275 TSX and bullet creep

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Re: 275 TSX and bullet creep

Postby Hoot » Sun Aug 02, 2020 9:37 pm

Just out of curiosity, you might want to mic (not caliper) a couple of the bullets from the box that are creeping on you to make sure you didn't get some factory fluke. No surprise on the smooth sided 250 FTX since there's nothing to hold onto but certainly not my experience when taper crimping down into a groove like you did, mic'd as close to the mouth as possible at .474. What kind of brass are you using and if not new, how many times fired? I use Hornady brass but I have also used new Starline brass in the past. The Hornady seems to be a little thicker walled but the Starline seems to make up for that with being a little harder.

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Re: 275 TSX and bullet creep

Postby msd4141 » Mon Aug 03, 2020 7:52 am

Hoot,
I am using once fired Hornady brass. I did not bell the case. I have a caliper, and a micrometer. I checked the crimp with both. .471 to .472 as close to the case mouth as I could get. I am wondering, since I had no powder or primer in the bullets, just dummy rounds, do you think the added weight of those two components would help slow the force of the bolt? I am using JP Enterprise silent captured spring for the bolt carrier. I am going to look to see if I can buy a lower pressure spring. I am running an adjustable gas block, so I might be able to make that work. A lower pressure spring would lessen the driving force of the bolt. The other thing I'm going to do is use a q tip like you were saying to remove any oils in the case and on the bullets, if there was any there. thanks for the response. Marc
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Re: 275 TSX and bullet creep

Postby Hoot » Mon Aug 03, 2020 11:50 am

msd4141 wrote:Hoot,
I am using once fired Hornady brass. I did not bell the case. I have a caliper, and a micrometer. I checked the crimp with both. .471 to .472 as close to the case mouth as I could get. I am wondering, since I had no powder or primer in the bullets, just dummy rounds, do you think the added weight of those two components would help slow the force of the bolt? I am using JP Enterprise silent captured spring for the bolt carrier. I am going to look to see if I can buy a lower pressure spring. I am running an adjustable gas block, so I might be able to make that work. A lower pressure spring would lessen the driving force of the bolt. The other thing I'm going to do is use a q tip like you were saying to remove any oils in the case and on the bullets, if there was any there. thanks for the response. Marc


I seriously doubt that the added weight of the powder and primer would factor in but you bring up an interesting point about the spring. I've always used a standard rifle spring (A2 Stock) and a [color=blue]weighted[/blue] bolt carrier to slow things down since I'm not running full auto. You can barely see or hear the difference with the naked eye, but it helped keep the brass from getting as scratched, scraped and generally beat up. I played with an adjustable gas block but never saw much benefit from it so it went on my 6.5 Grendel which did. The 450b is the only caliber I spend a lot of time on, that has such a struggle with neck tension. True, the .451 projectiles have a little steeper hill to climb than the .452. Without a doubt, Neck Tension is the "800-pound gorilla in the room" with regard to reloading challenges in this caliber. I'm still waiting for some member, looking to build on their gravitas here, doing an A/B Range Day thread between cartridges with sealant (like NATO uses) around the bullets versus none, all else being equal. Both slam chambering immunity, average velocity for a given charge and group size might be interesting.

WRT stab crimping, let me give you a word of caution if you ever go there. I once tried dual stab crimps, IE one in each of the driving band grooves of the 200 XPB. It definitely immobiled the bullet to a fault! I did not adjust my recipe downward in anticipation of higher pressure and it only took two shots with the lowest charge weight in the ladder, to convince me to abort the experiment. It felt like a (barely) controlled explosion the first shot and this is where "gene pool cleansing" lurks. Like a fool I figured it was a bad reload and shot again. Same result! RED LIGHT! I spent that evening pulling down a lot of loads I had prepared for the test. Luckily, monolithic copper bullets don't deform like jacketed lead ones do, once they've been loaded, so I was able to reuse the bullets, which constituted a significant chunk of change. When I pull down a load, if I can see any deformity in the bullets, either from general neck tension or a ring from the taper crimp, they go in the recycle box. Life's too short for wasting my time using deformed bullets, as I've found that the consistency of performance goes out the window. I actually have a BR caliber wood stock with about a pound of them stuffed in the butt for additional weight. A better value than buying a lead stock weight or sacrificing shot shells. Yeah ole Hoot's weird that way. ;)

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Re: 275 TSX and bullet creep

Postby msd4141 » Mon Aug 03, 2020 5:53 pm

Hoot,
Thanks for the insight. I do not plan to stab crimp the round. I am researching another alternative. JP Enterprise has the silent capture spring for the AR platform, and I use them in every upper I have assembled. I am thinking about trying the model with tungsten weights on it. I'm thinking, in theory, that the extra weight will slow down the speed of the bolt closure, and result in less creep. I also have an original cheese grater spring and buffer, and I am going to put that in and see if it's spring is weaker, or has any effect on it.
On a separate note, I have followed your writings on the 200g barnes with lil gun, and I get decent accuracy with 39g being the most consistent. The groups were not as good as yours, with mine being almost 2 inches at 100 yards. (still in the deer zone) I'm going to start testing some more with that bullet when we get back from vacation in 2 weeks. Thanks for all the help so far, Marc
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Re: 275 TSX and bullet creep

Postby PHR87 » Mon Aug 03, 2020 9:26 pm

Hi, I did some partial testing a few weeks ago and need to finish it out. But, the results of my testing were that it didn't significantly matter if the bullets were slammed forward.

I loaded 8 total with 39.5 grains of lil gun and loaded to a COAL of 2.335". Once-fired hornady black brass. Taper crimped to .472". I loaded all individually and rode the bolt forward on 4, then let the bolt slam forward for 4.

Results:
Riding the bolt forward: 1.33 MOA, Best 3: .35 MOA
Slamming bolt forward: 1.56 MOA, Best 3: .90 MOA

I also set up the stab crimp, but didn't shoot over a chrono. My accuracy results were in the same realm- 1.24 MOA to 1.5 MOA with 37/37.5gr of lil gun respectively. It felt stouter, but pressure signs were still ok. I want to load up some more and chrono them, as well as keep a closer eye on the pressure. The public range that I went to wouldn't let me collect brass as it was fired and I wasn't able to tell which brass was which in real time. Need to get a brass catcher if I'm going to keep going there...
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Re: 275 TSX and bullet creep

Postby msd4141 » Tue Aug 04, 2020 3:39 am

Thanks for the reply PHR87,
Your post is helpful to say the least. Since this is a deer gun, I typically only need 1 shot, (not always though Ha Ha) so I could just ride the bolt home. There are occasions where 2 is needed , or what if 2 bucks came out? I tried the old style cheese grater buffer and spring, same result, bullet creep was about .016, from 2.33 to 2.49 so that didn't have any positive effect. I tested a brand new starline brass, full length sized, no bell, and loaded a dummy round to 2.33 which had less creep, but was still evident.
I am thinking that the creep is not a huge factor, especially when factory rounds do the same thing, BUT these 275 g TSX are loaded longer to start, and that is where I get concerned due to it being closer to the lands to begin with. Has anyone loaded the 275 TSX to the 2.25 specs that Hodgen, and Barnes called for? I know there would not be any cannelure to crimp into with the TSX, but the FTX has none, and it creeps, and everything works. Thanks for all the responses guys.
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Re: 275 TSX and bullet creep

Postby Moore77 » Sat Aug 22, 2020 11:10 am

Al in Mi , a friend is using the Lee set and is seeing very good results with the crimp die . Just information.
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Re: 275 TSX and bullet creep

Postby PHR87 » Tue Sep 01, 2020 7:59 am

A quick update from the range last week-

My best overall group was again the 40gr Lil gun at 2.335” with a taper crimp. I got a 1.05 MOA 4 shot group with that. 2344 FPS average with a 26 FPS SD. Pretty solid elk medicine!

I also got a 1.04 MOA 3 shot group with 39.5 gr LG and a stab/taper crimp.

I’ve decided that I have a lot of data on the taper only 40gr load and I’m loading that for hunting this year. I may continue to play around with the stab crimp for the future, but it seems that it doesn’t help that much and is an extra step. I’ll do one more test of mag-loaded/bolt slammed ammo, but I’m pretty confident that it won’t matter much. I’ll continue to update with that data as I get it.

Thanks for the help and I hope I can post up a picture of an elk that was landed with the 450 BM!
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Re: 275 TSX and bullet creep

Postby msd4141 » Wed Sep 09, 2020 7:20 pm

I finally ordered a Hornady OAL gauge and measured my tromix 1:24 18" barrel. I come up with 2.410 total to where the bullet touches the lands. I loaded some 275 TSX with H110 and REM 7 1/2 to a COAL of 2.320 and crimped into the cannelure to .472 with charges starting at 36gr and up to 39gr in half grain increments. I tested on targets at 100 yards. I rode the bolt home on each shot loaded 1 at a time. The best group was 39 gr with ALL 3 HOLES under an inch and traveling at 2125fps average :o I was happy with that, but I want to have more than 1 shot, and follow up shots would put the bullet close to the lands when the bolt went into battery with the bullet creep. This is too close for my comfort.
I decided to try the Hodgen recipe with the 275gr loaded with H110 at 2.250 COAL. The best group I had from 34gr up to 37gr in half grain increments ended up being 36.5 gr at 2050 fps average and all 3 holes touching. Again that was 100 yards. I crimped these 2.250 COAL rounds with the Hornady taper crimp to what I can best tell .476 as the cannelure was buried in the brass on the shorter rounds and I could not crimp into them. I tested these with extra rounds in the magazine. I extracted the second round after it self loaded, and the bullet creep went from 2.250 to 2.256 I tested 1 more the same way, and after extracting the case, I measured the bullet creep on that from 2.251 to 2.257 I find this to be an acceptable creep as even the factory loads creep about the same. I would load some pics, but it does not seem to be easy. I have ok results on some of the other charges as 1 1/2 inch groups were the max spread and who knows, I may have pulled on some of them. Here in Michigan today it was 66F and cloudy and humid with no wind.
What is the consensus on the speed for the 275 TSX at 2050fps at the barrel with a magneto speed? Most of my shots will be 125 yards or less, and I'm sure from what I read, these bullets will open at 1200 fps or more. I appreciate every ones help with this endeavor of mine. Needless to say, My shoulder is a bit sore right now :lol:
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Re: 275 TSX and bullet creep

Postby Al in Mi » Thu Sep 10, 2020 4:29 am

I'd say your good to go with that 275gr Barnes.

?? Did you ever take that 2nd round and rechamber a couple more times it to see if it moves anymore?
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