LanceCriminal
3 January 2013, 08:43
Over a year ago, I made a post about a Mk12 Mod 0 I had built with a side-charging upper. When I first took it to the range, I was having issues with the bolt not going all the way home, and since the side-charger had no forward assist, I was stuck. Fast forward, and I replaced the upper with a standard BCM with F/A. I also finally decided to get a suppressor, so the side-charger also needed to go for that reason.
I *finally* got out to a good range, Best of the West in Tx. While it meant driving 25+ hours with a pregnant wife and 2 small dogs, it meant I had a chance to actually use the rifle as intended. Here are a few observations:
1) The bolt still was not chambering all the way. A little troubleshooting found that it only does this if I use the bolt release. If I rack the charging handle all the way back, it chambers properly. I started out with c-products 20-round mags, and to be all scientific, I tried with Magpul gen2 30 rounders, and a Lancer L5 mag. It didn't matter if the mags were full, half loaded, just 5 rounds, etc.
The Mk12 upper is currently on an LMT defender lower with SOPMOD stock, and a newly dropped in Geissele SSA-E. I used Federal XM193 and Black Hills Blue Box 223 77grn. Could having a carbine buffer/spring be causing the bolt not to seat all the way? I had no short strokes, or any failures of any sort aside from the first round chambering issue. This lower is also used with a BCM 16" m4 upper, so I would like to make sure that any adjustments made to work with the MK12 will still run the M4 properly. The MK12 bolt is a Young's M16 National Match chrome BCG and chrome bolt.
2) Spotters are important: The day I was at the range, weather began to significantly affect our ability to figure what was going on down range. The day started as 42 F, 3-4 mph cross wind, overcast and decent visibility. I was able to get my "qual", 3 hits on a steel plate @ 500yds within 5 rounds using 55gr Fed XM193. Even with the RSO and his 40+ magnification spotting scope, who turned out to be a great help that day, we could barely tell most of the time when I hit the plate. It was too quiet to hear, the plate didn't shift, and the splash was almost negligible. Due to a dark dirt berm, we also couldn't see puffs or impacts in the berm most of the time. A shift in visibility rolled in, and soon you could barely see the 1000yd and 750yd plates, and 500yds was getting iffy. I switched up to the 77gr, and the same issue of sometimes seeing hits, sometimes not still persisted. Folks with 308's had no such issues smacking the plates around and seeing their impacts, just me and my little mouse gun ;)
3) Eyepro: I learned some valuable lessons. First was that the eyepro I had really messed with my ability to get a cheekweld and would fog up from my breathing. Fortunately, the RSO allowed folks to pull up their eyepro if needed when on the scope, and agreed that if anything bad went down it was on them. I was fine with this, and this helped out on the fogging issue. Does anyone know of some eyepro that can help prevent fogging and still let you get a good cheekweld with proper eye relief?
4) Homework!: The RSO pointed out some homework I needed to do before I head out there again. I had not looked up my scope's subtentions for the mil-dot reticle (Bushnell 4200 Elite, 3-12 FFP Mil-Dot illum). The scope is mil dot, mil adjustment but I did not know the size of the mil dot, distance between centers, etc. I've found some documentation from Bushnell, but am still seeking more granularity on the issue. Next up was my ammo selection. I was using the Federal 193, blue box BH 77, and also brought Fed GMM 77grn. The thing I had not done was build any ballistics charts with the drops or wind adjustments. Since then, I went internet digging and have found a number of resources between web apps and Android apps I can use, with some decent baseline data for the factory ammo. Obviously if I really want to get out to 750yds (my goal) I will need a lot of practice, good data on my ammo, and a good spotter. I also need to work on my prone position with a bipod. I never have liked using benches or rests, mostly because I want to be able to shoot the same way whether there is a convenient rest or not. I had no experience previously using rifles with bipods, only the standard Marine Corps qual stuff with an A2. I'm now looking for tips in terms of shooting positions and stuff I can practice at home while dry-firing.
The biggest conclusion I made was that I really need to stop lollygagging and move back to Texas, because that was the most fun I've had in a long time and was the best range I'd ever used. I'd also love to find an entry level precision rifle class, however I currently have time and budgetary constraints due to an incoming baby mid-June. I came away satisfied with my rifle and equipment, not feeling like I need to go and spend piles more money fixing things that can be remediated with practice and training. I do feel like the rifle can shoot better than I can, and am eager to catch up and be able to shoot to its full potential. Oh, and the SSA-E trigger was sex.
I also came away seeing why the Mk12 evolved to the Mod 1. I built a Mod 0 based on how it looked, I will be honest that from the first time I saw it I liked it much better than the Mod 1 or similar spinoffs. Still, I can recognize why changes were made, such as the ARMS 40 rear sight preventing the scope from coming far enough back using the "spec" medium height ARMS rings, the SOPMOD stock making it so I basically was nose-to-charging handle, and the rifle being overall heavy. If I were to stick to the 18" barrel and rebuild it, Id just go with a 15" Geissele SMR rail, which would come nearly flush with the SPR/M4 can (when the stamp comes), get some Larue, Badger, or Bobro QD rings, and call it a day. Depending on price shenanigans I may get another lower just for it some day and transfer my A1 stock over to it. But in the mean time, I'm leaving it just the way it is.
Unless I find a cheap ARMS 40L rear sight....
I *finally* got out to a good range, Best of the West in Tx. While it meant driving 25+ hours with a pregnant wife and 2 small dogs, it meant I had a chance to actually use the rifle as intended. Here are a few observations:
1) The bolt still was not chambering all the way. A little troubleshooting found that it only does this if I use the bolt release. If I rack the charging handle all the way back, it chambers properly. I started out with c-products 20-round mags, and to be all scientific, I tried with Magpul gen2 30 rounders, and a Lancer L5 mag. It didn't matter if the mags were full, half loaded, just 5 rounds, etc.
The Mk12 upper is currently on an LMT defender lower with SOPMOD stock, and a newly dropped in Geissele SSA-E. I used Federal XM193 and Black Hills Blue Box 223 77grn. Could having a carbine buffer/spring be causing the bolt not to seat all the way? I had no short strokes, or any failures of any sort aside from the first round chambering issue. This lower is also used with a BCM 16" m4 upper, so I would like to make sure that any adjustments made to work with the MK12 will still run the M4 properly. The MK12 bolt is a Young's M16 National Match chrome BCG and chrome bolt.
2) Spotters are important: The day I was at the range, weather began to significantly affect our ability to figure what was going on down range. The day started as 42 F, 3-4 mph cross wind, overcast and decent visibility. I was able to get my "qual", 3 hits on a steel plate @ 500yds within 5 rounds using 55gr Fed XM193. Even with the RSO and his 40+ magnification spotting scope, who turned out to be a great help that day, we could barely tell most of the time when I hit the plate. It was too quiet to hear, the plate didn't shift, and the splash was almost negligible. Due to a dark dirt berm, we also couldn't see puffs or impacts in the berm most of the time. A shift in visibility rolled in, and soon you could barely see the 1000yd and 750yd plates, and 500yds was getting iffy. I switched up to the 77gr, and the same issue of sometimes seeing hits, sometimes not still persisted. Folks with 308's had no such issues smacking the plates around and seeing their impacts, just me and my little mouse gun ;)
3) Eyepro: I learned some valuable lessons. First was that the eyepro I had really messed with my ability to get a cheekweld and would fog up from my breathing. Fortunately, the RSO allowed folks to pull up their eyepro if needed when on the scope, and agreed that if anything bad went down it was on them. I was fine with this, and this helped out on the fogging issue. Does anyone know of some eyepro that can help prevent fogging and still let you get a good cheekweld with proper eye relief?
4) Homework!: The RSO pointed out some homework I needed to do before I head out there again. I had not looked up my scope's subtentions for the mil-dot reticle (Bushnell 4200 Elite, 3-12 FFP Mil-Dot illum). The scope is mil dot, mil adjustment but I did not know the size of the mil dot, distance between centers, etc. I've found some documentation from Bushnell, but am still seeking more granularity on the issue. Next up was my ammo selection. I was using the Federal 193, blue box BH 77, and also brought Fed GMM 77grn. The thing I had not done was build any ballistics charts with the drops or wind adjustments. Since then, I went internet digging and have found a number of resources between web apps and Android apps I can use, with some decent baseline data for the factory ammo. Obviously if I really want to get out to 750yds (my goal) I will need a lot of practice, good data on my ammo, and a good spotter. I also need to work on my prone position with a bipod. I never have liked using benches or rests, mostly because I want to be able to shoot the same way whether there is a convenient rest or not. I had no experience previously using rifles with bipods, only the standard Marine Corps qual stuff with an A2. I'm now looking for tips in terms of shooting positions and stuff I can practice at home while dry-firing.
The biggest conclusion I made was that I really need to stop lollygagging and move back to Texas, because that was the most fun I've had in a long time and was the best range I'd ever used. I'd also love to find an entry level precision rifle class, however I currently have time and budgetary constraints due to an incoming baby mid-June. I came away satisfied with my rifle and equipment, not feeling like I need to go and spend piles more money fixing things that can be remediated with practice and training. I do feel like the rifle can shoot better than I can, and am eager to catch up and be able to shoot to its full potential. Oh, and the SSA-E trigger was sex.
I also came away seeing why the Mk12 evolved to the Mod 1. I built a Mod 0 based on how it looked, I will be honest that from the first time I saw it I liked it much better than the Mod 1 or similar spinoffs. Still, I can recognize why changes were made, such as the ARMS 40 rear sight preventing the scope from coming far enough back using the "spec" medium height ARMS rings, the SOPMOD stock making it so I basically was nose-to-charging handle, and the rifle being overall heavy. If I were to stick to the 18" barrel and rebuild it, Id just go with a 15" Geissele SMR rail, which would come nearly flush with the SPR/M4 can (when the stamp comes), get some Larue, Badger, or Bobro QD rings, and call it a day. Depending on price shenanigans I may get another lower just for it some day and transfer my A1 stock over to it. But in the mean time, I'm leaving it just the way it is.
Unless I find a cheap ARMS 40L rear sight....