Jgun

I think the eye relief issue kind of comes with the territory if your mounting a separate low power and not always high quality magnifier, behind your unmagnified red dot. I know the XPS I have is NV compatible but since I don't have any I can't offer anything on that. In the two setups I'm presently running, the XPS with 5X flip to side behind, and the Trijicon TR -24 with small compact red dot mounted at 45 degrees, I find that I am faster with the second setup because I just roll the gun slightly and I can use either optic, since the red dot is not eye relief sensitive I just set up so I have the proper cheek weld for the long range optic and I'm in the right place for the red dot as well. An added benefit is that the two optics can be zeroed for different ranges . What I find with the Eotech set up is that although I like the big window, I find myself moving my head back and forth when I flip the magnifier up and down. Besides which, I have to move my front hand position to lock it in place and then again to release it. I'm just guessing here but I think that unless you had a magnifier with a big eyepiece, when you flip it down in front of the eotech, your going to look through that square window and see a smaller round lens surrounded by the black housing, effectively reducing your field of view, besides which, I doubt your going to be able to find a magnifier that has enough eye relief to allow you to fit the eotech between the back of the magnifier and your eye unless you have your face right up against the eotach.I'm curious, You say your waiting for more input, If you already have the eotech and magnifier why don't you just switch them?

the term timing the comp, refers to lining it up in such a way that the holes/ports are oriented so that they will be most effective in counteracting the forces placed on the gun by the projectile while it travels down the barrel, that and the recoil from the charge, since the line of the bore is above where you hold your gun, it wants to rise, that is why they put holes on the top on some MB's to counteract that. also the bullet traveling down the rifling in the barrel wants to twist the gun in the opposite direction, so you will see on some that there will be holes that are located asymmetrically to (hopefully) counteract that. Based on the fact that there are so many designs out there that are so totally different from each other, I think that to a great extent compensator/muzzlebrake design seems to be as much art as science. kind of like surf board design.

I think this was already stated somewhere else on the forum, but looking at the two different sights mentioned, I would be inclined to say that the KAC are definitely nicer. It's too bad they designed the rear as a peep sight. I generally use iron sights for rapid aquisition closer targets and the main optic for longer range. I think that the other,fixed sights would be better for that (for me) too bad they stick out so much and aren't folding.

I have an Eotech XPS on one of my guns, with a fixed 5X magnifier (without reticle) mounted on a flip to side behind it. I really like the setup, although I prefer the red dot at 45 degree and the main optic in the normal location. I don't see why it couldn't work for you, and a side benefit would be that the reticle of the Eotech wouldn't get bigger when you flipped the magnifier down in front, kind of like a FFP scope. when you test it your going to have to let us all know how well it works for you.

I saw a post on this, and thought I'd pass it along. I spoke to the people over at Leupold, and as many of you probably already know, through their custom shop you can get BDC reticles made for specific loadings of certain cartridges. I asked them about the 300 BLK and they said they should be able to do it as long as you can give them the pertanent data for your load. I think they told me the charge for the custom reticle was + $40 over the price of the scope, Now they don't offer it for every scope they make (no illuminated reticle scopes) but I think it might be useful for me, so as soon as I have settled on a load for my 300, I'm going to try one of their custom BDC reticles out.

Survivalshop, I would agree with you, that what I am trying to do here is at the high end of what this cartridge is capable of, kind of like what we do when we shoot 9mm Major in IPSC pistol. I noticed that the load listed by RSilvers (who I would consider the authority on the cartridge) for making major is 20gr of A 1680 behind a 175 SMK bullet loaded in "new production Remington 300 BLK brass) As soon as I get the Rem brass and some of the Alliant powder, I plan to try that load as well as picking up where I left off with my load development, but this time using the Rem brass.

Matt, You are, of course correct. I need to go to the trouble to verify things that I post instead of just going by memory. It's good that you called me on this because when I am timing one of these things or a barrel nut for a rail, I always go to the trouble to double check the math. As you might be able to tell from the opening of my reply, I was going by my recollection and didn't bother to double check before posting. I'm glad that it apparently didn't cause 6132 expert to take off too much material, in fact since my math was off in the other direction, he would have been taking too little off even if he had followed my advice, But in the future I intend to try harder to proof my posts/replies so as to not cause someone to screw something up because they followed my advice.

I've had one low pro GB that gave me a lot of trouble. It was an adjustable one. The Noveske and Vltor GB's that Ive used have never given me any problems. I don't know what brand GB your using, but keep in mind, there is no gas passing through that roll pin hole so if needed you can slightly open up the hole in the gas tube, just enough to allow the pin to make it though the GB and GT. Sometimes the pin hole in the GB is not drilled exactly in the center of bore that takes the GT so if it looks like the cross drilled hole is low you can round the hole in the GT slightly on the bottom. Theres really not very much meat there so we're only talking about a couple of thousandths but if the roll pin hole in the gb is obviously mislocated by a lot, then you should send it back for a replacement.

If I recall correctly, the 5/8"-24 thd on most 300 BLK barrels, works out to around .015" linear movement for 360 degrees rotation (one revolution) so 1/4 turn would be about .0035" linear movement. Personally, I don't really like crush washers preferring the shims or facing off material from the MB, but if you feel that your already torquing the MB as tight as you want to go, you can always, get a piece of emery paper, and using a flat surface, just make figure 8's with the crush washer (or the back of the MB) until you remove .002" or so.

Speaking to my friend (who got me involved with the 300BLK in the first place) about the case splitting. He pointed out that when I cut down the brand new LC brass, I'm removing the annealed neck from the brass. He also suggested that I consider neck turning the brass because the case thickness of the newly formed neck on my 300 brass is thicker than the thickness at the neck of unmodified Lake City 5.56 brass. I haven't had any problems so far with my loads using 145gr BT bullets, but, if I have to go through this much work to get usable 300 brass for my intended purpose, I'm thinking that factory brass will be a more desirable solution. I've also been told that there are companies that will perform annealing services on your brass. If I can't locate new factory brass, I may send some of my newly formed brass off to be annealed, before I make up any more test loads.

He's selling 300 brass formed from once fired Lake City .223 brass. I'm forming mine from new unfired Lake City brass. Unless he's doing an annealing process, it's not really much different than what I've already got. I'm hoping to locate some factory formed brass like Survivalshop bought, but I'm going to give him a call and ask if in fact he does anneal the necks. Thanks.

Have you tried installing the roll pin from the other side of the GB? Also, sometimes on especially tough ones I'll bevel the end of the pin slightly to help get it started into the second side of the GB after it passes though the first side and the gas tube. Also make sure that the bottom side of the gb (where the roll pin hole is) is fully supported.

Anyone seen factory brass in stock any place?

Although I don't have any of these loaded rds left, The bullets are, from L to R 155gr Lapua sceiner, 175gr SMK, and 180gr ballistic tip. the bottom of the tape on each shows where the front edge of the case was and how deeply I had to seat them in order to fit the magazine or chamber. I was thinking that if the problem was somehow related to the forming of the brass, If I could find some new production 300DLK brass, and if I duplicate the same loads I'll know that it's a problem with the brass if the if the problem doesn't reoccur. I had no brass splitting problems with the 145gr's I loaded, even though those bullets had the shortest seating depth of any of the test loads.

I will post some pics ASAP, but in the mean time. The brass was all brand new Lake City brass I bought from Midway, cut down in a lathe and formed using the Forster dies. My first test loads were 145's and they all performed well with no pressure signs. This time I loaded bullets of 145, 155, 175, and 180gr, using different charges of the same LIL GUN powder for all loads. What I found was that the 145's this time are still not making power factor even though I bumped the load up 1 gr from the last time. I also move the bullet forward about .020" because I found using the COL gauge that I had lots of freebore in front of that loaded rd. I would have moved it forward more but didn't think there was enough case purchase on the bullet to do that. The 145's gave no problems, no pressure signs, and no split cases, but also failed to make the MV I need. I will increase the load and try them again in the future. The other 3 bullets were all limited in COAL by either the mag room or the lead of the chamber. In all of them I was seating the bullet deeper into the case than with the 145's. I'm wondering if this reduced case capacity caused a pressure problem, but none of the primers indicate that. I adjusted all 3 of them to be as long as possible but left the freebore at .030". Now all three bullet weights had some case splits, but when chrono'd there was no connection between the fastest loads and case splitting, the rds that were the fastest, and actually made PF didn't split their cases. I also noticed that there seemed to be a pretty wide range between the fastest and slowest rds in each ten rd batch I loaded to a particular charge, as much as 65 fps. Unfortunately I shot all that I loaded so I don't have loaded rds to post, but I will take pics of the bullet types I used and mark how deeply they were loaded into the case so you can see what I'm talking about. I think the 180gr bullet is loaded .150" deeper into the case than the 145. Of course the powder charge was also reduced so there were no compressed loads.

Not sure how I managed to post the pics twice? oh well.

Got the POF lower, so this is what the set looks like. Still don't know what I'm going to do with it.

I got out to chrono some test loads today, so now I need basic loading advice. I am probably being to cautious here, but I've never blown up a gun and don't think I want to find out first hand what it feels like. I tested bullets ranging from 145 gr to 180 gr, with various powder charges. I had 2 test rds that made my desired power factor, one was a 155gr bullet with16.5 grs of powder that gave me a best MV of 2073 FPS and the other was a 175gr SMK with a charge of 14.5 gr of powder that gave me a best MV of 1894 fps. Now both of these loads did not give the stated fps as an average. the other rds of each loading that I tested all were slower, so If I hope to use either of these rds I will still need to increase the powder charge a little. None of the rds I tested today showed any over pressure signs on the back of the case, no blown out primers, no trouble extracting, BUT, I had several cases that split on me today. All the cases split at the front where the LC brass was resized to accommodate the .30 cal bullet. My question's are, Is the splitting likely a result of too much pressure? Could it be because the brass needs to be annealed? I have adjusted the COL on all of these rds to get the bullet ogive withing about .030" of the lead to the rifling, could that be a problem. I'd like to work up some more test loads, but I need to figure out why the cases are splitting before I'll feel comfortable increasing the charge on those loads that look promising. Any advice is appreciated.

I'm also wondering what operation the 3 die Redding set does that the Forster doesn't. So far I've been able to form and load functional rd's with my set, and when I compare my once fired brass to new brass that I form, the shoulders are almost exactly in the same place. Maybe the separate FL sizing and neck sizing dies allow you to fine tune the neck to certain bullets? As you say, it might be good for ultimate accuracy with the bolt guns, and I also like the Redding dies, but at twice the price, I'm wondering if I'm going to see any measurable improvement in the quality or accuracy of my rds if I go to the added expense, and extra work, to do an additional operation in my single stage?

Robocop, Do you have an ETA for your barrel? I'm assuming that you gave them a bolt to headspace the chamber and I see that one of the other members said that he has already received a Young Mfg. carrier, so I'm guessing that if the barrel shows, and you still can't get the SI BC you should be able too just order a Young's. Just wondering, aside from that, are you ready to put it all together?

Most of the different parts/components out there for the AR, came about due to a particular need, either perceived or real. So as is always the case, you need to match your components to that need, and to work well with each other. The super light CF competition FF tubes usually serve one purpose, to give you a place to hold the gun without burning your hand (and to protect the gas tube so I guess that's two) If you have a need for more than that, like mounting a bipod or BUIS, than you start to need rails, and the weight starts to go up. If you know that you'll never change your accessories than you can just mount rails where needed and save some weight, most of us don't know for sure about that so a fully railed handguard allows us to try different setups to see what works best. Same for barrel length, if your building a long range gun your going to need the longer barrel, and consequently, you are going to be building a heavier gun, no way around it. Same for the optic, as you stated, doesn't make sense to put 1000m optic on a CQB carbine build. As you also stated, the stock can add or save 1.5 lbs on your build, with the ACE fixed being the lightest I know of, but sometimes the extra weight of a heavier stock improves the balance of the gun in such a way that the extra 1lb added to the total weight is worth it. Same with rail length, most agree that you want the handguard to cover the gas tube, but different gas systems IE carbine,mid,rifle are all going to give different gun performance , and will also limit what the shortest handguard you will likely go with. I think it's all about taking weight where you can while not compromising your planned purpose for the rifle.

Since the original poster no longer has his IR receiver, we'll never know how his upper's dimensions compared to yours, but for academic purposes, I'd say that it sounds as though, assuming that you were to use the same barrel, your IR upper should locate the BCG .036" further forward from the front shoulder of the IR upper compared to the DPMS upper, Now, maybe I misunderstand some of your measurements but, as I understand it your saying that the two uppers are the same OAL front to back right? The key thing you have to determine unless you've already done it and I didn't get your measurements correctly, is that you have to make sure that the front pivot pin bore (which actually locates the upper on the lower in relation to the buffer) on both uppers is located in the same place in relation to the front and/or back face of the upper receiver. If that is the same on both, I would think that your IR receiver set should not have the problem that the first poster's had..

I was planning to wait until my POF lower arrived (en route, will be here beginning of the week), but when I came in today and this was waiting, I couldn't help myself, so I decided to post a couple of admittedly bad pics of the new POF compatible upper to see what you guys think. I don't have many .308 parts on hand right now so I couldn't check barrel extension fit, but the barrel nut, BCG and charging handle all seem to fit OK. The rail height looks good also. It fits on my Kaiser lower and the fit at the back is excellent although I couldn't pin it because of the pin OD difference. At this point I still don't know how the fit will be on the POF lower, and I'm also not sure how the finish will match between the upper and lower, but if I'm not satisfied with it, I will make this my first desert tan or FDE build.

H2O man, I also like those Sage stocks. I see your posts on the Rouge, and impressive as it is, I "think" that I prefer a rifle with the magwell in front of the trigger due to the fact that I can make faster mag changes. For my first M1A I've decided to go with something built with accuracy as the primary goal. As Majorjim states above (and you of course already know) their getting sub MOA out of them these days, in fact the first one I ever shot was sub MOA for me. To that end, I have placed an order for a JAE Gen3 stock, and plan to go with a 22" barrel. For the next one, I thought I'd go with an 18" in a Sage or possibly the McCann. I thought it might be fun to see just how light I could build one of these. Do you have any personal experience with the McCann stock?

Doesn't Midwest Industries offer a 2 piece drop in railed hand guard that utilizes the plastic handguard monts and doesn't effect the delta ring?