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Ran with BLC-2 up to 38gr with zero pressure signs under 115gr Nosler CC. Going to keep pushing up tomorrow after I de-prime these and see if the primer pockets are holding tight. Again, these shot better than they had any right to with there being .4 gr difference between loads. Really looking forward to working these for accuracy. The 130gr Power Point are next.
 

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I am having problems with my new 270 MSR short stroking.
As I approach 38 grs of TAC with a 105 gr CBB loaded to 2.24", it shoots but will not lock the bolt back. I think that is getting pretty close to a hot load based on subjective recoil feel and primer appearance.

I used a Superlative AGB with standard carbine buffer and spring. Removing the GB, there are no signs of leakage around the hole and feeling with a small allen wrench shows it to be well centered on the gas tube hole.

I cleaned the chamber in case it was "sticky" but that did not make any difference. There is no difficulty in extracting a loaded cartridge.

In case the Superlative gas block is restricted internally, I have a regular gas block on order but it may be next week before it gets here.

I am missing some wire drills, but it looks like the gas port in the barrel is 0.088" in diameter and may be slightly larger. What is the hole diameter as drilled?

I was going to use 8208 XBR but no one has it online at the moment. From my understanding TAC is basically the same heat range and I saw that Brazos Jack was using it successfully.

Gas port hole size and any comments would be appreciated...
 

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I am having problems with my new 270 MSR short stroking.
As I approach 38 grs of TAC with a 105 gr CBB loaded to 2.24", it shoots but will not lock the bolt back. I think that is getting pretty close to a hot load based on subjective recoil feel and primer appearance.

I used a Superlative AGB with standard carbine buffer and spring. Removing the GB, there are no signs of leakage around the hole and feeling with a small allen wrench shows it to be well centered on the gas tube hole.

I cleaned the chamber in case it was "sticky" but that did not make any difference. There is no difficulty in extracting a loaded cartridge.

In case the Superlative gas block is restricted internally, I have a regular gas block on order but it may be next week before it gets here.

I am missing some wire drills, but it looks like the gas port in the barrel is 0.088" in diameter and may be slightly larger. What is the hole diameter as drilled?

I was going to use 8208 XBR but no one has it online at the moment. From my understanding TAC is basically the same heat range and I saw that Brazos Jack was using it successfully.

Gas port hole size and any comments would be appreciated...
Try turning the gas down a little , maybe too much gas and bouncing is the problem

Sent from my moto g(7) play using Tapatalk
 

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If your load is too hot, the camber pressure could be high enough to hold the case wall against chamber tight enough to over-ride extraction forces. When the pressure reduces the case becomes free of the chamber but there isn't enough gas left to completely cycle and pick-up the next round. This has happened to me several times when I'm trying to push the envelope.
 
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If your load is too hot, the camber pressure could be high enough to hold the case wall against chamber tight enough to over-ride extraction forces. When the pressure reduces the case becomes free of the chamber but there isn't enough gas left to completely cycle and pick-up the next round. This has happened to me several times when I'm trying to push the envelope.
I started at 37.0 gr and it was barely moving the bolt-no ejection of the empty. As I came up, it finally got to ejecting around 37.6 grs or so as I recall. I moved up to 37.9 and 38.0 with no hold back and stopped at that point to take it apart and look for something obvious.
 

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It's probably the lightweight bullets. You may need to drill the port out to .093(3/32")
I thought about that but since Brazos Jack was shooting them successfully, I thought maybe something else was causing it. I will try the different block and see if that does anything first. Guess I better try to order some good drill bits and pray I don't snap one off! Drilling thru melonite treatment does not fill me with confidence LOL
 

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I have some butter in the fridge that could be slipped into a sock and it would knock out a mule. I also have some soft whip.... :D I guess I could drive to San Angelo tomorrow and buy a good carbide drill and give it a shot. The wise thing is to probably to buy some heavier bullets which is what you designed it for in the first place but I often have to be different!

These days, when it comes to powder, and just about anything else, you buy whatever is in stock.
 

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I tried a few different bullets in varying weights with a few different powders. Here is what I tried...

270MSR

90 Speer Gold Dot .253
2.200"
*10X-33.3 =3070
10X- 34.5 = 3250

110 Sierra Pro Hunter .318
2.265"
A2460- 34.9 = 2868

110 Hornady Bthp .360
2.200"
A2460- 34.9 = 2920
H4895- 35.7 = 2984

115 Speer Gold Dot .401
2.200"
10X- 32.2 =2873
Xterm- 34.5 =2913
H4895- 35.0 =2870

130 Berger Hvld .462 (#27501)
2.285"
34.4 -H4895 -2784fps
34.0 -A2460 -2767fps
 

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Got in a regular gas block today and took off the AGB. Looking at the AGB outside in good light, I saw what appeared to be a very faint powder trail inside the block. Rather than loctiting the AGB, I went ahead and swapped to the regular block and loaded about four cases with a couple tenths of a grain less powder. They locked back shooting single rounds.

They had been ejecting around 4 o'clock and with the regular block, they moved to about 5. At this moment, I think may have fixed it. I have company coming in so I need to put everything away until I can get back to playing with it again next week. My next step is to determine why running new brass thru the sizer pushes the shoulder back more than it does on fired brass. Right now, it appears I need to set the die to expand the neck only without touching the shoulder on all the new brass. Then on the brass that has been shot, I will need to turn the die in a bit more to get the shoulder where it needs to be after firing...

I appreciate the suggestions and I am not surprised that Harrison, as usual, is almost always right when he talks about gas leaks. I just hate to glue it down until I know I am not going to be taking it apart again as its no fun trying to move it--blue loctite, or not.
 

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I have used CCI 450's, Winchester Match, CCI BR4's and Federal 205's. My setup prefers the BR4's. Your results may vary.

I shoot 130gr Winchester SP the most, but during testing I tried 110 Hor, 130 Berger, 145 Hor. and 120gr SST. I was consistently able to get better groups with BR4's.
 

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Just thought I’d give a rundown of what I do with my .270 AR and my .270 MSR. All my lowers are set up with H3 buffers and Tubbs flat wire buffer springs. All my DI uppers are set up with SLR Sentry 7 adjustable gas blocks. All uppers and lowers (6.8 spc, 7.62x39, .270 AR, .270 MSR, .358 YETI) all run mix and match just fine. This has resulted in most of these gas blocks being set from 7 to 9 clicks out. So obviously I could do the same with all H2 or H1 buffers or maybe even carbine buffers with the gas blocks adjusted fewer clicks out.

For the .270 AR (18” bbl) and .270 MSR (20” bbl) I use all small primer brass and CCI450 primers. For bullets 100gr and heavier, I use TAC. It seems to be a hair slower than 8208. My 8208 max loads ran ½ grain less powder and around 100 fps slower than my TAC loads. I like the Cavity Back 105gr for deer. I have to run one grain less of TAC in the .270 MSR but with its two inch longer barrel both chronograph right around 3050 fps.

This is just the way I do it. I think these cartridges are both easy and flexible to load for. So there is no right or wrong way.
 
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