps, with a node around 55 for 2902. Case was full at 56.
IMR 7977 Appears to be way too slow. The case was full at 53 grains but that only produced 2789 with no pressure. All of these loads were worked up from 4 grains below max.

For the 156 Bergers, I only tested VV N565. I was able to find some last minute so I reserved it for these bullets. This powder is a perfect match for this case. I started at 48 Grains which is listed as max for the standard swede in the Vihtavuori data, and worked up to 55 in .5 Grain increments. 55 is a full case. I saw the first ejector mark at 54.5 but had no flattened or cratered primers, and no hard bolt lift, even at 55. 54.5 was 2989, and 55 was 2993, so probably a node there. However, I chose to work around the 53-53.5 node which both produced the exact same 2870. In my first seating test, I used 53.4 Grains, as the temperature was 81 degrees when these velocities were tested. So far 2.52 CBTO or .005 off the lands is looking the best with a .93" 4 shot group at 200.

I've had some interesting observations in my testing so far. The way this case handles pressure is entirely different than the standard swede case. In the standard case, my first sign of pressure was almost always hard bolt lift. I almost never saw flattened primers or ejector swipes. With the MHC, I got ejector marks first but have yet to experience hard bolt lift. There could be several reasons for this. First I feel the low taper/sharp shoulder design is gripping the chamber walls much more effectively. Second, the MHC is in a custom action vs the Swede being in a looser factory action. And third, I am using Lapua brass for the MHC as opposed to the Norma I use for the Swede. I feel all of these factors are coming together to produce a quite significant performance increase over the parent case.

Overall I am extremely pleased with the performance and feel the extra effort was worthwhile. I am loving the new rifle and cartridge and can't wait to test it out on a nice whitetail. If anyone has any questions about the rifle or cartridge, feel free to ask.

Cole